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1
Sadegzadeh, Massud. "Abrasion resistance of concrete." Thesis, Aston University, 1985. http://publications.aston.ac.uk/14253/.
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This thesis describes an experimental study of the abrasion resistance of concrete at both the macro and micro levels. This is preceded by a review related to friction and wear, methods of test for assessing abrasion resistance, and factors influencing the abrasion resistance of concrete. A versatile test apparatus was developed to assess the abrasion resistance of concrete. This could be operated in three modes and a standardised procedure was established for all tests. A laboratory programme was undertaken to investigate the influence, on abrasion resistance, of three major factors - finishing techniques, curing regimes and surface treatments. The results clearly show that abrasion resistance was significantly affected by these factors, and tentative mechanisms were postulated to explain these observations. To substantiate these mechanisms, the concrete specimens from the macro-study were subjected to micro-structural investigation, using such techniques as 'Mercury Intrusion Forosimetry, Microhardness, Scanning Electron Microscopy, Petrography and Differential Thermal Analysis. The results of this programme clearly demonstrated that the abrasion resistance of concrete is primarily dependent on the microstructure of the concrete nearest to the surface. The viability of indirectly assessing the abrasion resistance was investigated using three non-destructive techniques - Ultrasonic Pulse Velocity, Schmidt Rebound Hardness, and the Initial Surface Absorption Test. The Initial Surface Absorption was found to be most sensitive to factors which were shown to have influenced the abrasion resistance of concrete. An extensive field investigation was also undertaken. The results were used to compare site and laboratorypractices, and the performance in the accelerated abrasion test with the service wear. From this study, criteria were developed for assessing the quality of concrete floor slabs in terms of abrasion resistance.
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Vassou, Vassoulla. "Abrasion resistance of fibre reinforced concrete floors." Thesis, Aston University, 2003. http://publications.aston.ac.uk/14147/.
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This thesis focuses on the investigation of the abrasion resistance of fibre reinforced concrete floors at both the macro and micro levels. A literature review of the available literature concerning subjects allied to the current project is included. This highlights themes relevant to wear mechanisms and the factors influencing it: factors that affect the abrasion resistance of concrete and several test methods for assessing it; and the historical development of fibres and the properties of different fibre types and their influence on concrete. Three accelerated abrasion testers were compared and critically discussed for their suitability for assessing the abrasion resistance of concrete floors. Based on the experimental findings one accelerated abrasion apparatus was selected as more appropriate to be used for carrying out the main investigations. The laboratory programme that followed was undertaken to investigate the influence of various material and construction factors on abrasion resistance. These included mix variations (w/c ratio), fibre reinforcement, geometry, type and volume, curing method and superplasticizing agents. The results clearly show that these factors significantly affected abrasion resistance and several mechanisms were presumed to explain and better understand these observations. To verify and understand these mechanisms that are accountable for the breakdown of concrete slabs, the same concrete specimens that were used for the macro-study, were also subjected to microstructutural investigations using techniques such as Microhardness examination, Mercury intrusion porosimetry and Petrographic examination. It has been found that the abrasion resistance of concrete is primarily dependent on the microstructure and porosity of the concrete nearest to the surface. The feasibility of predicting the abrasion resistance of fibre reinforced concrete floors by indirect and non-destructive methods was investigated using five methods that have frequently been used for assessing the quality of concrete. They included the initial surface absorption test, the impact test, ball cratering, the scratch test and the base hardness test. The impact resistance (BRE screed tester) and scratch resistance (Base hardness tester) were found to be the most sensitive to factors affecting abrasion resistance and hence are considered to be the most appropriate testing techniques.
3
Halim, Mahdi Hassan. "Truck tyre tread rubber : compounding and abrasion resistance." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/6743.
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Alshabbani, Haydar Swiry Rahi. "Metal matrix composites with diamond for abrasion resistance." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22944/.
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Metal matrix composites (MMCs) have been used in many applications (such as automotive, aerospace and construction) for many decades. Recently, there have been interesting developments in this type of composite, applying them in electronic and thermal applications such as with semiconductors, in electronic packaging and heat sinks. This is particularly the case for composites of a metal matrix with diamond which are considered a modern sub-class of metal matrix composites. However, while the thermal properties are exceptional, this class of composites has not been extensively examined for mechanical and tribological behaviour, and it may be possible to apply these composites in practical applications, especially those that require extreme mechanical and tribological strength, for example cutting resistance for security applications. Therefore, this research looks for a composite material consisting of metal matrix and diamond particles, which resists abrasive cutting. This progresses through a series of steps, developing methods to process the material, understanding the mechanics of abrasive behaviour and optimizing the composite structure to resist abrasive cutting. Gas Infiltration (GI) casting under gas pressure has been applied to metal matrices with relatively low melting point (aluminium (Al) and tin (Sn)) to obtain a significant penetration of the metal into a preform of diamond particles. Different diamond particle sizes (63-75, 212-250, 420-500 μm) were used to strengthen the Al matrix and diamond coated with a thin Ti layer was used to attempt to enhance the bonding forces between the aluminium matrix and diamond. Al-1 wt. % Mg as a matrix alloy was utilised to investigate the possible effect of Mg on bonding phases and to reduce the surface tension of molten aluminium during the infiltration process. Epoxy was also used as a matrix with diamond in this research by gravity infiltration. Tribological and microstructural tests were performed on the samples, and the results show that the surface modification (Ti coating) of diamond particles has an important role for enhancing the bonding between the aluminium matrix and diamond reinforcement as is apparent under SEM observation, thus improving wear resistance. The coating layer works to either catalyse the graphitisation of diamond surfaces to then dissolve carbon in the metal, or reacts at the diamond surfaces to form carbide crystallites at the interface. This may be one of the reasons contributing to the bonding between the different matrices and diamond. The presence of some of these phases was indicated with XRD patterns and Raman spectra. The principal characterization method was by abrasion cutting tests, which have been carried out on all the samples made. One particle size range, 420-500 μm, of diamond coated by Ti, has been used to manufacture composites with different matrices (titanium (Ti), nickel )Ni(, copper)Cu(, tin)Sn) and epoxy) using different production methods (PM and SPS) for the transition metal matrices due to their high melting points. The abrasion cutting tests of these composites showed that the bonding between the metal matrix and diamond reinforcement and the processing temperature, have an important role in enhancing the abrasion wear resistance of composites, rather than the hardness of matrices.
5
Rutherford, Keith Leslie. "New methods for characterising abrasion and erosion resistance." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627429.
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Fasahat, F., R. Dastjerdi, and M. R. M. Dastjerdi. "Abrasion Resistance of Ag/SiO2/PA6 Nanocomposite Fabrics." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35638.
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In recent decades, polymeric nanocomposites have been widely used in chemical, automobile and aero industries due to their low weight and smoothness. Abrasion resistance is a vital property in variable ap-plications of polymeric composites. Here, to investigate the wear resistance of nylon 6 nanocomposite fab-rics, melt spun yarns were filled with different concentrations of Ag/SiO2 nanoparticles and the wear prop-erties of weft knitted nanocomposite and pure samples were evaluated. Results disclosed that the wear re-sistance of composite fabrics containing nano-particles increased considerably in comparison to pure one. Therefore, nanoparticles can play an important role in improving the nanocomposite wear resistance.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35638
7
Aslantas, Onur. "A Study On Abrasion Resistance Of Concrete Paving Blocks." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605709/index.pdf.
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Concrete block pavement (CBP) can be an alternative pavement to asphalt and concrete pavements. CBP is formed from individual concrete paving blocks (CPBs) that fit next to one another on a suitable sub base leaving a specific joint space among them to be filled with jointing sand.
CBP differ from other pavements according to their mechanical behavior, manufacturing technique, structural design, installation technique and structural behavior. For a serviceable pavement all of these subjects have to be studied. The literature about the mechanical behavior of CPBs is not adequate. This study aims to determine the performance of CPBs formed from different mixes prepared with a white portland cement.
For this purpose, 10 mixes with different cement contents and W/C ratios and 2 mixes from a commercial CPB manufacturer were tested. The compressive strength,
tensile splitting strength, abrasion resistance, density and % water absorption tests were performed on each mix at 7, 14, 28 days.
It was concluded that, the cement content in the mix, optimum water volume for a given cement content, the way the manufacturing equipment is operated and their interaction was effective on the mechanical properties of CPBs. It was also observed that there was no handicap to stop the abrasion resistance test at 8*22 revolutions instead of 16*22 revolutions given in TS 2824.
8
Elwell, David W. J. "Toughness and abrasion resistance of high alloy cast iron." Thesis, Aston University, 1986. http://publications.aston.ac.uk/11866/.
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Halley, William G. "Evaluating abrasive wear resistance of extruder tooling materials using the dry sand rubber wheel abrasion test." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42102.
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A series of experiments was performed on groups of
samples made from materials currently used to manufacture
tooling for extruders to determine if the ASTM G65 dry sand
rubber wheel abrasion test could be used as an accelerated
test to evaluate candidate materials. Samples were tested in
the heat treated condition and after surface modification by
plasma ion nitriding. The range of materials tested included
medium and high alloy steels and steel bonded carbide
composites. The abrasives used were AFS 50/70 test sand and
Dresser Glasgrain crushed fused silica.
Evaluation of test wear scars and wear debris from the tests using AFS 50/70 showed that delamination was the primary wear mechanism for the composite materials, with some ploughing and microcutting, while ploughing and microcutting were the primary mechanisms in the wear of the steels. Evaluation of parts made from a composite material which were removed from service indicated that matrix erosion was the primary wear mechanism. Tests with Glasgrain fused silica as the abrasive yielded wear scars with the same morphology as the parts returned from service, but the very poor flow characteristics of this material caused inconsistency in the supply of this abrasive to the contact region.
Interrupted tests showed that the wear rate was constant for the steels in the non-nitrided condition. After nitriding, the wear rate increased with test duration. The nitriding was found to act as a barrier coating providing an initial period of very low wear until the nitride layer is broached. The wear rate then increases to approximate the wear rate of the non-nitrided samples.
It was found that the friction force alters the location
of the maximum normal force, shifting the point of greatest
contact force toward the entry end of the wear scar.
Master of Science
10
DiSantis, Nicholas E. "Rub, fold, and abrasion resistance testing of digitally printed documents /." Online version of thesis, 2007. http://hdl.handle.net/1850/4489.
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Smith, Marilyn. "The colouring, sealing and abrasion resistance of anodic oxide coatings." Thesis, London Metropolitan University, 1990. http://repository.londonmet.ac.uk/2981/.
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The service performance of anodised aluminium in architecture is dependent upon the control of the anodising, colouring and sealing processes. The quality of the anodic oxide film is determined by assessment tests. The use of a nitric acid ‘predip’ on soft films was shown to dissolve a soft outerlayer. A new admittance test was devised in which the ‘drift’, Y, was measured using 33%, nitric acid. This test threw light on the sealing quality of films exposed to the environment and those sealed in nickel salt solutions. Well-sealed, hard films gave a Y value of 0.1 to 0.2. A sealing mechanism for nickel acetate solutions is proposed in which ageing of a Ni-A1 complex is thought to play a significant role. The admittance-abrasion (Y-?) profile was used to supplement other test data. An accelated sulphur dioxide test was investigated, the optimum conditions for which were 40°C for 6 hours. The presence of a sealing bloom was determined by a simple go/no go three paper abrasion test. The assumption is made that Yt (25°C ) = a + bt and linear regression has been used to find b. It has been found that for batches having a range of thicknesses but a common sealing time, the linear relation is a reasonable assumption when the gradient is < +10. The admittance values of electrocoloured tin black film s have been found to be anomalous. The gradients are negative due to the presence of tin in the pores. Linear regression has been used to obtain an average value of b over the whole thickness range, which gives information as to the degree of sealing. Colouring and soaking in sulphuric acid at elevated temperatures (before sealing) reduces the abrasion resistance. The abrasive wheel test was also used to show the depth of tin within the pores. The use of the addition agent ‘Tribrite’ in tin colouring solutions suppresses the outward, whiskery growth of tin in the pores.
12
Webb, Martyn. "The Effect of low-grade aggregates on the abrasion resistance of concrete." Thesis, Aston University, 1996. http://publications.aston.ac.uk/14256/.
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Three types of crushed rock aggregate were appraised, these being Carboniferous Sandstone, Magnesian Limestone and Jurassic Limestone. A comprehensive aggregate testing programme assessed the properties of these materials. Two series of specimen slabs were cast and power finished using recognised site procedures to assess firstly the influence of these aggregates as the coarse fraction, and secondly as the fine fraction. Each specimen slab was tested at 28 days under three regimes to simulate 2-body abrasion, 3-body abrasion and the effect of water on the abrasion of concrete. The abrasion resistance was measured using a recognised accelerated abrasion testing apparatus employing rotating steel wheels. Relationships between the aggregate and concrete properties and the abrasion resistance have been developed with the following properties being particularly important - Los Angeles Abrasion and grading of the coarse aggregate, hardness of the fine aggregate and water-cement ratio of the concrete. The sole use of cube strength as a measure of abrasion resistance has been shown to be unreliable by this work. A graphical method for predicting the potential abrasion resistance of concrete using various aggregate and concrete properties has been proposed. The effect of varying the proportion of low-grade aggregate in the mix has also been investigated. Possible mechanisms involved during abrasion have been discussed, including localised crushing and failure of the aggregate/paste bond. Aggregates from each of the groups were found to satisfy current specifications for direct finished concrete floors. This work strengthens the case for the increased use of low-grade aggregates in the future.
13
OLIVEIRA, Marcelo dos Anjos. "Desgaste abrasivo do aço Hadfield com diferentes teores de carbono em abrasômetro do tipo pino-disco." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18671.
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A presente pesquisa teve como objetivo, investigar o efeito do teor de carbono e do tamanho do abrasivo na resistência ao desgaste e no fenômeno de encruamento superficial de quatro aços Hadfield. Para esse estudo, foi montado, o equipamento pino contra disco, e, como abrasivo utilizou-se lixas de ferro, com o tamanho médio entre 36 µm e 93 µm. Para o alcance do objetivo proposto foram delimitados materiais e métodos, a saber: (a) montagem do abrasômetro pino-disco a partir de um dispositivo desativado disponibilizado pelo LFS-USP; (b) confrontar resultados experimentais – dois materiais (Aço 1045 e alumínio 6351) foram submetidos a ensaios realizados na UFPE e USP para fins de estudos comparativos; (c) avaliação da influência de parâmetros do ensaio – três abrasivos com diferentes tamanhos de partículas e diferentes cargas foram submetidos e avaliados mediante o desgaste abrasivo; (d) avaliação do comportamento de diferentes composições do aço Hadfield perante ensaios de abrasividade – aços contendo quatro diferentes teores de carbono foram submetidos a ensaios com lixas #220 e #320; (e) análise das superfícies desgastadas – após os ensaios dos materiais, as superfícies foram realizadas análises por microscópio eletrônico de varredura (MEV) das superfícies desgastadas. Os resultados obtidos com o equipamento na metodologia empregada tiveram uma boa reprodutibilidade. Foram observadas diferenças nos resultados entre os equipamentos da UFPE e da USP. Quanto a este tópico, o desgaste abrasivo do aço Hadfield foi influenciado pelo teor de carbono apresentando uma relação em que maiores teores demonstraram menor efeito de desgaste, diferentes tamanhos de abrasivo ocasionam um efeito de encruamento significativo, onde se observou o ganho de dureza em aços com menores teores de carbono. Contudo, foi apresentada uma oscilação do efeito no abrasivo #320. As micrografias revelaram microssulcos e microcortes provenientes do ensaio e não foram observadas diferenças nas marcas de desgaste quando utilizados tamanhos diferentes de partícula abrasiva. Ao final, chegou-se a conclusão de que os resultados obtidos demonstram que o teor de carbono influência na resistência ao desgaste do aço e consequentemente no encruamento superficial do aço. Observa-se também a influência do tamanho do abrasivo e carga aplicada o ensaio.
This research aimed to investigate the effect of the carbon content and the size of the abrasive in the wear resistance and surface hardening phenomenon four Hadfield steel. For this study , has been assembled , the disc against pin device and abrasive was used iron sandpapers, with average size between 36 m and 93 micrometers. To achieve the proposed objectives were defined materials and methods, namely: (a) mounting the pindisk abrasômetro from a disabled device provided by the LFS-USP; (b) comparing experimental results - two materials (1045 steel and aluminum 6351) were submitted to tests performed at university and USP for purposes of comparative studies; (c) evaluation of the influence of the test parameters - Three abrasive particles with different sizes and different loads were submitted and evaluated by the abrasive wear; (d) assessment of the behavior of different steel compositions Hadfield before abrasiveness tests - steels containing four different carbon contents were subjected to tests with sandpaper # 220 and # 320; (e) analysis of the worn surfaces - after the tests of materials different analyzes were performed by scanning electron microscope (SEM) of worn surfaces. The results obtained with the equipment in the methodology employed had good reproducibility. There were differences in results between the equipment and the UFPE USP. On this topic, the abrasive wear Hadfield steel was influenced by carbon having a relationship in which higher levels showed less wear effect, different abrasive sizes cause a significant strain hardening effect, which was observed gain hardness steel with lower carbon content. However, an oscillation of the abrasive effect on the # 320 was presented. The micrographs revealed microssulcos and microcuts from test and differences were observed in wear marks when using different sizes of abrasive particle. In the end, came to the conclusion that the results show that the influence of carbon content in the wear resistance of steel and consequently the surface of the steel hardening. It is also observed the influence of abrasive size and load applied to the test.
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Kirtley, Neil. "Interfacial and polymer chemistry of methacrylate based composite materials." Thesis, University of Sunderland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302675.
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Melo, Juan Carlos Pontons. "Avaliação do desgaste por escovação, in vitro, de uma resina composta, fotopolimerizada por lâmpada halógena, em dois diferentes tempos." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-29052009-094511/.
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Um dos principais problemas dos materiais restauradores (incluindo a resina composta) é o desgaste por abrasão. Portanto, o objetivo neste trabalho foi avaliar in vitro o desgaste abrasivo por escovação da resina composta 4Seasons, de duas cores diferentes (A3 e C4) e com fotopolimerização por dois diferentes tempos (20 e 40 s), utilizando escova Sorriso, da Colgate, e creme dentifrício Colgate Tripla Ação; também foi usado, como material de referência, o polimetil metacrilato. Assim, foram confeccionados dez corpos-de-prova, para cada um dos cinco grupos formados (PMMA, A3 20s, A3 40s, C4 20s, C4 40s). Cada espécime consistia basicamente num cilindro de cerca de 1,8 mm de altura e 8 mm de diâmetro. Cada espécime, após sua confecção, era imerso em água deionizada, a 37 ± 2 ºC, por 24 horas, quando então eram regularizados com lixa (granulação # 600 e # 1.000); após lavagem com ultrassom, voltavam a ser armazenados nas mesmas condições, até completar-se um período de uma semana. A escovação foi então efetuada numa máquina própria, que comportava dez espécimes simultaneamente, sendo de 3 N a carga de cada escova sobre o respectivo espécime; a velocidade de cada escova era de 18 cm/s, com a freqüência (ida e volta, num percurso total de 4 cm) de 4,5 ciclos/s; o período de escovação de um espécime compreendia 150. 000 ciclos. Foram efetuados cinco períodos (ou lotes) de escovação, de modo que um espécime do material de cada grupo tivesse sido submetido à ação de cada uma das posições ocupadas pelas dez escovas. A quantidade de massa perdida, para cada espécime, foi calculada por meio de pesagem (pré e pós escovação), numa balança com acuidade de milionésimo de grama. O trabalho foi também ilustrado com gráficos de rugosidade e com fotomicrografias tomadas ao MEV. A taxa média de desgaste foi de 2,8 mg para o PMMA, de 5,5 mg para o A3-20s, 4,7 mg para o A3-40 s, 5,4 para o C4-20s e 4,2 mg para o C4-40s; a respectiva análise de variância mostrou não existir diferença significante entre os grupos, para p=0,166; o coeficiente de variação entre os grupos foi bastante semelhante. Foi possível concluir que não existiu diferença da resistência ao desgaste abrasivo entre os grupos estudados.One of the main problems of dental restorative materials (including the resin composites) is the abrasion wear. Therefore, the aim of this work was to evaluate in vitro the abrasive wear by toothbrushing of the resin composite 4Seasons, of two different colors (A3 and C4), cured by two different times (20 and 40 s), using a toothbrush (Sorriso - Colgate), and a dentifrice (Tripla Ação Colgate). Polimetil meth-acrylate was used as reference material. Ten cylindric samples (approximately 1.8 mm height and 8 mm diameter) had been prepared for each one of the five evaluated groups (PMMA, A3 20s, A3 40s, C4 20s, C4 40s). After confection, samples were immersed in deionized water, at 37 ± 2ºC, for 24 h, and then regularized by abrasive gritting with sandpaper (from #600 to # 1 000); after that, were cleaned in ultrasound bath, and restored to the same described conditions, until completing the period of one week. The toothbrushing was then conducted in a proper machine that holds 10 specimens simultaneously, with a 3 N load of each toothbrush on the respective sample. The speed of each toothbrush was of 18 cm/s, at a frequency of 4.5 cycles/s (each cycle consisting of 2 cm forward and 2 cm backward). 150. 000 cycles were applied per sample. Five periods (or lots) of toothbrushing had been performed, in a way that one sample of each group had been submitted to the brushing action at one position in the machine. The amount of weight loss for each sample was calculated by means of weighting (before and after toothbrushing), in an analytical balance with accuracy of millionth of gram. Roughness and MEV photomicrographies were also evaluated. The average rate of wear was of 2.8 mg for PMMA, 5.5 mg for A3-20s, 4.7 mg for A3-40 s, 5.4 for C4-20s, and 4,2 mg for C4-40s. One-way ANOVA showed no significant difference between groups (p = 0.166). The coefficient of variation between the groups was sufficiently similar. It was possible to conclude that difference of the resistance to the abrasive wear between the studied groups did not exist.
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Garcia, Fernanda Cristina Pimentel. "Avaliação comparativa de resinas compostas fluidas em relação a resistência à abrasão (escovação simulada)." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/25/25131/tde-24042001-085909/.
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O presente estudo procurou analisar, através de um teste de abrasão in vitro por escovação simulada, a perda de massa e a alteração da rugosidade superficial em resinas compostas "fluidas" e resinas compostas controles. As marcas comerciais utilizadas foram: Aeliteflo-Bisco (A), Natural Flow-DFL (N), Wave-SDI (W), Flow-It Lf-Jeneric/Pentron (FLf) e Flow-It-Jeneric/Pentron (F). Uma resina composta de partículas híbridas Z100-3M (Z) e uma de micropartículas Silux Plus-3M (S) foram utilizadas como controle. Foram confeccionados 84 corpos-de-prova, de 5mm de diâmetro e 3mm de espessura, sendo 12 para cada marca comercial utilizada. Para o acabamento e o polimento dos corpos-de-prova foram utilizados discos Sof-Lex (3M) nas granulações fina (cor azul média) e superfina (cor azul claro), por tempo médio de 15/20 segundos, para cada granulação, em baixa velocidade. Para os ensaios de abrasão, foi utilizada uma máquina apropriada associada à escova Colgate Classic Infantil (Colgate-Palmolive) de cerdas macias e solução do creme dental, Colgate Proteção Anticáries com MFP (Colgate-Palmolive), diluído em água deionizada na proporção de 1:2. No teste in vitro, foram realizados aproximadamente100.000 ciclos. A determinação do desgaste dos materiais foi verificada pela quantidade de massa perdida após os ensaios, com a utilização de uma balança analítica Sartorius. A rugosidade foi determinada quantitativamente na superfície dos corpos-de-prova, com o auxílio de um rugosímetro Hommel Tester T 1000, comparando a diferença obtida após os testes de escovação e, qualitativamente, por microscopia eletrônica de varredura. Os resultados foram analisados pela variância a um critério ANOVA e pelo Teste de Tukey com p<0,05. Pelo coeficiente de Pearson não foi verificada correlação (r=-0,0296) entre porcentagem de perda de massa e rugosidade de superfície. Os materiais não apresentaram diferenças estatisticamente significantes quanto à alteração de massa, somente quanto à rugosidade superficial. A resina A apresentou a maior alteração de massa, (3,77%), seguida da resina de micropartículas S (3,04%). Em contrapartida, a resina híbrida convencional Z apresentou a menor alteração de massa (1,29%), ficando o restante das resinas "fluidas" com alteração intermediária a estas três resinas. A maior alteração de rugosidade foi verificada para a resina W (1,1720mm), com diferenças estatisticamente significantes em relação às outras resinas testadas: S (0,2749mm), Z (0,2495mm), FLf (0,1597mm), F (0,1217mm), N (0,0620mm) e A (0,0505mm).This research aimed to assess the wear of flowable resin composites through an in vitro simulated toothbrushing abrasion test. The weight loss and surface roughness analysis were performed using five commercial brands: Aeliteflo, Flow-It, Flow-It Lf, Natural Flow and Wave. Hybrid Z-100 and Microfilled Silux Plus composites have been included as controls. Twelve samples (discs) of each material were prepared with 5mm thickness and 3mm in diameter. The test was performed up to 100.000 cicles with an appropriate machine containing soft bristles tips, dentifrice solution and deionized water in order to simulate toothbrushing. The weight loss was determined by the differences between the initial and final weights ( before and after toothbrushing) using a Sartorius analytical scale. After 5 readings, in a T 1000 Hommel testing machine, the evaluation of surface roughness was obtained by the differences between initial and final means. The analyzed ( ANOVA and Tukey, p< 0,05) results showed that Silux Plus, Flow-it, Wave, Flow-It Lf and Natural Flow had an intermediate weight loss (3,04; 2,70; 2,19; 2,12 and 2,04% respectively). Z-100 exhibited the lowest (1,29%) weight loss, whereas Aeliteflo, the highest (3,77%). Wave showed the highest surface roughness variation (1,1720mm), statistically different from the other groups, which exhibited the following differences: Silux Plus (0,2749mm), Z-100 (0,2495mm), Flow-it Lf (0,1597mm), Flow-It (0,1217mm), Natural Flow (0,0620mm) and Aeliteflo (0,0506mm). Aeliteflo presented the highest weight loss and the lowest surface roughness difference; on the other hand, Wave showed the highest surface roughness difference and an intermediate weight loss when compared with the other tested resins.
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Kaya, Derya. "Effect Of Resin And Fiber On The Abrasion, Impact And Pressure Resistance Of Cylindrical Composite Structures." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613287/index.pdf.
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The aim of this study was to investigate the effects of resin and fiber on the abrasion, impact and internal pressure resistances of fiber reinforced plastic composite pipes produced by continuous filament winding method. For this study, pipe samples were produced with different combinations of resin type, fiber type, fiber amount and fiber length. All the samples were tested in accordance with the related ISO (International Organization for Standardization), DIN (German Standardization Institution) and BSI (British Standards Institution) standards. Three types of resins were used as ortophthalic, isophthalic and vinylestertwo types of fibers were used as E-glass and ECR-glass and one type of GLASSFLAKES was used as C-glass. It was observed that the type of resin did not have any significant effect on burst pressure. However, the vinylester resin had a considerable positive effect on the abrasion and impact resistances. Moreover, it was observed that the type of fiber did not have any significant effect on impact and internal pressure resistances, but the use of C-glass GLASSFLAKES resulted in a positive effect on the abrasion resistance. Additionally, it was found that the increase in the amount of glass fiber resulted in increase of burst pressure, impact and abrasion resistances. Finally, it was observed that the length of glass fiber did not have any significant effect on abrasion resistance, but the decrease in fiber length resulted in a higher internal pressure and impact resistances.
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Mahmoud, Enad Muhib. "Development of experimental methods for the evaluation of aggregate resistance to polishing, abrasion, and breakage." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/4959.
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Aggregate properties influence different aspects of asphalt pavement performance. Aggregate polishing characteristics are directly related to pavement surface frictional properties and thus to skid resistance. Aggregate resistance to degradation (abrasion and breakage) is another important property that influences pavement performance. Aggregate degradation could take place during production due to plant operations and during compaction, leading to change in aggregate characteristics and mix properties. In addition, aggregate resistance to degradation is important in mixes such as Stone Matrix Asphalt (SMA) and Open Graded Friction Course (OGFC) that rely on stone-to-stone contacts among coarse aggregates. Some aggregates in these mixes fracture due to the high stresses at contact points. Many test methods exist for measuring aggregate polishing and degradation, but a critical review of these methods reveals that they suffer from being time consuming, are unable to differentiate between aggregates with distinct resistance to polishing, or unable to differentiate between aggregate resistance to abrasion and breakage. New methodologies are needed to give better assessment of aggregate resistance to polishing, abrasion, and breakage. The thesis presents the development of new methods for measuring aggregate resistance to polishing, abrasion, and breakage. These methods rely on measurements using the Aggregate Imaging System (AIMS) and Micro-Deval. The new method for measuring aggregate resistance to polishing monitors change in aggregate texture as a function of polishing time. As such, it provides the initial texture, rate of polishing, and final texture. The new method for measuring aggregate degradation is capable of distinguishing between breakage and abrasion. In this method, abrasion is defined as the reduction in aggregate angularity, while breakage is defined by fracture of particles. The new methods are shown to be rapid and accurate, and they require reasonable training. Since both AIMS and Micro-Deval are used in the new methods, it was necessary to evaluate the repeatability of these two methods. Measurements using two AIMS units and two Micro-Deval machines were used to assess the variability. There was no statistical difference between the measurements of the two AIMS units or between the measurements of the two Micro-Deval units.
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Poyo, Myezo. "Abrasion resistance of IV-RCC used to construct spillway concrete steps of South African dams." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29533.
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This dissertation outlines the investigation on abrasion resistance of roller compacted concrete designed for the spillway steps of dams owned by the Department of Water and Sanitation. Literature on abrasion resistance of concrete has been reviewed and factors affecting abrasion resistance are discussed. Among these include hardness of concrete, aggregate/paste bond, type of aggregates, concrete compressive strength, curing, surface treatment and the quality of the concrete surface which is influenced by the finishing method. Available test methods as outlined by ASTM International Standards are also discussed in the literature review but only two methods (sandblasting method and wire brush method) were used in this research. These have been chosen because of their availability (at the UCT Civil Engineering Laboratory) and relevancy to this research. The sandblasting method is the most relevant in this research because it stimulates similar abrasion action as waterborne action on the concrete surface. The other method has been chosen for its availability in the UCT lab, to compare its results with the sandblasting results, and to evaluate whether if it can be used to assess abrasion resistance of hydraulic structures. A two-way experimental approach was adopted to achieve results for this research. The first approach was a laboratory investigation, where concrete cubes were produced under controlled conditions and tested for abrasion resistance, compressive strength, oxygen permeability index (OPI) and Sorptivity test. The durability index tests were conducted to get a general evaluation of the concrete’s microstructure. If the OPI values are acceptable (more than 9) then the concrete’s general microstructure would be accepted to be durable. Materials (aggregates) from De Hoop Dam and those readily available at the UCT laboratory were used to cast different types of concrete to be investigated and compared. The types of concrete included conventional concrete, fly ash concrete and slag (GGBS) concrete. DWS uses fly ash in the majority of their mass concrete projects due to its pozzolanic properties which help slowing down the heat of hydration. The slag was included in these mixes in order to have available results when it is used in future projects as it is highly likely to be used for areas in the KwaZulu-Natal province which have a less reactive type of slag in terms of heat of hydration. The raising of the Hazelmere Dam, close to Durban, is currently using GGBS as an extender. The second approach of this research was based on abrasion testing of cores drilled from the stepped wall of De Hoop Dam. These cores were drilled and taken to UCT laboratory for investigations with the same test methods used for laboratory cubes. A comparison was drawn between the test results of the laboratory made cubes and those drilled from the dam spillway, and a correlation was investigated between these two. Furthermore, the sandblast test method was compared with the wire brush method to assess which one produces more reliable results. The abrasion results showed small differences in abrasion resistance performance between the conventional concrete and the roller compacted concrete mixes. In fact when the percentage of the extender was adjusted from 70% to 65% these two concrete mixes performed equally. It was confirmed that beyond 45% replacement of Portland cement with fly ash, there is no improvement in abrasion resistance of concrete. However, there were no significant differences between abrasion resistant values of concrete with 45% or 65% fly ash replacements. It was observed that abrasion resistance of concrete was compromised beyond 65% fly ash replacement. Aggregates with sub-angular shape and rough texture have proven to yield high abrasion resistant concrete. The concrete made with blends of GGBS and Portland cement showed slightly improvement in abrasion resistance of concrete when compared to fly ash concrete. The cores drilled from the structure had abrasion resistance values 3 times more than the laboratory produced cubes and this was consistent with both the sandblasting and wire brush method, indicating that the actual structure has adequate abrasion resistance. The sandblasting method has proven to be reliable and more sensitive and it is recommended for assessment of abrasion resistance of hydraulic structures, while the wire brush method can be used for general quality control. Recommendations based on the results and literature study will be made available to the Department of Water and Sanitation to update their specifications, which was one of the key goals of this research.
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Gatzanis, Gustav Ernest. "Abrasion-corrosion and stress corrosion resistance of a 9Cr-2Ni-0.7Mo steel in simulated mine water." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/21957.
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Bibliography: pages 101-109.The locally (RSA) developed 9Cr-2Ni-0.7Mo steel designated 927 formed the subject of this study. Its abrasion-corrosion and stress corrosion performances were assessed in laboratory tests simulating the underground environment in South African gold mines. The results indicate that the alloy performs favourably in abrasive-corrosive applications, outperforming several other higher chromium containing steels which have been designed for the purpose. The alloy is also highly resistant to sec at free corrosion potential in simulated mine water. The good abrasion-corrosion resistance is attributed to the adequate corrosion resistance of the alloy acting in conjunction with the favourable combination of strength and toughness afforded the alloy by its fine grain size and microduplex microstructure of martensite and interlath retained austenite. The production variables of plate thickness and prior cold working were found to exert negligible influence on corrosion-abrasion resistance. This is ascribed to the small influence of these processes on the hardness and associated mechanical properties due the inherent low work hardening ability of the alloy. Slow strain rate (SSR) stress corrosion cracking tests were performed on the alloy in four microstructural conditions viz. as-rolled, tempered, welded and post weld heat treated. The material showed an immunity to sec in all the microstructural conditions for tests conducted at open circuit potential. This apparent immunity is attributed to the difficulty in initiating sec by pitting on the plain specimens over the relatively short test durations. Polarisation to extreme cathodic potentials (-1200m V) resulted in hydrogen embrittlement of this high strength alloy with failure predominantly along prior austenite grain boundaries. Anodic potentials in the excess of OmV induced tunnel-like corrosion pitting attack. Fractographical evidence of sec at the base of these pits indicates the development of the conditions necessary for sec within the pit confines. This is cited as evidence in support of the hypothesis of sec initiation difficulty.
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Schotter, Daniel Keith 1955. "The effects of heat treatment on microindentation hardness, abrasion and corrosion resistance of electroless nickel coatings." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276928.
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A study has been carried out to investigate the effects of heat treatment on microindentation hardness, abrasion and corrosion resistance of Electroless Nickel coatings. In particular, a proprietary coating system, NIKLAD 794 has been investigated. Samples of 4130 steel have been plated according to manufacturer's specifications. The plated samples have then been subjected to an array of heat treatment temperatures and times. Post heat treatment tests have been conducted including Taber Abrasion testing, salt fog chamber testing, and Knoop microindentation hardness testing. Results of the individual tests have been compared to determine the effects of heat treatment on, and the interactions between, the parameters examined.
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Marques, Flávio Parreiras. "Comportamento tribológico de três superligas de cobalto em ensaios de microabrasão." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-02052018-141619/.
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As superligas à base de cobalto são bem conhecidas por sua excelente resistência ao desgaste. Muitas pesquisas reportadas na literatura abordam o comportamento do desgaste destas ligas, seja no desgaste por deslizamento, erosivo ou abrasivo. Não obstante, o desgaste microabrasivo destas ligas não tem sido muito investigado, apesar dos danos causados por este tipo de solicitação. O comportamento do desgaste microabrasivo de três superligas à base de cobalto: a) 48% Co, 29 %Cr, 19 % Fe; b) uma liga com composição química próxima à da liga comercial Tribaloy T400 (Co 56 %, Cr 8.5%, Mo 29% Si 3.3 %) e c) uma liga com composição próxima à da liga comercial Stellite 6 (Co 64%, Cr 24 %, W 4.2 %, C 2,3%) foram investigadas. Os ensaios de microabrasão foram conduzidos com três abrasivos SiO2, Al2O3, e SiC em suspensão em água destilada, com concentração de 0,1 g/cm3. A carga aplicada foi de 0,3 N, a velocidade angular 20 rpm e a distância total de deslizamento, 48 metros. A análise das superfícies desgastadas por microscopia óptica, eletrônica de varredura e por perfilometria de contato mostraram que o tamanho, forma e dureza dos abrasivos podem influenciar significativamente os coeficientes de desgaste. Os ensaios conduzidos com partículas abrasivas de SiC e Al2O3 apresentaram maiores coeficientes de desgaste que os conduzidos com partículas de SiO2. A Liga Co-Cr-Fe mostrou os maiores coeficientes de desgaste quando comparada com as demais ligas, devido à baixa fração volumétrica de partículas de segunda fase, duras, precipitadas em sua microestrutura. Durante os ensaios, as três ligas, ensaiadas com os três diferentes abrasivos, apresentaram coeficientes de desgaste crescentes com o aumento da dureza do abrasivo; observou-se uma variação linear dos coeficientes de desgaste com a razão entre a dureza do abrasivo (Ha) e a dureza composta da liga (Hs), com R2 = 0.74. O micromecanismo dominante em todos os ensaios foi o desgaste abrasivo a dois corpos (grooving wear). A liga com composição próxima à da liga comercial Tribaloy T400, contendo fases de Laves dispersas em sua microestrutura, apresentou uma transição de micromecanismo de desgaste dúctil para frágil, quando submetida a ensaios com partículas abrasivas de Al2O3. Assim sendo, o volume de material removido nesta liga foi ligeiramente maior que o observado no ensaio com partículas de SiC. Na liga contendo baixa fração volumétrica de partículas de segunda fase, com matriz constituída por Co (CFC), observou-se uma camada subsuperficial nanocristalina de aproximadamente 1 µm de espessura, severamente deformada, imediatamente abaixo da superfície desgastada. Concluiu-se que o desgaste microabrasivo induziu a recristalização a frio do material encruado, com formação de grãos equiaxiais de dimensões nanométricas.Cobalt alloys are well known for their excellent wear resistance. Many investigations are reported in literature related to the behavior of erosive, abrasive or sliding wear of these alloys. Nevertheless, the micro-abrasive wear of these alloys has not been thoroughly investigated, despite the damage caused by this type of wear. The microabrasive wear behavior of three cobalt alloys: a) 48 wt.% Co, 29 wt.% Cr, 19 wt.% Fe; b) an alloy with chemical composition close to Tribaloy T400 (56 wt.% Co, 8.5 wt.% Cr, 29% wt. Mo, 3.3 wt. %Si) and c) an alloy with chemical composition close to Stellite 6 (64wt.% Co 24 wt.% Cr, 4.2 wt.% W, 2,3 wt.% C were investigated. The tests were carried out using three 0,1 g/cm3 slurries composed by SiO2, Al2O3, and SiC particles, in suspension in distilled water. The applied load was 0.3 N, the rotational speed 20 rpm and the total sliding distance 48 m. Analysis of the worn surfaces of the tested alloys by Optical Microscopy, Scanning Electron Microscopy and Contact Stylus Profilometry showed that abrasive size, shape and hardness could significantly influence the wear coefficients. The tests carried out with SiC and Al2O3 slurries resulted in greater wear rates than those carried out in SiO2 slurry. Stellite 250, showed the greatest wear coefficient, compared to the two other experimental alloys, due to a very low volume fraction of hard second phase particles in the microstructure. Wear coefficients decreased with increasing abrasive particles hardness. An approximate linear correlation with the ratio between the hardness of the abrasives (Ha) and the compound hardness of the alloys (Ha) with a correlation factor R2= 0.74. The dominant wear micromechanism observed in all tests was two-body abrasion (grooving wear). The modified T400 alloy, containing Laves phase showed a transition from ductile to brittle wear mechanisms when testing with alumina slurries. The worn volume was slightly greater than the one observed with SiC. A severely deformed nanocrystalline layer was identified, immediately below the worn surface. It was concluded that cold recrystallization of the work-hardened material occurred, with the formation of nano sized equiaxed grains.
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Silva, Cristina Vitorino da. "Estudo da influência das propriedades relacionadas à superfície e à matriz na resistência à abrasão de concretos para pisos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/139378.
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O desgaste superficial por abrasão é uma manifestação patológica que decorre do atrito entre partículas secas e a superfície do material, causando uma perda progressiva das camadas mais externas da estrutura. Entender esse mecanismo de deterioração e ainda os parâmetros que influenciam a sua ocorrência são preocupações válidas, visto que ele compromete a durabilidade e a funcionalidade de estruturas, tais como pisos de concreto. Além disso, a correção desta manifestação patológica exige gastos elevados com reparo ou substituição do concreto e, dessa maneira, a necessidade de maiores estudos buscando ações mais efetivas na prática é justificada. Neste particular, estudou-se a influência das propriedades relacionadas à matriz e à superfície na resistência à abrasão dos compósitos. Para tanto, alguns fatores que influenciam na qualidade dos concretos empregados em pisos, como o tipo de cimento (CP IV; CP V-ARI), a relação água/aglomerante (0,40; 0,60), o teor de substituição de sílica ativa (0%; 10%) e o tipo de cura (submersa; caixa aquecida) foram avaliados. Os ensaios adotados para estudar a influência das propriedades de massa no mecanismo de degaste foram os de resistência à compressão uniaxial, resistência à tração na flexão e exsudação. Já os ensaios para verificar a influência das propriedades de superfície na magnitude desse mecanismo foram os de dureza superficial, resistência à abrasão, porosimetria por intrusão de mercúrio, microdureza por indentação, análises em microscópio estereoscópico e a digitalização tridimensional à laser. Os resultados encontrados mostraram uma influência estatística significativa do tipo de cimento sobre todas as propriedades avaliadas, sendo que o cimento de alta resistência inicial apresentou melhor desempenho em comparação ao cimento pozolânico, considerando uma mesma idade de análise (63 dias). Além disso, verificou-se uma influência estatística significativa da relação a/agl no comportamento dos concretos, onde a relação a/agl 0,6 aumentou os índices de desgaste das amostras em relação as de referência (a/agl 0,4), conforme esperado. Quanto ao tipo de cura, os compósitos curados de forma submersa apresentaram os melhores resultados frente ao desgaste superficial comparando-se àqueles mantidos na cura em caixa aquecida. Finalmente, analisando o teor de substituição de sílica ativa, observou-se que a substituição de 10 % sobre a massa de cimento proporcionou acréscimos estatisticamente significativos na resistência à abrasão das amostras com menor relação a/agl; somando-se a isto, a presença da sílica minimizou o efeito da cura em caixa aquecida na camada superficial das amostras de concreto submetidas ao desgaste. Concluindo, a resistência à abrasão dos concretos mostrou ter uma importante relação não somente com as suas propriedades de massa, mas também com a qualidade da sua camada superficial, uma vez que apresentou forte correlação com as características de superfície avaliadas, como a dureza superficial, a microdureza e a porosimetria ao mercúrio. Além disso, salienta-se que o ensaio de dureza superficial por esclerometria poderia ser adotado como parâmetro para determinação direta da resistência ao desgaste e sugere-se que a exsudação dos pisos de concreto venha a ser o fator principal no controle da qualidade da camada superficial da placa de concreto.Surface abrasion wear is a pathological manifestation triggered by friction between dried particles and the surface of the material, provoking a progressive loss of the outermost layers. The comprehension of this mechanism of deterioration and also the parameters that influence its occurrence are valid concerns, since it compromises the durability and functionality of structures such as concrete floors. In addition, repair this pathological manifestation or replace the damage concrete require high expenditure. Thus, the necessity of further studies seeking for practical effective actions is justified. In this particular, the aim of this work was to study the influence of properties related to the matrix and the surface of composites on abrasion resistance. For this purpose, some factors that influence the quality of the concrete used in floors, including the cement type (CP IV; CP V-ARI), the water / binder ratio (0.40, 0.60), the replacement content of silica fume (0%, 10%) and the conditions of cure (submerged; heat box) were evaluated. The assays employed in order to study the influence of mass properties on the wear mechanism were the compressive strength, flexural tensile strength and bleeding. As regards to the influence of surface properties on the magnitude of this mechanism, it was verified by testing the surface hardness, abrasion resistance, porosimetry by mercury intrusion, microhardness by indentation, analysis in stereoscopic microscope and three-dimensional laser scanning. The obtained data demonstrated a statistically significant influence of cement type on all assessed properties, with the high early strength cement presenting a better performance as compared to pozzolan cement, considering a similar age of analysis (63 days). Furthermore, there was a statistically significant influence of water / binder ratio on concrete behavior, where the water / binder ratio of 0.6 increased the wear rates of the samples in comparison to the reference (water / binder 0.4), as expected. Regarding to the conditions of cure, the submerged composites showed better results against surface wear as compared to those kept in the heat box. Finally, it was observed that the replacement content of silica fume of 10% on the cement mass provided statistically significant increases in abrasion resistance of samples with lower water / binder ratio. In addition, the presence of silica minimized the effects of curing in a heat box on the surface layer of concrete samples that were submitted to wear. In conclusion, the abrasion resistance of concretes demonstrated an important relationship not only with the mass properties of these structures but also with the quality of their surface layer, since a strong correlation with the evaluated surface features was observed, including surface hardness, microhardness and porosimetry by mercury intrusion. Moreover, it is emphasized that the surface hardness assay by rebound hammer may be used as a parameter for direct determination of wear resistance and it is suggested that bleeding of concrete floors might be the main factor for controlling the surface layer quality of the concrete slab.
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Cordesman, Alexander. "MECHANICAL ABRASION AND ELECTROPORATION IN THE TRANSFORMATION OF INTACT PLEUROTUS OSTREATUS HYPHÆ and NUTRIENT-DEPENDANT RESISTANCE TO HYGROMYCIN B." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/173.
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ABSTRACT 1: Abrasive treatment and subsequent electroporation of the basidiomycete Pleurotus ostreatus in a hypertonic buffer was investigated as a potential method of transforming of intact hyphæ. Mycelia, which are not capable of being transformed via electroporation due to interference by the cell wall, were abraded in an attempt to mechanically degrade the cell wall prior to electroporation. An electroporation field strength of 12,500 V/cm for 500 μs to 1.25 ms was found to be optimal based upon mortality effects. A 32 μm carborundum abrasive was initially evaluated but was quickly found to be inappropriately large so a corundum abrasive with an average size of 300 nm was focused on. Vortexing as well as low and medium power ultrasonic agitation with the corundum abrasive were investigated for their potential to cause mechanical degradation of the cell walls. Vortexing and low power sonication were found to be ineffective at causing adequate degradation while medium power sonication was found to be both ineffective and super lethal. While the possibility of mechanical abrasion facilitating transformation via electroporation remains, it is unlikely that conventional methods of agitation will be effective. ABSTRACT 2: The dose response of the basidiomycetes Pleurotus ostreatus, Agrocybe aegerita and Cordyceps millitaris to the antibiotic hygromycin B was tested on two common and one in-house solid growth media. The three species were grown on Potato dextrose agar, malt extract agar and an agar containing maltose, yeast-extract, peptone and glucose with concentrations of hygromycin B from zero to 100 μg/ml for 11 to 14 days. Micrometer measurements were used to determine the growth rate of each species on each media. Significant differences in hygromycin B tolerance for each species between the three media types were evident (p-value < .0001 by ANOVA for all). Neither the media type nor the growth rate on hygromycin B free plates were useful predictors of effective hygromycin B doses so optimization should be performed on every strain and media type used for selection.
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Černá, Hana. "Sledování vlivu složení betonu na odolnost proti abrazi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392338.
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This diploma thesis focuses on the resistance of concrete to abrasion with regard to the raw materials used for their production. In the theoretical part of the thesis are described admixtures, different types of aggregate and aggregate composition which influence the resistance of concrete to abrasion. In the experimental part, 15 different C30 / 37, S4 concrete formulations were proposed. Different types of aggregates - fecal gravel (Žabčice), biotic granodiorite (Olbramovice) and amphibolite (Želešice) have always been used in the recipes. Fine ground limestone, micro-silica, high-temperature fly ash and finely ground slag were ingredients that were added to the proposed recipes. Consistency was determined by the method of cone seating and the density of fresh concrete. In the hardened state, concrete density, compressive strength, bending tensile strength, tensile strength, watertightness, concrete absorption, and abrasion resistance were determined using the Böhm method and wide wheel method. The test specimens were tested after 7, 28, and 90 days of maturation.
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Mello, Pâmela Carbone. "Avaliação da resistência à abrasão, microdureza superficial e estabilidade de cor de dentes artificiais de resina acrílica." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/58/58131/tde-28032008-174332/.
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O objetivo deste trabalho foi avaliar in vitro a resistência a abrasão, a microdureza superficial e a estabilidade de cor de dentes artificiais de resina acrílica. Sete grupos (1- Biolux, 2- Trilux, 3- Blue Dent, 4- Biocler, 5- Orthosit-Vivodent, 6- Postaris-Antaris, 7- Gnathostar-Ivostar), compostos de 12 pre-molares superiores de cada fabricante, sendo 6 contra antagonistas metálicos (Ni-Cr) e 6 contra antagonistas de resina indireta (Solidex), foram delineados em um perfilômetro, antes e após serem submetidos ao ensaio de abrasão. A diferença linear entre a primeira e a segunda leitura foi medida com um paquímetro digital (precisao 0,01mm). Após a análise estatística (análise de variância, teste de Tukey-Kramer, nível de significancia em p<0,05), observou-se que houve diferenças estatísticas significantes entre os grupos e que a marca Postaris apresentou os menores valores de desgaste contra ambos os antagonistas (R=2,33±0,91µm e M=1,78±0,42µm). Para a análise da microdureza superficial Vickers, foram utilizados 6 incisivos laterais superiores de cada marca e 3 leituras (terços incisal, médio e cervical) foram feitas com o auxílio de um microdurômetro. As médias de microdureza superficial Vickers foram submetidas a análise estatística (nível de significancia p<0,05) e com os resultados obtidos concluiu-se que o grupo Biolux (22,1±0,91VHN) seguido do Antaris (21,9±1,58VHN), Ivostar (21,1±0,98VHN) e Biocler (21,0±1,80VHN) apresentaram maiores valores de dureza diferenciando-se do Vivodent (19,1±0,99VHN) e Blue Dent (18,9±1,54VHN), menos duros. Para o ensaio de estabilidade de cor foram utilizados 6 incisivos centrais superiores direitos de cada marca comercial (n=42), submetidos ao processo de envelhecimento artificial acelerado. O aparelho de leitura de cor utilizado foi um Espectrocolorímetro Portátil Modelo Color Guide 45/0 (BYK-Gardner, Alemanha). Cada dente teve sua cor lida antes e imediatamente após o ensaio de envelhecimento artificial. Os valores de ΔE foram submetidos a análise estatística com auxílio do programa JMP 5.1 (SAS Institute, EUA) e mostraram que houve diferenças estatisticamente significantes entres os grupos e que apenas a marca Blue Dent (4,37±0,32) apresentou valores de ΔE>3,3 considerado, segunda a literatura, clinicamente inaceitável. Para os grupos que tiveram alterações clinicamente aceitáveis, o grupo Antaris/Postaris teve a maior variação de cor (ΔE=2,73±0,96) e o grupo Biolux apresentou a menor variação de cor (1,39±0,27). Dentro das limitações da metodologia empregada, concluiu-se que o antagonista utilizado (metal ou resina) influencia a escolha do dente artificial, e que os dentes artificiais testados tem comportamentos diferentes quanto a resistência a abrasão, microdureza superficial e estabilidade de cor.The objective of this work was to evaluate in vitro the abrasion resistance, the superficial microhardness and the color stability of acrylic resin artificial teeth. Seven groups (1-Biolux, 2 - Trilux, 3 - Blue Dent, 4 - Biocler, 5 - Orthosit-Vivodent, 6 - Postaris-Antaris, 7 - Gnathostar-Ivostar), composed of 12 upper premolar for each manufacturer\'s, being 6 against metallic antagonists (Ni-Cr) and 6 against indirect resin (Solidex) antagonists, were delineated in a perfilometer, before and after the abrasion test. The linear difference between the first and the second readings was measured with a digital calliper (0,01mm precision). After the statistical analysis (variance analysis, Tukey-Kramer\'s test, p<0.05), it was observed that there were significant differences among the groups and that the trademark Postaris presented the smallest wear values against both antagonists (R=2,33±0,91µm and M=1,78±0,42µm). For Vickers superficial microhardness, 6 lateral upper incisors of each mark and 3 readings were used (incisal, medium, and cervical thirds) done with the microdurometer. The averages of Vickers superficial microhardness were submitted to the statistical analysis (p<0.05) and the obtained results show that the group Biolux (22,1±0,91VHN) followed by Antaris (21,9±1,58VHN), Ivostar (21,1±0,98VHN) and Biocler (21,0±1,80VHN) presented higher values, differing from Vivodent (19,1±0,99VHN) and Blue Dent (18,9±1,54VHN), less harders. For the color stability test 6 upper right central incisors of each commercial mark were used (n=42), submitted to the accelerated artificial aging process. The apparel for color reading was a Portable Spectruncolorimeter Model Color Guide 45/0 (BYK-Gardner, Germany). Each tooth had his color read before and immediately after the artificial aging. The ΔE values were submitted to the statistical analysis with JMP 5.1 (HEALTHY Institute, USA) software and show that significant differences were found among the groups and that only Blue Dent (4,37±0,32) presented clinically unacceptable values of ΔE (ΔE>3.3). For the groups that had clinically acceptable color alterations, the Antaris/Postaris group had the largest color variation (ΔE=2.73±0.96) and the Biolux group presented to smallest color variation (ΔE=1.39±0.27). Within the limitations of the methodology, was concluded that the antagonist (metal or resin) influence the choice of the artificial tooth, and that the tested artificial teeth have different behaviors for the abrasion resistance, superficial microhardness and color stability.
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Babiuc, Octavian. "Effect of gritting sand quality on road dust pollution." Thesis, KTH, Vägtekniks laboratorium, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194340.
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Pollution of air represents the contamination with matter that can affect both humanhealth and the environment. Road dust has been recognized as a dominant source ofparticulate matter and one of the factors that contributes to its development is the useof gritting sand. Gritting sand is being used during snowy winter conditions as atraction control method. During spring season, when snow and ice melt and surfacesdry out, and the influence of traffic, asphalt surface wear, particle ejection from tires,etc; under the effect of their interaction, cause the formation of particulate matter.A general aim of this study was to perform analysis of factors which can be consideredresponsible generating road pollution, with resistance to abrasion of gritting sandbeing a potential key problem. The correlation between the use of studded tires andparticulate matter formation has been considered to be one of major issues in urbanareas.In order to carry out this investigation, an individual study case was considered,measurements indicated that levels of pollution increased even after studded tires werebanned.The literature review revealed important knowledge gaps regarding the quantificationof particulate emissions from non-exhaust sources, most importantly, emissions due tolow quality gritting sanding. At this point, very little information is available thatcould be used for determining the resistance to abrasion of gritting sanding material.This is further supported by numerous institutions and companies, all suggesting thatquality of gritting sand is not taken into consideration. Gritting sand is part of abigger problem which also involves types of pavement, types of tires, weather,background pollution, etc. Furthermore, there is no practical method to characterizewear of resistance of gritting sand.
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Winn, Jeremy Paul. "Modeling Large Whale Entanglement Injuries: An Experimental Analysis of the Influence of Tissue Compliance, Line Tension, and Draw-Length on Epidermal Abrasion Resistance." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/WinnJP2006.pdf.
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Silva, Cristina Vitorino da. "Contribuição ao estudo do desgaste superficial por abrasão em concretos empregados em pisos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/32017.
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O desgaste superficial constitui uma das manifestações patológicas mais recorrentes em pisos de concreto. A presença de tal manifestação patológica, proveniente do processo abrasivo, é muito preocupante, uma vez que implica em altos custos para reparar ou substituir este concreto danificado. Portanto, a realização de estudos que buscam avaliar a influência do proporcionamento e tipo de alguns materiais que constituem o traço de concreto, comumente empregado em pisos, é considerada extremamente relevante, no intuito de reduzir a tendência de desgaste dos compósitos. Neste particular, foram avaliados alguns fatores, como o consumo de água (175 l/m³; 190 l/m³; 205 l/m³), o teor de substituição de sílica ativa (0%; 5%; 10%), o teor de adição de microfibras de polipropileno (0 g/m³; 600 g/m³) e o tipo de cimento (CP IV; CP V-ARI). Os ensaios adotados para esta avaliação foram o de resistência à compressão uniaxial, resistência à tração na flexão, dureza superficial por esclerometria, exsudação e resistência à abrasão. Os resultados encontrados mostraram uma influência estatística significativa do tipo de cimento em todas as propriedades avaliadas, sendo que o cimento CP V-ARI apresentou melhor desempenho em comparação ao cimento CP IV, considerando uma mesma relação a/agl (0,53). O fator consumo de água, mantendo-se constante a relação a/agl, mostrou influência significativa na resistência à tração na flexão e na resistência à abrasão dos concretos, e, além disso, foi possível verificar um comportamento semelhante para ambas as propriedades com relação a este parâmetro de controle. Quanto ao teor de substituição de sílica ativa, observa-se que este fator promoveu efeito significativo nas propriedades mecânicas, o que era esperado, na dureza superficial e na exsudação; entretanto, não se verificou influência no desgaste por abrasão dos compósitos cimentícios. Já a adição das microfibras de polipropileno diminuiu significativamente a dureza superficial por esclerometria, sem alterar as demais propriedades analisadas. Os resultados verificados para o desgaste mostraram uma importante relação com as propriedades mecânicas dos concretos. O processo de acabamento como forma de tratamento superficial parece ser efetivo no controle do desgaste por abrasão, uma vez que pode ter minimizado o efeito da exsudação na superfície dos compósitos cimentícios. O consumo de água de 190 l/m³ mostrou ser o teor mais adequado para os materiais e concretos empregados nesta pesquisa.Surface wear is one of the most frequent pathologies in concrete floors. The presence of such pathological manifestation from the abrasive process is very disturbing, since it implies high costs to repair or replace the damaged concrete. Therefore, studies that seek to evaluate the influence of the proportioning and type of some materials that constitute the mixture proportions of concrete, commonly used on floors, are considered extremely relevant, in order to reduce the tendency of surface wear of composites. In this study, factors such as water consumption (175 l/m³, 190 l/m³, 205 l/m³), replacement content of silica fume (0 %, 5 %, 10 %), addition content of polypropylene fibers (0 g/m³, 600 g/m³) and cement type (CP IV; CP V-ARI) were evaluated. The tests used for this assessment were compressive strength, flexural tensile strength, surface hardness by rebound hammer, bleeding and abrasion resistance. The results showed a significant statistic influence of the cement type on all the properties evaluated, with the cement CP V-ARI presenting a better performance compared to cement CP IV, considering the same w/b ratio (0.53). The water consumption factor, maintaining a constant w/b ratio, showed significant influence on the flexural tensile strength and abrasion resistance of concrete, and, in addition, we could observe a similar behavior for both properties with respect to this parameter of control. Regarding the replacement content of silica fume, it is observed that this factor promoted significant effect on the mechanical properties, which was expected, on the surface hardness and bleeding; however, there was no influence on the abrasion of the cementitious composites. The addition of polypropylene microfibers significantly decrease the surface hardness by rebound hammer, without altering any other property evaluated. The results verified for the wear showed an important relationship with the mechanical properties of concrete. The finishing process as a form of surface treatment seems to be effective in controlling the abrasive wear, since it may have minimized the effect of bleeding on the surface of cementitious composites. The water consumption of 190 l/m³ showed to be the most appropriate content for the materials and concrete used in this research.
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Hermansson, Erik, and Ekberg Marcus. "A material study of insoles : Manufactured using different methods." Thesis, Hälsohögskolan, Högskolan i Jönköping, HHJ. Ortopedteknisk plattform, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-44577.
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Aim: The aim of this study is to evaluate if additive manufacturing (AM) is an appropriate manufacturing method for insoles in comparison to vacuum forming (VF) and subtractive manufacturing (SM) in regards of material properties such as abrasion resistance. Background: Traditionally insoles are manufactured with either VF or SM. AM has been around for some decades but implementation into orthotic and prosthetic (O&P) business has not been accomplished yet. Therefore, the quality of the products produced with AM must be tested in comparison with traditional methods. Method: A comparison of samples for the mentioned manufacturing methods was done with the help of an abrasion testing machine with the standard ASTM G133. Two samples were produced from each manufacturing method and respectively tested for one and two hours. All the samples were weighed before and after the tests with the help of a four decimal scale. The difference in weight before and after the test and coefficient of friction was evaluated. The weight difference was analyzed to see how much material had been removed from the sample. The percentage of wear loss was calculated for each specific sample, both for one hour and two hours of testing. No statistical analysis could be made due to the limited amount of samples and testing time. Result: No statistically significant could be found for either wear loss or the coefficient of friction as mentioned above. Conclusion: A conclusion whether which material having the best abrasion resistance for respectively manufacturing method could not be drawn due to limited results. This study can be seen as a pilot study where the methodology can be used in further studies. Further research on AM needs to be conducted.
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Vargas, Isabella Marini. "Reciclagem de vidro laminado: utilização na fabricação de isolantes e vernizes com alta resistência à abrasão para pisos de madeira." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-06072007-143145/.
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Neste trabalho apresenta-se uma alternativa para utilização de vidros laminados provenientes de rejeitos industriais ou pós-consumo. Reciclando o vidro laminado, por meio de uma série de moagens, pode-se obter dois tipos de rejeitos: vidros de partículas pequenas (200 e 325 mesh), que não conseguem ser reaproveitados pela indústria vidreira, e filme de poli(vinil butiral) - PVB - impregnado com uma pequena quantidade de carga, que tem como destino os aterros. No presente estudo, esses dois resíduos foram aproveitados na fabricação de vernizes curados por radiação ultravioleta empregados para proteção de pisos de madeira. O filme de PVB foi utilizado na formulação de um isolante, em razão de sua alta flexibilidade e boa aderência à madeira, e o vidro de baixa granulometria foi empregado como carga nos vernizes chamados de alto tráfego para o aumento da resistência à abrasão dos mesmos (propriedade fundamental de vernizes para pisos de madeira). Pelos resultados obtidos, verificou-se que o isolante preparado com o filme de PVB em solução alcoólica e misturado a um monômero acrílico trifuncional, como o trimetilolpropano triacrilato (TMPTA), quando aplicado sobre pisos de madeira, obteve-se bons resultados de aderência, arrancamento e flexibilidade, podendo assim substituir os isolantes utilizados atualmente, produtos com cura por radiação ultravioleta, em base aquosa, e que apresentam alto custo por serem preparados com resinas importadas. Foi observado que quanto maior a quantidade de solução de PVB, melhor a flexibilidade do filme e, conseqüentemente, melhor a resistência ao arrancamento do revestimento. Os vidros de baixa granulometria apresentaram resultados muito satisfatórios quando utilizados como carga nos vernizes de alto tráfego, especialmente ao se combinarem com o óxido de alumínio (carga atualmente utilizada nesses sistemas), aumentando ainda mais a resistência à abrasão dos vernizes e também a estabilidade dos vernizes (quanto à sedimentação e à geleificação). Para todas as combinações de cargas preparadas neste trabalho foram bons os resultados obtidos, podendo-se optar pela utilização daquelas com maior quantidade de vidro, uma vez que este, por tratar-se de um resíduo, torna tais combinações mais econômicas.The present work features an alternative for the utilization of the windshield after its use. The recycling of the laminated glass, through a series of grindings, make possible to obtain two kinds of materials: glasses of small particles (200 and 325 mesh), that cannot be recovered in the glass industry, and a poly(vinyl butiral) - PVB - sheet impregnated with a small amount of filler, that has as final disposal the sanitary landfill. In this study these two materials were introduced in the formulation of ultraviolet curing varnishes used to the protection of wood flooring. The film of PVB was used in the formulation of a primer, due to its high flexibility and good adherence to the wood, and the glass of low granulometry was used as a filler in the so-called high traffic varnish, to increase the abrasion resistance (main property of these varnishes). The results obtained showed that the primer prepared with the PVB sheet in alcoholic solution, mixed with a trifunctional acrylic monomer, like TMPTA, when applied on wood flooring, obtained good results of adherence, scrape adhesion, flexibility and stability and could substitute the primers used nowadays that are UV curing products, however water based ones, and that has a high cost because of the imported resins that are used in their formulations. It was observed that larger the amount of solution of PVB, better the flexibility of the film and, consequently, better its scrape adhesion. The glasses of low granulometry also presented very satisfactory results when used as fillers in the high traffic varnishes, mainly when in combination with aluminium oxide (filler used in these systems), increasing more the abrasion resistance of the varnishes and also their stability (the sedimentation and geleification have showed better results). To all filler combinations studied in this work the results were good and the best one can be the ones that presented the largest amount of glass, since as a residue, make these combinations more economical.
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Prokopchuk, N. R., Zh S. Shashok, K. V. Vishnevskii, and A. V. Kasperovich. "Properties of Elastomeric Compositions with Highly Dispersed Carbon Additives." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42639.
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The effect of highly dispersed carbon additives (HDCA) obtained in high-voltage discharge plasma on properties of elastomeric compositions is investigated. Some tests to determinate tensile strength, stretching strain, abrasion resistance, hardness and resistance to heat aging of highly filled rubbers based on raw rubber for general and special application are carried out. It is shown that HDCA addition permits to improve
performance characteristics of elastomers based on butadiene-acrylonitrile rubber.
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Ardila, Miguel Angel Narvaez. "Influência da natureza e topografia da superfície na micro-abrasão e micro-abrasão-corrosão." Universidade Federal de Uberlândia, 2017. http://dx.doi.org/10.14393/ufu.te.2018.24.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
O trabalho tem como objetivo contribuir ao entendimento do efeito das caraterísticas superficiais no desgaste abrasivo com e sem efeito corrosivo. Utilizou-se o equipamento de micro-abrasão-corrosão desenvolvido no Laboratório de Tribologia e Materiais (LTM). Foi utilizado nos testes: amostras de aço inoxidável austenítico AISI 304, partículas abrasivas de sílica e velocidade de rotação de 150 rpm. Para a parte corrosiva foi usada solução eletrolítica com 1N de H2SO4. Para a influência da topografia de superfície do corpo de prova o aço AISI 304 foi preparado em lixas de carbeto de silício de granulometria #80 e #4000, e com disposições de lixamento perpendicular e paralelo com respeito ao sentido de rotação da esfera. Esferas de zircônia (Ø 25,4 mm) foram usadas como contra-corpos. Para avaliar a influência da natureza e evolução topográfica da superfície do contra-corpo usaram-se cinco contra-corpos esféricos (Ø 25,4 mm): um cerâmico (nitreto de silício, Si3N4), um metálico (aço AISI 52100) e três polímeros termoplásticos (polipropileno, PP, poliacetal, POM, e poliamida 6,6, PA 6,6); para os testes de micro-abrasão-corrosão foram usados um cerâmico (Si3N4) e um polímero termoplástico (PP). Foi acompanhada a evolução topográfica ao longo dos testes nos contra-corpos por meio de interferometria e perfilometría. O deslizamento das partículas abrasivas foi predominante nas calotas geradas em todos os testes realizados. A topografia de superfície do corpo e contra-corpo mostrou ter relação com a taxa de desgaste na micro-abrasão e micro-abrasão-corrosão. Topografia de superfície com parâmetros de rugosidade maiores apresentam maiores taxas de desgaste, tendo maior sensibilidade na micro-abrasão-corrosão. Atribuiu-se que, com maiores valores dos parâmetros de rugosidade, consegue-se maior efetividade no arraste e participação de partículas abrasivas no contato.
The aim of this work is to contribute to the understanding of the effect of surface characteristics on abrasive wear with and without corrosive effect. The micro-abrasion-corrosion apparatus developed at the Tribology and Materials Laboratory (LTM) was used. The following tests were used: AISI 304 austenitic stainless steel test specimens (body), silica abrasive particles and rotational speed of 150 rpm. For the corrosive analysis, an 1N H2SO4 electrolytic solution was used. For the influence of the surface topography of the specimen, the AISI 304 steel was grinded using silicon carbide (SiC) (#80 and # 4000), and tested with perpendicular and parallel arrangements with respect to the direction of rotation of the sphere. Zirconia balls (Ø 25.4 mm) were used as counter bodies. In order to analyze the influence of the nature and topographic evolution of the counter-body surface, five spherical counter bodies (Ø 25.4 mm) were used in the micro-abrasion tests: one ceramic (silicon nitride, Si3N4), one metal (AISI steel 52100) and three thermoplastic polymers (polypropylene, PP, polyacetal, POM and polyamide 6.6, PA 6.6); For the micro-abrasion-corrosion tests one ceramic (silicon nitride) and one thermoplastic polymer (PP) were used. The topographic evolution of the counter bodies was monitored along the tests through interferometry and profilometry. The grooving of the abrasive particles was predominant in the wear scars generated in all tests performed. The surface topographies of the body and counter-body showed to have relation with the wear rate in the micro-abrasion and micro-abrasion-corrosion tests. Higher roughness parameters induced higher wear rates, and show greater sensitivity in micro-abrasion-corrosion. It was attributed that higher values of the roughness parameters achieved greater effectiveness in the drag and participation of abrasive particles in the contact.
Tese (Doutorado)
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Cao, Yuanmei. "Antireflective Polyimide Based Films." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1335501090.
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García, Hernández Álvaro. "Desarrollo y análisis de pavimentos industriales desde el punto de vista del acabado superficial." Doctoral thesis, Universidad de Cantabria, 2008. http://hdl.handle.net/10803/10710.
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En teoría, el inicio del proceso de flotado de un pavimento de hormigón deberá coincidir con el tiempo de inicio de fraguado. Para resolver este problema, se desarrolló un modelo teórico sobre la evolución de la resistencia a penetración del hormigón antes del inicio de fraguado. Por otra parte, en esta Tesis Doctoral también se ha desarrollado un procedimiento muy sencillo para conocer la energía de activación del hormigón a través de ensayos de Vicat. En esta Tesis se ha hecho también un análisis comparativo de los seis tipos de acabados para pavimentos de hormigón más representativos mediante diferentes tipos de ensayos. Así como un análisis del comportamiento a impacto del pavimento de hormigón. Finalmente, se ha propuesto un modelo para conocer el comportamiento del pavimento sujeto a la abrasión. En él se obtuvo un nuevo modelo estadístico, que puede ser la base de una futura investigación en este campo.Theoretically, the time of troweling a concrete pavement coincides with the setting time. To solve this problem, a theoretical model of the penetration resistance evolution of concrete during the setting time was developed. A new methodology to know the temperature influence on the setting times of concrete and on the time of toweling the pavement has been also performed.Besides, from six experimental pavements with the most representative type of finishing at the time of carrying out the study, a comparative analysis among them was done by means of different types of tests. Moreover, an analysis of the dynamic behavior of the pavement was carried out to know the protective effect of the type of finishing on the slab. Finally, a model for the dynamic behavior of a concrete pavement subjected to abrasion was made.
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Fägerhag, Johanna, and Lisa Magnusson. "Möbeltextil med högluftpermeabilitet : en studie i hur hög luftpermeabilitet kan kombineras med högformstabilitet och nötningshärdighet för textilier." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-14754.
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Luftföroreningar har en negativ inverkan på både miljön och människors hälsa. Pure Air Zone är en tystgående och energisnål luftrenare som är integrerad i en sänggavel vilket skapar en ren luftzon i huvudhöjd hos användaren. I dagsläget är denna sänggavel klädd i ett meshmaterial vilken inte lämpar sig för sovrumsmiljö på grund av dess utseende. Fokus har därför legat på att ta fram en alternativ textil som kan ersätta den nuvarande, utan att funktionen försämras. De viktigaste egenskaperna som textilien behöver uppfylla är hög luftpermeabilitet, hög formstabilitet och hög nötningshärdighet. Tester utfördes med hjälp av en Martindalemaskin, en dragprovare och en permeabilitetsmätare för att mäta dessa egenskaper. Sju stycken vävda tyger från Ludvig Svensson undersöktes för de nämnda egenskaperna och jämfördes mot det nuvarande materialet. Många av de valda tygerna var glest eller tunt vävda vilka stabiliserades genom att de kviltades samman med en filtervadd. Efter genomförda tester viktades de olika egenskaperna för att ge ett sammanställt resultat för samtliga vävar. I sammanställningen visade det sig att det nuvarande materialet fick sämst resultat. För luftpermeabiliteten, den högst prioriterade egenskapen, fick alla utom en väv bättre resultat än referensmaterialet. Den väv som fick bäst resultat efter sammanställningen var en tunn väv i tuskaftbindning som i denna rapport kallas för Day.Air pollution has a negative impact on both the environment and the human health. Pure Air Zone is a silent and energy efficient air purifier which has been integrated in a bed frame. This creates a clean airspace where the user will place its head while sleeping. Currently a mesh material is being used to cover the bed frame but this is not well suited for a bedroom environment when looking at the appearance of the textile. The main focus has therefore been to develop an alternative textile that can replace the current mesh without impairing the function. The most important characteristics the textile has to possess are high air permeability, high dimension stability and high abrasion resistance. Tests were carried out by using a Martindale machine, a tensile tester and a permeability tester to measure these characteristics. Seven woven fabrics from Ludvig Svensson were examined for said characteristics and compared to the mesh which acted as a reference material. Majority of the chosen weaves were thinly or sparsely woven and had to be stabilized by quilting them together with filter wadding. After completed tests the characteristics were weighed against each other to present a combined result for all the weaves. In the combined results it was clear that the current mesh material being used for the bed frame got the overall lowest result. For air permeability, the highest weighed characteristic, all but one weave got a better result than the reference material. The weave that got the best combined result was a thin plain weave that will be referred to as Day in this report.
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Silva, Wanderson Santana da. "Avaliação do comportamento mecânico e tribológico de ligas Ni-Cr-Al-C." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-20042007-173509/.
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Este trabalho traz contribuições à linha de pesquisa \'Nova Família de Ligas Baseada no Sistema Ni-Al-Cr-C Resistentes ao Desgaste em Elevadas Temperaturas\', estudando o comportamento mecânico, tribológico e a estabilidade superficial destas ligas. Esta família de ligas fundidas, denominada NICRALC - busca conjugar algumas características das superligas à base de níquel e dos ferros fundidos brancos, aliando ao comportamento mecânico anômalo do Ni3Al - aumento da resistência mecânica com a temperatura, até valores da ordem de 800°C - a uma dispersão de carbonetos de cromo de alta dureza. Desta forma, busca-se desenvolver uma alternativa às ligas ferrosas nas temperaturas acima das quais estas ligas perdem significativamente sua resistência mecânica (notadamente 600 °C), assim como uma alternativa mais econômica às ligas a base de cobalto resistentes ao desgaste, em virtude das altas cotações e instabilidades no preço deste elemento. Neste trabalho foram avaliadas as propriedades mecânicas em elevadas temperaturas (compressão e dureza), tenacidade à fratura na temperatura ambiente, comportamento tribológico (cavitação, abrasão, deslizamento e erosão) e a resistência à oxidação ao ar e à carburação em atmosfera redutora, em temperaturas elevadas, de ligas Ni-Al-Cr-C (NICRALC) fundidas. Ligas NICRALC fundidas com diferentes teores de carbono e submetidas a diferentes tratamentos tiveram seu comportamento mecânico e tribológico comparado ao comportamento do STELLITE 6 fundido, a uma liga NICRALC produzida por deposição por \'SPRAY\', a um ferro fundido branco alto cromo fundido convencionalmente e a um ferro fundido branco alto cromo depositado por \'SPRAY\'. Os ensaios de compressão confirmaram o comportamento anômalo da matriz ordenada Ni3Al. As ligas NICRALC apresentaram aumento ou manutenção da resistência ao escoamento com o aumento da temperatura de ensaio. A mesma tendência foi encontrada nos ensaios de dureza a quente. As demais ligas apresentaram tendência de queda da resistência ao escoamento e da dureza com o aumento da temperatura de ensaio. Esta tendência é mais acentuada na liga STELLITE, desta forma, as ligas NICRALC apresentaram em altas temperaturas maior resistência ao escoamento e maior dureza que o STELLITE. Os diferentes ensaios de desgaste mostraram, em geral, uma maior resistência do STELLITE em comparação com as ligas NICRALC na temperatura ambiente. Nestas condições verifica-se que a menor resistência mecânica da matriz ordenada nas ligas NICRALC é determinante para definir uma menor resistência ao desgaste na temperatura ambiente. Nos ensaios de erosão-oxidativa realizados a 600 e 800°C as ligas NICRALC mostraram perdas de massa menores que as experimentadas pelo STELLITE e pelos ferros fundidos. As ligas NICRALC com microestrutura de carbonetos mais homogênea, próxima do eutético, mostraram melhor comportamento sob desgaste abrasivo e erosivo se comparadas às ligas NICRALC 05 e 13. Os ensaios de resistência à oxidação mostraram que as ligas NICRALC são mais resistentes à oxidação que o STELLITE. Além disso, observou-se grande propensão ao destacamento dos filmes de óxidos formados nos STELLITES em temperaturas acima de 800°C. Os ensaios de resistência à carburação mostraram que no caso das ligas NICRALC ocorreu a precipitação de um depósito de grafita e, subjacente a esta, a formação de uma zona de fragmentação microestrutural, na qual se observa empobrecimento ora do Al ora do Cr, que aparentemente impede o avanço do processo. No caso do STELLITE verificou-se a ocorrência do aumento da fração volumétrica de carbonetos, típico dos casos clássicos de carburação. Os procedimentos de simulação termodinâmica utilizados indicam a necessidade de se implementar a descrição da solubilidade do carbono na fase ordenada de forma a permitir o pleno uso do software THERMOCALC no projeto e aprimoramento de ligas NICRALC.This work contributes to the research line \'New Family of High Temperature Wear Resistant Alloys based on the Ni-Al-Cr-C System\', studying the mechanical and tribological behaviour and the surface stability of these alloys. This family of foundry alloys, called NICRALC, tries to unite some of the characteristics of the Ni based superalloys and the high-chromium-white-cast-irons, associating the anomalous behaviour of the ordered intermetallic phase Ni3Al - which increases its strength with the increase of temperature - with a dispersion of hard chromium carbides. The aim is to develop an alternative to iron-based wear resistant alloys at temperatures where they loose significantly their strength, as well as substituting cobalt based high temperature wear resistant alloys, which suffer from the instability and high cost of the Co metal. The high temperature mechanical properties (hardness and compression), room temperature fracture toughness, tribological behaviour (cavitation, abrasion, sliding and erosion) and resistance to high temperature oxidation and carburization of cast Ni-Al-Cr-C (NICRALC) alloys are studied. Cast NICRALC alloys with different C contents and different heat treatments were compared with a cast STELLITE 6, a conventionally cast high chromium white cast iron, a spray formed high chromium white cast iron and a spray formed NICRALC. Mechanical tests in compression confirmed that NICRALC alloys share the anomalous behaviour of the ordered intermetallic phase Ni3Al, increasing or maintaining their yield strength with increased testing temperature. The same occurred with hot hardness tests. STELLITE and all other alloys showed loss of strength with increased testing temperatures. Thus NICRALC alloys showed higher strength and hardness than STELLITE at high temperatures. All wear tests showed a higher wear resistance of STELLITE in comparison with NICRALC at room temperature. This result can be explained by the higher matrix hardness of STELLITE at room temperature. Oxidative-erosion tests run at 600 and 800° C showed that NICRALC suffered smaller mass loss than STELLITE and the white cast irons. NICRALC alloys with more homogeneous carbide distributions (eutectic alloys) obtained the best results under severe oxidation-erosion conditions. NICRALC alloys were more oxidation resistant than STELLITE alloy, which tended to break and detach the oxide layer formed above 800°C under air. During carburization essays in a reducing atmosphere the NICRALC alloys tended to form a coke-like graphite layer, over a layer with a fragmented microstructure depleted alternatively in chromium and aluminum, which effectively stopped the advance of the process. The STELLITE alloy suffered an increase in carbide volume fraction, a classic carburizing behaviour. The thermodynamic simulation results show that it is still needed to introduce the solubility of carbon on the ordered Ni3Al phase in the model in order to be able to fully calculate the NICRALC phase diagrams.
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Václavík, Ondřej. "Studium otěruvzdorných vrstev vytvořených laserovým naplavováním pomocí metody dynamického rázového impaktoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230536.
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Diploma thesis studies the layers created by laser cladding and method of testing abrasion resistance of these layers using the method of dynamic shock impactor. In the theoretical part describes laser technologies and their applications, hardness testing and methods of testing of coatings. Proposed by the mechanical testing of the selected materials were carried out and evaluated in the experimental part. The conclusion summarizes final results of the experiment.
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Rebmann, Markus Samuel. "Durabilidade de concretos estruturais com baixo consumo de cimento Portland e alta resistência." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-10062011-150726/.
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Este trabalho apresenta um estudo sobre a confecção de concretos estruturais com baixo consumo de cimento Portland e avalia algumas das suas propriedades no estado fresco e endurecido, tanto em termos mecânicos como de durabilidade. O uso de concretos de baixo consumo de cimento Portland tem por objetivo possibilitar maior sustentabilidade da indústria da construção baseada no concreto, como maior longevidade de jazidas, reduções na emissão de \'CO IND.2\' e no consumo de energia e menores custos de transporte. Possibilita também diversas melhorias técnicas, como menor retração, fissuração e calor de hidratação. Com base em conceitos de empacotamento e dispersão de partículas, uso de adições minerais e fílers e escolha adequada dos materiais, obtiveram-se concretos com baixo consumo de cimento e alta resistência, com consumo relativo de materiais aglomerantes inferior a 5 kg/\'M POT.3\' para produzir 1 MPa de resistência à compressão. Avaliaram-se diversos parâmetros relacionados à durabilidade destes concretos com base em ensaios de absorção de água por imersão, absorção de água por capilaridade, permeabilidade, abrasão, carbonatação e potencial de corrosão. Os resultados obtidos indicam que os concretos de baixo consumo de cimento obtidos podem ter durabilidade comparável ou até superior a concretos usualmente considerados como de bom desempenho. Observou-se que a durabilidade é dependente do tipo de cimento empregado e que deve ser avaliada especificamente com relação ao tipo de ação agressiva a que o concreto estará exposto.This dissertation presents a study on the development of structural concrete with low Portland cement consumption and evaluates some of its fresh and hardened properties, in mechanical and durability terms. The use of low concrete Portland cement consumption is intended to enable greater sustainability of the construction industry based on concrete, as increased longevity of deposits, reductions in \'CO IND.2\' emissions and energy consumption and lower transportation costs. It also allows several technical improvements, such as reduced shrinkage, cracking and hydration heat. Based on particle packaging and dispersion, use of mineral additives and fillers and appropriate choice of material, concrete with low cement content and high strength was obtained, with relative consumption of binder materials below 5 kg/\'M POT.3\' to produce 1 MPa compressive strength. Various durability parameters were evaluated based on tests such water absorption by immersion, water absorption by capillarity, permeability, abrasion, corrosion potential and carbonation. The results indicate that the low cement consumption concretes may have achieved comparable or superior durability to concrete usually regarded as good performance. It was observed that the durability is dependent on the type of cement used and that durability should be assessed specifically with regard to the type of aggressive action that the concrete will be exposed.
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Scholl, Milton R. "Development of intermetallic-hardened abrasion-resistant weld hardfacing alloys /." Full text open access at:, 1986. http://content.ohsu.edu/u?/etd,95.
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Chinyamakobvu, Oswald Simbarashe. "Metal matrix composites for abrasive wear resistance." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/46998.
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Li, Chenghong. "Inorganic-Organic Sol-Gel Derived Hybrid Materials as Abrasion Resistant Coatings." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/39013.
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Inorganic-organic hybrid materials have been developed using sol-gel reactions of a trialkoxysilylated organic compound and a metal or semi-metal alkoxide and applied as coatings on polymeric or metallic substrates. Many of these coatings have demonstrated good to excellent abrasion resistance.
Abrasion resistant coatings were prepared by hydrolysis and condensation of mixtures of a triethoxysilylated diethylenetriamine (f-DETA), tetramethoxysilane (TMOS), water and an alcohol in the presence of an acid catalyst (a one-step hydrolysis approach). The influences of many formulation and processing variables on the gelation time, optical properties, hardness and abrasion resistance were investigated. An aminolysis mechanism was also proposed to explain the adhesion between sol-gel derived coatings and polycarbonate substrates promoted by a 3-aminopropyltriethoxysilane (3-APS) primer. FT-IR, GPC, 1H and 13C NMR, XPS experiments were conducted to support this mechanism.
The f-DETA/TMOS system is essentially a binary system of an alkyltriethoxysilane (T) and a tetraalkoxysilane (Q). At pH 0-2 and pH 4-5, the relative condensation reactivities of the T and Q species in this system were compared using 29Si NMR spectroscopy. After thermal curing, 13C or 29Si solid state NMR spectroscopy was used to estimate the extent of hydrolysis of the urea linkages in f-DETA, the concentration of residual alkoxysilane groups, and the extent of condensation for both T and Q species. The dependence of the morphology of f-DETA/TMOS gels on the pH and the water concentration was also investigated using AFM, SEM and SAXS.
Many other trialkoxysilylated organic compounds containing urea, urethane, epoxy and siloxane linkages were also synthesized and utilized to prepare abrasion resistant coatings via a one-step hydrolysis approach, a two-step hydrolysis approach or a moisture-curing approach. Coatings derived from many of these systems or approaches demonstrated abrasion resistance comparable to that of the f-DETA/TMOS coating. Thin coatings were also derived from cubic octasilicate monomers via hydrosilylation or sol-gel reactions. These coatings were very transparent but unfortunately lacked abrasion resistance.Ph. D.
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Brandt, Jennifer M. "Rheological and abrasion resistant properties of transparent polymer/silicate nanocomposite coatings." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010040.
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Shepperson, S. V. "The abrasive wear resistance of austempered spheroidal graphite irons." Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/17647.
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Bibliography: pages 103-107.A study has been made of the structure and abrasive wear resistance of two austempered commercial spheroidal cast irons. Heat treatments have been carried out for different times between 2 and 120 minutes for a range of austenitising temperatures between 850°C and 950°C and austempering temperatures between 250°C and 450°C. The morphology and constitution of the resulting dual phase ferrite/austenite structure has been examined using optical and scanning electron microscopy and x-ray analysis. The maximum quantity of retained austenite in the structure has been shown to vary up to 50% and to be strongly dependent on heat treatment parameters and the composition of the iron. Laboratory abrasive wear testing has been carried out on these austempered irons and compared with the results of similar tests on a range of abrasion resistant carbon steels. All the austempered irons were found to have better abrasion resistance than proprietary abrasion resistant steels. These austempered irons derive their outstanding properties from the morphology of the dual phase ferritic/austenitic matrix coupled to the high work hardening characteristics brought about by the stress induced austenite to martensite transformation during abrasion. The influence of microstructure and mechanically induced transformation has been studied as a function of austempering temperature and time.
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Jordens, Kurt. "Hybrid Inorganic-Organic Materials: Novel Poly(Propylene Oxide) Based Ceramers, Abrasion Resistant Sol-Gel Coatings for Metals, and Epoxy-Clay Nanocomposites. With an Additional Chapter On: Metallocene Catalyzed Linear Polyethylene." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/30194.
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The sol-gel process has been employed to generate hybrid inorganic-organic network materials. Unique ceramers were prepared based on an alkoxysilane functionalized soft organic oligomer, poly(propylene oxide) (PPO), and tetramethoxysilane (TMOS). Despite the formation of covalent bonds between the inorganic and organic constituents, the resulting network materials were phase separated, composed of a silicate rich phase embedded in a matrix of the organic oligomer chains. The behavior of such materials was similar to elastomers containing a reinforcing filler. The study focused on the influence of initial oligomer molecular weight, functionality, and tetramethoxysilane, water, and acid catalyst content on the final structure, mechanical and thermal properties. The sol-gel approach has also been exploited to generate thin, transparent, abrasion resistant coatings for metal substrates. These systems were based on alkoxysilane functionazized diethylenetriamine (DETA) with TMOS, which generated hybrid networks with very high crosslink densities. These materials were applied with great success as abrasion resistant coatings to aluminum, copper, brass, and stainless steel. In another study, intercalated polymer-clay nanocomposites were prepared based on various epoxy networks montmorillonite clay. This work explored the influence of incorporated clay on the adhesive properties of the epoxies. The lap shear strength decreased with increasing clay content. This was due to a reduction in the toughness of the epoxy. Also, the delaminated (or exfoliated) nanocomposite structure could not be generated. Instead, all nanocomposite systems possessed an intercalated structure.
The final project involved the characterization of a series of metallocene catalyzed linear polyethylenes, produced at Phillips Petroleum. Polyolefins synthesized with such new catalyst systems are becoming widely available. The influence of molecular weight and thermal treatment on the mechanical, rheological, and thermal behavior was probed. Although the behavior of this series of metallocene polyethylenes was not unlike that of traditionally catalyzed materials, this work is one of the first comprehensive studies of these new linear polyethylenes. The main distinction between the metallocene and traditional Ziegler-Natta catalyzed polyethylenes is the narrow molecular weight distributions produced by the former (for this series of materials, 2.3< Mw  Mn <3.6).Ph. D.
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Vihar, Boštjan [Verfasser], Peter [Akademischer Betreuer] Bräunig, and Werner [Akademischer Betreuer] Baumgartner. "Mimicking the abrasion resistant sandfish epidermis / Boštjan Vihar ; Peter Bräunig, Werner Baumgartner." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1128157004/34.
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Gutman, Lucie. "Selection of high-temperature abrasion resistant steels for the mining and processing industry." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80967.
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High-temperature abrasion is an expensive issue in industrial fields such as glass and cement production or mining and processing industry. Yet its effects on steel are not well documented. This study investigates and analyses the behaviour of six different steel grades placed in hot abrasive conditions similar conditions encountered in the industry to enables better material selection. Abrasion tests in a slurry pot were done at room temperature and at 500 °C. Impact and tensile tests were also performed at different temperatures. To complete the mechanical properties evaluation, hardness measurements were executed before and after tempering at 500 °C. Wear rates assessed at room temperature or at 500 °C, are independent of the mechanical properties of the material. At high temperature, it was shown that wear rates and performance of the steels were influenced by tempering and leading to a unique microstructures for all steel grades investigated and equalize their performances. To conclude, high temperature wear of the investigated grades does not depend on their mechanical properties, however, it can be influenced by their tempering resistance. As the temperature increase, steel tempers, its mechanical properties decrease and homogenise with other steel grades' performances, but some grades keep their properties longer at high temperature.
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Betrabet, Chinmay Suresh. "Inorganic-organic hybrid materials and abrasion resistant coatings based on a sol-gel approach." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40188.
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Novel inorganic-organic hybrid materials made previously in the laboratory have
utilized acids catalysts such as HCI, acetic acid, toluene sulfonic acid and polystyrene sulfonic acid to catalyze the sol-gel reaction. The sol-gel reaction can also be catalyzed under near neutral (i.e. 5 < pH < 7) and basic conditions. The effects of synthesizing hybrid materials under near basic and basic conditions has not been studied.
Attempts to synthesize hybrid materials from polytetramethylene oxide (PTMO) end functionalized with triethoxy silyl groups and, tetraethylorthosilicate (TEOS) under basic conditions met with only partial success. The films obtained had low mechanical stability. This was attributed to the low reactivity of the triethoxy species under neutral and basic conditions. In contrast, films with good mechanical stability were obtained when the TEOS was replaced with titanium tetraisopropoxide (TIOPR). The microstructure of the TIOPRlPTMO hybrid synthesized under near neutral conditions was generally similar to the acid catalyzed PTMOffIOPR hybrids.Ph. D.
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Santos, Fellipe Cros dos. "Avaliação da influência do teor de cromo e do tratamento térmico de desestabilização da austenita na dureza e resistência ao desgaste abrasivo de ferros fundidos brancos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/178408.
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As ligas de ferro fundido branco alto cromo (FFBAC) da norma ASTM A-532 são comumente utilizadas em peças que necessitam de elevada resistência ao desgaste. Tal escolha acontece devido à elevada dureza apresentada por tais materiais, o que propicia maior vida útil dos componentes. Entretanto, uma vez que o teor de cromo utilizado nos FFBAC possui grande influência no custo das peças, é importante garantir que os tratamentos térmicos (TOTO’s) aplicados estejam otimizados para cada composição de liga. Buscando atuar nesse sentido, esta dissertação analisou a utilização de diferentes tempos e temperaturas de patamar em TOTO’s de desestabilização da austenita para duas ligas da norma ASTM A-532 (ligas com 20% e 25%Cr). Após tais procedimentos, foram estudadas a dureza e a resistência ao desgaste, tanto para algumas das amostras tratadas quanto para seis amostras de FFBAC fornecidas por diversas fundições nacionais. Os resultados demonstraram a existência de uma temperatura que otimiza a dureza da liga, possibilitando incrementos desta propriedade nas amostras tratadas em valores de até 37% (considerando a dureza inicial na condição “bruto de fusão”). Com relação ao tempo de patamar, verificou-se que o mesmo apresentou pouca influência no incremento de dureza, apresentando variações máximas inferiores à 4% para tratamentos variando entre 30 minutos à 6 horas de duração, resultado que destoou daquele indicado pela literatura. Além disso, verificou-se que uma liga com 19,6 %Cr pode apresentar uma dureza até 11% maior do que o verificado para ligas comerciais Nesta comparação, apesar da liga comercial possuir menor teor de carbono, ficou evidenciado o indicativo de que as peças consideradas neste estudo e oriundas de fundições nacionais não otimizam os resultados de seus TOTO’s. A resistência ao desgaste, por sua vez, demonstrou não depender apenas da macrodureza das amostras, mas também de outras características como tamanho, distância e continuidade dos carbonetos primários, o que explica a obtenção de resultados similares de perda de massa no ensaio abrasivo para amostras que possuem durezas diferindo em cerca de 12% porém possuindo tamanho de microconstituintes similares. Por fim, observou-se que ligas com maiores teores de cromo e menores teores de carbono apresentam menores valores de dureza e resistência ao desgaste, o que viabiliza uma aplicação com maior vida útil e menor custo.The high chromium white cast iron alloys from ASTM A-532 are commonly used in parts which wear resistance are required. This choice happens due the great hardness showed by these alloys, what propitiates a higher lifetime for the components. However, since chromium content has great influence in the cost of the parts, it is important ensure that the apply heat treatments are optimized for each alloy composition. Thus this dissertation analyzed the application of different heat treatment cycles on the austenite destabilization for two ASTM A-532 alloys (20%Cr and 25%Cr). After the heat treatment, hardness, wear resistance and microstructure were analyzed, both for some of the treated samples as for six samples provided by different manufactures in Brazil. The results showed the existence of a temperature that optimizes the alloy hardness, allowing increases on this property in values up to 37% (considering the initial hardness of the “as cast” condition) Concerning the time of heat treatment, was verified that this parameter has low influence in the increase on hardness, showing maximum variations lower than 4% in treatments with times coming from thirty minutes until six hours, results that does not match that one’s indicated by the literature. Besides that, it was verified that an alloy with 19,6%Cr can present a hardness 11% greater than that verified in commercial. In this comparation, although the commercial alloy having lower carbon content, was evidenced that the parts from the Brazilians companies which were considered in this study, does not have an optimum heat treatment. The wear resistance was not only depend of the sample hardness, but also of other characteristics as size, distance and continuity of the primary carbides, which explain the results of similar mass loss in the abrasive test for samples with hardness differing about 12%, but with similar size of microconstituents. Finally, it was observed that alloys with higher chromium and low carbon content shows lower hardness and wear resistance values than alloys with low percentages of chromium, what enable an application with larger lifetime and lower cost.
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Barker, Keith Cecil. "The development of abrasive-corrosive wear resistance of steels by microstructural control." Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/22508.
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Bibliography: pages 212-223.The performance of developmental alloyed steels with improved abrasive-corrosive wear resistant properties has been evaluated. The synergistic effect of abrasion and corrosion in the accelerated wear of steels is examined and the main parameters identified. A model of the process is proposed. The model is used to develop the optimum abrasive-corrosive wear resistance in steels for applications in the gold mines of South Africa. A wide range of engineering steels, both commercially available and experimental, has been evaluated in laboratory simulated abrasive and abrasive-corrosive wear tests. An appraisal of the wear tests and the applicability of the results to in-service conditions has led to the development of an additional abrasive-corrosive wear test. It has been established that both the microstructure and chemical composition determine the resistance of a material to wear. Control of the microstructure by alloying and heat treatment is attempted in order to optimise the abrasive-corrosive wear resistant properties for each class of microstructure whilst maintaining adequate formability and weldability. Abrasion of a metal surface has been shown to accelerate the rate of corrosion. Three categories of corrosion behavior are defined. A model of the abrasive-corrosive wear process is proposed to account for the behavior. The model adequately predicts the outcome to a change in system parameter, namely: an increase in the corrosivity of the water, an increase in the frequency of abrasive events, a change in the chemical composition and the degree of passivity inherent in the material. Recommendations are made to maximize the abrasive-corrosive wear resistant properties without resorting to expensive highly alloyed steels. To satisfy the needs of the mining industry, two microstructures of note are identified: a metastable austenitic (TRIP type) steel and a 0.25% carbon lath martensitic alloyed steel. A basic chemical composition is proposed with each microstructure. The austenitic steel is shown to achieve its abrasion resistance through the high degree of work hardening it undergoes during abrasion and the high ultimate strength of the strained material. The lath martensitic steel has the necessary strength to toughness ratio for good abrasion resistance. A 20% degree of work hardening in conjunction with a bulk hardness in excess of 500 HV is prescribed for superior abrasion resistant properties in the wear system of the mines. The life time cost of the martensitic alloyed steel recommends it for applications in the gold mines of South Africa.