Tesis: "Abrasive material"

1

Wang, Aiguo. "Abrasive wear of metal matrix composites". Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305516.

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Mouritz, Adrian Paul. "The abrasive wear of rock drill bit materials". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315846.

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3

Kurd, Michael Omar 1982. "The material and energy flow through the abrasive waterjet machining and recycling processes". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32766.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 109-111).
The purpose of this thesis was to investigate the material and energy flow through the abrasive waterjet machine and the WARD recycling machine. The goal was to track all of the material, water, abrasive, energy, air, and tooling through the different components of the machining and recycling processes. The material removal was found to be a function of length and part geometry, while all of the other variables were simply a function of time. The cutting speed determines the abrasive use, water use, and power use, and is varied based on the material, geometry, thickness and cut quality. The cutting speed was found to be linear with machineability--a measure of the material, almost linear with hardness--inversely related to thickness, somewhat inversely related to quality, and linear with power. Water was found to be the most abundant consumable, following by abrasive, together making up over 99% of the output waste. In the recycling process, roughly 60% of abrasive can be recycled after a single use, with the only significant consumable being power, used to dry the moist abrasive. Replacement tooling on both the abrasive waterjet and the WARD recycling unit were found to be negligible compared to the large amount of abrasive sludge produced every minute.
by Michael Omar Kurd.
S.B.

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4

Abbatelli, Daniele. "Material flows in the waterjet industry : an environmental perspective". Thesis, Linköpings universitet, Industriell miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111003.

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Abrasive Waterjet cutting (AWJ) presents many advantages over competing machining techniques, but several issues are related to the high volume of materials (and in particular of abrasive) used in the process. In this study, the environmental impact of the material flows in the abrasive waterjet industry has been analyzed adopting a life cycle perspective in order to individuate which phases place the largest burden on the environment. Moreover, three alternative abrasives (crushed rock, recycled glass and synthetic abrasive) and three disposal practices (in-site recycling, off-site recycling and recycling as construction material) have been also evaluated to estimate the benefits that can be achieved if these could be used in place of garnet abrasives and landfilling. The transportation of the abrasive resulted to be the phase that has the largest influence in every case and thus should be reduced as much as possible. For what concerns the alternative options, the usage of recycled glass and the in-site recycling of the abrasive were the two alternatives with the best environmental performances. However, crushed rock could be the best option for what concerns the global warming potential if carbon sequestration due to carbonation of silicate rocks is taken into account. Off-site recycling and recycling as construction material are good options only if the transportation to the recycling site can be reduced. Synthetic abrasive are instead found to have a much larger impact compared to every other alternative examined.

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5

Kordowska, Marta. "Analysis of material displacement in the micro- and nanocutting zone with diamond abrasive grain : doctoral dissertation". Rozprawa doktorska, [s.n.], 2021. http://dlibra.tu.koszalin.pl/Content/1424.

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6

Lauand, Valena Hennies. "Gravação de materiais de engenharia com jato d\'água abrasivo". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-11082010-163033/.

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O presente trabalho descreve a utilização do jato d\'água abrasivo como ferramenta de gravação em ladrilhos de Mármore Branco de Cachoeiro de Itapemirim e em placas de vidro plano comum. São apresentadas as variações de desempenho do processo de gravação, assim como as várias geometrias de ranhuras obtidas com a variação de diversos parâmetros do equipamento. Os resultados da gravação em diversas amostras foram digitalizadas e fotografadas. Além disso apresenta o resultado da gravação, em mármore e vidro de um desenho de geometria complexa. Finalmente discussões e conclusões a respeito dos resultados obtidos são apresentadas.
The current thesis describes the use of abrasive water jet as an etching tool in Branco de Cachoeiro de Itapemirim Marble plate and in float glass plate. Etching process performance variations are introduced as well as different kerf geometries obtained with variation of many processes parameters. The results of the etching in several samples have been photographed and scanned. Furthermore the results of the etching of a complex drawing in marble and glass is shown. Finally conclusions and discussions over the achieved results are described.

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7

Bianchi, Eduardo Carlos. "Estudo do comportamento de discos abrasivos, em operações do tipo "Cut-off" por mergulho basculante, submetidos à diversas condições de corte sem lubrificação /". Bauru : [s.n.], 1997. http://hdl.handle.net/11449/116081.

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Resumo: O corte de aços por disco abrasivo é um dos processos que apresentam as melhores características de economia, eficiência e rapidez, e ainda hoje é muito utilizado no meio industrial se comparado a outros processos tradicionais de corte como o cisalhamento (tesourão), torneamento (sangramento), serragem com serras metálicas, serragem por atrito com lâminas circulares sem dentes e chama oxi-acetileno. Da literatura formal mais recente, nota-se que durante os últimos anos as máquinas para a realização dos cortes foram inovadas. Entretanto, esta atenção não foi dada à ferramenta de corte abrasiva. A falta de literatura técnica dificulta a escolha das condições de corte e da sua otimização no meio industrial. Este fato é agravado pela grande diversidade de discos abrasivos disponíveis no mercado, com diferentes qualidades e preço. As decisões sobre as condições de corte são baseadas em experiências pessoais, sem critério definido, e freqüentemente desprezam os aspectos de segurança inerentes ao processo. A concorrência estrangeira, através da globalização da economia, está obrigando as indústrias nacionais a atenderem os padrões internacionais de qualidade e desempenho. Uma forma das indústrias nacionais tornarem-se mais competitivas é através do conhecimento detalhado das operações de corte com discos abrasivos. Neste trabalho é apresentado um estudo sobre o comportamento de discos abrasivos, submetidos a diversas condições de corte. Os resultados são discutidos em função da análise da velocidade de corte, velocidade de mergulho do disco abrasivo na peça, força tangencial de corte média, tempo de corte e relação G.
Abstract: The cut-off operation shows the best savings, efficiency and quickness caracteristics and nowadays it is very used in the industrial environments if compared to other traditional cutting operations like shearing, turning, sawing with metalic hacksaws, friction sawing with non-tooth circular blades and oxi-acetylene torch cutting. In the most recent bibliography, it is noted that the new cutting machines have been improved. However, this fact did not happen in the abrasive cut-off tools. The lack of technical bibliography led the cutting conditions and optimizations choices to be a hard action. Such difficulties are worsen because there are many kinds of abrasive cutting wheels available with different qualities and prices. So, these choices are based on personal experiences, without parameters, and frequently despise the security aspects of the operations. The foreign competition, through the economy globalization, is forcing the national industry to attend the international quality and performance standards. One way for the national industries become more competitives (improving the productivity and decreasing the production costs) it is by the detailed knowledgment of the cut-off operations with abrasive wheels. This work shows a research about the abrasive wheels behavior, under several cutting conditions. The results are discussed in function of the cutting speed, downfeed of the abrasive wheel, average of tangencial cutting force, time per cut and G parameter analysis.

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8

Jankovský, Július. "Náhrada křemičitého plniva v opravných maltách umělým hutným materiálem". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216562.

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Master‘s thesis “Substitution of silica filler in the repair mortars by artifical compact material“ could by generally divided into two parts theoretical and experimental. The theoretical part is mainly focused on summarizing knowledge about repair mortars. The repair mortars are used for reprofilation of disrupted concrete layers, and therefore some of the most common defects of these layers, from which we can determine requirements for repair mortars are listed in the thesis. In the theoretical part, there is also mentioned a general formula of how to prepare a repair mortar, also there are described manufacture and characteristics of the most important ingredients of mortars such as cement, filler (aggregate), water and chemical modificators. Above all the theoretical part is focused on the effects that individual ingredients have on the resulting properties of repair mortars. The experimental part could be further divided into two parts. In the first part there are listed properties of the individual investigated materials and also there is introduced theoretical basis for particular tests of properties of repair mortars, such as analysis of grading distribution of a filler (aggragate), tests of flexular and compression strengths and frost resistance. In the first part there are also proposed formulae of mortar mixtures, where part of the original filler was substituted by an abrasive material TRYMAT, artificial compact aggregate made from blast furnace slag UHK d/D, or their combination. The properties of these mortar mixtures were compared to referential mortar mixture PANBEX R1. In the second part of experimental section is dedicated to summarization and discussion of the obtained results for individual mortar mixtures.

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9

Brym, Radek. "Trendy vývoje obrábění vodním paprskem". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228165.

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In diploma thesis there is elaborated the analysis of assumed development of water jet technology and there is analyzed the level of water jet method in production. There are introduced the possibilities of new applications of water jet machining and the possibilities of it’s future development. There is think over the enlargement of this method in next 5 years. Simultaneously there is solved the question of techno economic operation severity of this technology.

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10

Mareš, Pavel. "Souvislost vad řezu s řeznými parametry při řezání abrazivním vodním paprskem". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230789.

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The aim of this thesis is to determine the area where there is no random step change in cutting edge roughness. This area is established on the basic of samples created by the abrasive water jet cutting method with variation of technologic parameters.

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11

Маценко, І. М. "Розрахункове та експериментальне дослідження технологічних параметрів ежекторно-очисної установки з метою підвищення її ефективності". Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/82290.

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У даній роботі проводилося дослідження ежекторно-очисної установки з метою виявлення можливих шляхів по підвищенню ефективності оброблення деталей. В якості ежектора використовується піскоструменеве сопло, від ефективності якого залежить ефективність всієї піскоструменевої установки. У робочому соплі змішуються два потоки: абразивного матеріалу та повітря. Течія абразивної суміші, що проходить через сопло, в даній роботі досліджувалася чисельно та експериментально.
В данной работе проводилось исследование эжекторно-очистной установки с целью выявления возможных путей по повышению эффективности обработки деталей. В качестве эжектора используется пескоструйная сопло, от эффективности которого зависит эффективность всей пескоструйной установки. В рабочем сопле смешивается два потока: абразивного материала и воздуха. Течение абразивной смеси, проходящей через сопло, в данной работе исследовалось численно и экспериментально.
In this work, an ejector-cleaning plant was carried out in order to identify possible ways to improve the efficiency of machining parts. A sandblasting nozzle is used as an ejector, the efficiency of which determines the efficiency of the entire sandblasting unit. Two streams are mixed in the working nozzle: abrasive material and air. The flow of the abrasive mixture passing through the nozzle in this work was studied numerically and experimentally.

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12

Мірошніченко, М. О. "Підвищення ефективності технології струменево-абразивного оброблення". Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/82291.

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У даній роботі проводилося дослідження ежекторно-очисної установки з метою виявлення можливих шляхів по підвищенню ефективності оброблення деталей. В якості ежектора використовується піскоструменеве сопло, від ефективності якого залежить ефективність всієї піскоструменевої установки. У робочому соплі змішуються два потоки: абразивного матеріалу та повітря. Течія абразивної суміші, що проходить через сопло, в даній роботі досліджувалася чисельно та експериментально.
В данной работе проводилось исследование эжекторно-очистной установки с целью выявления возможных путей по повышению эффективности обработки деталей. В качестве эжектора используется пескоструйная сопло, от эффективности которого зависит эффективность всей пескоструйной установки. В рабочем сопле смешивается два потока: абразивного материала и воздуха. Течение абразивной смеси, проходящей через сопло, в данной работе исследовалось численно и экспериментально.
In this work, an ejector-cleaning plant was carried out in order to identify possible ways to improve the efficiency of machining parts. A sandblasting nozzle is used as an ejector, the efficiency of which determines the efficiency of the entire sandblasting unit. Two streams are mixed in the working nozzle: abrasive material and air. The flow of the abrasive mixture passing through the nozzle in this work was studied numerically and experimentally.

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13

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

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14

Svensson, Erik y Marcus Wiechert. "Abrasiv nötning av polymerer tillverkade genom 3D-skrivning". Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-11124.

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Volvo Cars in Skövde manufacture and assemble Volvo engines. When attaching the ignition coil to all 4-cylinder engines, a special mounting tool is required. This mounting tool is currently manufactured from injection-molded polyoxymethylene (POM), a thermoplastic. It has been noted that the life span of the tool is shortened as a result of abrasive wear that occurs during the attachment process of the ignition coil. An investigation of the possibility of manufacturing the mounting tool with a 3D-printer is undertaken in cooperation with ÅF, a consultant to Volvo Cars. A literature study is first presented to introduce broader knowledge on the subject. The abrasive wear and other material characteristics such as tensile strength, compressive strength and elongation of POM and an alternative material for 3D-printing, Ultem™, an amorphous thermoplastic polyetherimide are discussed. These material characteristics are studied further and considered in tandem with both a theoretical analysis and a wear experiment, based on the pin-on-disc method. It is shown in the theoretical analysis that the wear is approximately six times larger for Ultem™ when compared to POM. The wear resistance of Ultem™ is highest when wear occurs parallel to the direction of the printed layers. In contrast, the experiment shows that the wear is about three times larger in Ultem™ than in POM. The highest tensile strength of Ultem™ is also found in the direction of the printed layers. Some issues with the small elongation of the 3D-printed material are presented. It is recommended that ÅF apply the 3D-printing technique with Ultem™ only for construction details with complex geometries and where the material elongation will not exceed 5%. It is also recommended that ÅF both support and contribute to this innovative technique in order to develop leading edge competence in the subject.
Volvo Cars i Skövde tillverkar och monterar Volvomotorer. Vid monteringen av tändspolen till alla 4-cylindriga motorer behövs ett monteringsverktyg. Detta monteringsverktyg tillverkas för närvarande från formsprutad termoplast polyoximetylen (POM). Det har noterats att livslängden av verktyget förkortas på grund av abrasiv nötning som uppkommer under monteringsprocessen av tändspolen. Möjligheterna att tillverka monteringsverktyget med en 3D-skrivare utvärderas i samverkan med ÅF, en konsult till Volvo Cars. En litteraturstudie presenteras för att introducera en bredare kunskap i ämnet. Den abrasiva nötningen och materialegenskaper såsom draghållfasthet, tryckhållfasthet samt töjning hos POM och ett alternativt material för 3D-skrivning, Ultem™, en amorf termoplast polyeterimid, behandlas. Dessa materialegenskaper studeras vidare och tas i beaktning med både en teoretisk analys och ett nötningsexperiment, baserat på pin-on-disc metoden. Enligt den teoretiska analysen är nötningen hos Ultem™ approximativt 6 gånger större vid jämförelsen med POM. Nötningsbeständigheten hos Ultem™ är högst då nötning sker parallellt med 3D-skrivningsriktningen av lagren. Nötningsexperimenten visar att nötningen hos Ultem™ är ungefär 3 gånger större vid jämförelsen med POM. Den högsta draghållfastheten hos Ultem™ uppkommer också parallellt med 3D-skrivningsriktningen av lagren. Problem med den låga töjningen hos det 3D-skrivna materialet behandlas. ÅF rekommenderas att tillämpa 3D-skrivning med materialet Ultem™ främst för detaljer med komplexa geometrier med en töjning som inte överskrider 5 %. ÅF rekommenderas även att både stödja och bidra till denna innovativa teknik för att kunna skapa en ledande expertis i ämnet.

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15

Silva, Rafael Luís da. "Aços resistentes ao desgaste abrasivo para ferramentais de macharia cold box". Universidade do Estado de Santa Catarina, 2015. http://tede.udesc.br/handle/handle/1675.

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Sand cores are widely used at automotive foundries. The impact of sand on the surface of the tooling caused by the injection pressure causes wear on internal geometry, that interferes in the assembly of sand cores and dimensional of casting, and the maintenance of tooling is a bigger concern of the automotive foundries. When a core box show wear, some procedures may be applied for re-use of tooling, but, however, a better understanding of the wear process that occurs on the surface of the inserts will improve the life time of the core box. The purpose of this study is to better understand the wear mechanism that suffers tooling and form a knowledge base of wear on foundry tooling. In this study was present a comparative study on wear resistance among 05 different types of steels used in the manufacture of foundry tooling. The wear resistance has studied by tests on steel specimens used in the manufacture of foundry tooling in the rubber wheel abrasometer, as the pattern set by the technical ASTM G65-04.
Núcleos de areia são largamente utilizados em fundições de peças automotivas. O impacto da areia sobre a superfície do ferramental causado pela injeção sob pressão provoca desgaste na sua geometria interna, o que interfere na montagem dos núcleos de areia e dimensional da peça fundida, sendo que, a manutenção dos ferramentais é uma das grandes preocupações da fundição de peças automotivas. Quando uma caixa de macho apresenta desgaste, certos procedimentos podem ser aplicados para reutilização do ferramental, mas, no entanto, o melhor conhecimento do processo de desgaste que ocorre na superfície dos insertos irá melhorar a vida útil da caixa de macho. O objetivo do trabalho é entender melhor o mecanismo de desgaste que o ferramental sofre e formar uma base de conhecimento sobre desgaste em ferramentais de fundição. Neste trabalho foi realizado um estudo comparativo na resistência ao desgaste entre 05 diferentes tipos de aços utilizados na confecção de ferramentais de macharia Cold Box. A resistência ao desgaste foi estudada através de testes em corpos de prova de aços utilizados na fabricação de ferramentais em abrasômetro do tipo roda de borracha, conforme o padrão estabelecido pela norma técnica ASTM G-65-04.

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16

Eve, R. W. "The abrasive wear of carbon materials". Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377203.

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17

Jewell, Gavin. "Three-body abrasive wear of materials". Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/7669.

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Includes bibliographical references.
This work is an investigation into the phenomenon of three-body abrasive wear. A specially designed three body abrasive wear apparatus has been built, modified and evaluated as part of this overall study. Further, a series of commercially available candidate materials has been evaluated for wear resistance using silica sand as the abrasive on this purpose made rig. The effect of normal load, abrasive particle size, abrasive feed rate and the type of abrasive on three body wear resistance has also been examined. It has been shown that there is little increase in wear with an increase in particle size in the size range from 50µm to 180µm and that above an abrasive particle size of approximately 200µm there is a sharp decrease in the wear with increasing particle size, followed by a levelling off in the wear. The wear was found to increase linearly with increasing load. Varying the abrasive feed rate showed that at lower feed rates the abrasive particles were more efficient at removing materials, so the wear was higher than at higher abrasive feed rates. It has also been shown that although the use of ash from coal-fired power stations as an abrasive produces wear of materials, the volume losses were much smaller than those obtained using silica sand and thus it is considered that the tests using silica gave results which were more reliable. The volume losses of alumina ceramics abraded against ash were insufficient to give reliable wear test data and it was concluded' that ash could not be used to rank materials of high hardness. A number of materials were ranked for wear resistance using silica sand abrasive particles. The alumina ceramics and tungsten carbide composite materials showed the best wear performance.

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18

Qi, Hang 1971. "Mechanics of abrasive wear of elastomeric materials". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29994.

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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references.
Elastomeric materials are widely used as tire and sealing materials due to their ability to undergo large deformations and conform to the mating surface. However, their applications often result in repeated contact with abrasive particles, which act to abrasively wear the elastomers. Elastomeric materials are observed to exhibit a characteristic form of abrasive pattern on the surface after cyclic scratching. The dimension of this pattern is closely related to the wear rate, whereas the formation of this pattern is controlled by abrasive particle sizes, material mechanical properties, loading conditions, thermal conditions, and chemical degradation of materials. Much research has been conducted in the past. However, direct observations of the wear process are rare. The mechanics underlying the abrasive wear of elastomeric materials is unclear. In order to provide fundamental understanding of the abrasive wear of elastomeric materials due to abrasive particle indentation and scratching, this research studied the wear of elastomeric materials subjected to scratching by knife geometries that simulate abrasive particles and contact conditions. Efforts were focused on establishing direct observations and analysis of the deformation mechanics. An in situ micro scratching test capability operating within a scanning electron microscope (SEM) was developed and used together with image processing to reveal the local deformation fields. Surface profile analyses using both SEM and ZYGO (a non-contact interferometer) were also conducted to observe the surface change during cyclic scratching. The large strain nonlinear stress-strain behavior of thermoplastic polyurethanes (TPUs) exhibits strong hysteresis, rate dependence and cyclic softening.
(cont.) In this work, a constitutive model capturing the major features of the stress-strain behavior of TPUs was developed. The model decomposed material behavior into an equilibrium component and a rate dependent deviation from equilibrium. The cyclic softening behavior was attributed to be due to the softening of the equilibrium path as a result of the evolution of the effective volume fraction of the soft domain during deformation, upon which the occluded soft material was released to carry load due to the relative motions among hard domains. Extensive finite element (FE) based simulations of indentation and scratching tests using the proposed constitutive model were conducted. The FE model was verified by comparing the variation of normal and tangential forces and the distributions of displacement and strain fields with those experimentally obtained. The FE simulations revealed that the transition from the stick phase to the slip phase during scratching was accompanied by a large increase in molecular stretch and maximum principal stress (tensile stress), thus creating conditions for damage initiation. The FE model was then used to investigate the effects of contact conditions, cyclic scratching, friction, scratching speed, and material properties on the variation of molecular stretch and maximum principal stress. The effects of fiber fillers were also investigated by considering three representative fiber orientations: Horizontal, vertical, and lateral orientations. It was found that, for the fiber geometries and abrasive particle geometries studied, fibers do not enhance material wear resistance.
by Hang Qi.
Sc.D.

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19

Jackson, Mark James. "A study of vitreous-bonded abrasive materials". Thesis, Liverpool John Moores University, 1995. http://researchonline.ljmu.ac.uk/5096/.

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This thesis has focused primarily on the effect of bond and workpiece composition on the performance of vitreous-bonded alumina grinding wheels. The effect of bond composition considered in this work can equally be applied to grinding wheels which use silicon carbide (carborundum) as the abrasive medium. The bonds considered in this study are described as sintering bonds (high clay content), used in silicon carbide grinding wheels, - and fusible bonds (high glass content), used in vitreous bonding systems suitable for use in aluminium oxide grinding wheels. The initial part of the research work deals with a review of the mechanisms of grinding and the evaluation of wheel performance. The effect of grinding conditions, abrasive compositions, and workpiece material composition on the mechanisms of grinding wheel wear in conventional wheels was studied. The analysis of grinding wheel wear was examined and compared with experimental data. Reactions in grinding wheel bond materials were examined by comparing theoretical equilibrium compositions with actual reaction products using experimental techniques such as x-ray powder methods and differential thermal analysis. Experimental studies were carried out to investigate the vitrification behaviour of sintering and fusible bonds. This was achieved by examining the relationship between theoretical equilibrium liquid and silica contents and experimental vitrification conditions. A semi-empirical model was developed for determining optimum firing conditions for sintering and fusible bonds. The effect of bond composition on the strength of sintering and fusible bonds, under fixed firing conditions, was investigated. This resulted in some bonds failing by cracks around quartz particles, whilst bonds with high glass contents failed by a combination of pore-flaws. A model was also developed which predicted the amount of quartz remaining after heat treatment. The model was shown to be accurate when compared with experimental data. Based on the results of the experimental work on bond characterisation, the effect of bond and workpiece composition was compared with grinding wheel performance data. This was achieved by grinding a variety of hardened tool steels with abrasive segments manufactured with optimised grades. An empirical model was developed which showed that wheel wear was a function of bond strength and the nature of complex carbides present in the microstructure of the tool steels.

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20

Kayatz, Fabian y Ronald Claus. "Reibmessgerät zur Bestimmung des Gleitreibkoeffizienten von bahnförmigen Packstoffen". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-178250.

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21

Quirke, SJ. "Abrasive wear testing of steels in soil". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/21798.

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Bibliography: pages 133-136.
A survey has been made of the quality and type of materials used for tillage tools in South Africa. Conclusions have been drawn regarding the inadequacy of the manufacturing processes used and the resultant quality of the tool material. A rig has been designed for the abrasion testing of materials in soil. The reproducibility of the method has been shown to be high and an evaluation has been made of the relative wear resistance of a series of ·heat treated steels. A medium carbon boron steel has been shown to have great promise as a tillage tool material because of its high wear resistance and toughness. The deformed surface layers and the mechanisms of wear of steels subjected to field and laboratory abrasive testing has been examined. The removal of material through predominantly ploughing or cutting mechanisms has been shown to be dependent on the heat treatment and composition of the steels together with the nature of the abrasive. White surface layers have been observed to form on medium and high carbon steels subjected to soil abrasion. Suggestions have been advanced for their formation. Attempts have been made to assess the transferability of data between field and laboratory testing.

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22

Allsopp, D. N. "Abrasive wear of bulk materials and hard coatings". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595477.

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Thin coatings and other surface engineering techniques are widely used to improve the friction and wear properties of surfaces. However, current understanding of the behaviour of surfaces is relatively poor. Production methods are therefore to a large extent based upon empiricism. Many well-established materials characterisation tests are inadequate, and so novel techniques for the examination of surface layers have emerged, with the eventual aim of predicting the tribological performance of surfaces. One such technique is the micro-scale abrasive wear test, in which a ball is rotated against a specimen in the presence of a slurry of fine abrasive particles, producing a well-defined crater whose volume may be measured geometrically, allowing the wear coefficient of the specimen to be determined. It has been shown that the existing understanding of test is inadequate; further characterisation of the test has been performed. The effects of various parameters on the mechanism and severity of wear have been identified and explained by adaptation of existing models. Recommendations have been made for the optimisation of the accuracy and reproducibility of the test. The capability of the test to characterise thin coatings has been extended by shallow ball-crater testing which does not penetrate though the coating, thereby eliminating any influence of the substrate wear resistance. A number of different formulations of the wear equation, and a number of data analysis methods have been discussed, with the aim of minimising error. Since many surface coatings are exposed to high temperatures in service, the micro-scale abrasion test and the commonly used scratch test have been adapted for use at elevated temperatures in order to investigate changes in coating properties under these conditions. A new scratch test apparatus was designed and constructed for these tests. The behaviour of various PVD coatings has been investigated by these methods.

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23

Pintaúde, Giuseppe. "Análise dos regimes moderado e severo de desgaste abrasivo utilizando ensaios instrumentados de dureza". Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-07042010-111922/.

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Este trabalho apresenta uma metodologia experimental para investigar a relação entre taxas de desgaste abrasivo e dureza. Investigam-se os regimes moderado e severo de desgaste abrasivo em função da razão entre a dureza do abrasivo (HA) e a dureza do material desgastado (H). Foram realizados ensaios pino contra lixa, utilizando vidro como abrasivo em dois tamanhos, grana #80 e grana #240, e pinos com 3 mm de diâmetro sob força de 20 N. Os materiais ensaiados foram os aços AISI 1006 e AISI 52100, este último em diferentes condições metalúrgicas, e um ferro fundido branco de alto cromo, de composição eutética e matriz perlítica. Três tipos de resposta do sistema tribológico foram utilizadas para avaliar os regimes de desgaste: perda de massa, coeficiente de atrito e força de penetração do abrasivo. Determinaram-se as perdas de massa ao longo dos ensaios; o coeficiente de atrito medido por meio de célula de carga e a força de penetração com o uso de ensaios instrumentados de dureza estimando-se a profundidade máxima de penetração com base no parâmetro Rz. A partir das medidas de dureza, foi utilizado um parâmetro para incorporar os efeitos do comportamento elasto-plástico dos materiais, que considera a morfologia de impressão de dureza. Com este parâmetro, foi possível obter uma dureza denominada \"verdadeira\", que incorpora os efeitos de formação de bordas ou retração dos materiais. Verificou-se que os valores de resistência ao desgaste relativa não dependem do tamanho do abrasivo, mas que os valores de coeficiente de atrito dependem, sob regime severo de desgaste. Por sua vez, no regime moderado, os valores de coeficiente de atrito são independentes do tamanho do abrasivo.
This work presents an experimental methodology to investigate the relationship between abrasive wear rates and hardness. The mild and severe abrasive wear regimes are investigated in relation to the abrasive hardness-to-worn material hardness ratio (HA/H). Pin-against-paper tests were performed, using glass as abrasive material in two grain sizes, grit #80 and grit #240, and 3-mm diameter pins under 20 N of applied load. The tested materials were AISI 1006 e AISI 52100 steels, the last one in different metallurgical conditions, and a high-chromium white cast iron, with eutetic composition and pearlitic matrix. Three kinds of tribological system responses were used to evaluate the wear regimes: mass loss, friction coefficient and load of penetration of abrasive. Mass losses were determined along testing time; friction coefficient was determined by means of load cell and the load of penetration using instrumented hardness test, selecting the maximum depth penetration based on the Rz roughness parameter. From hardness measurements, a parameter was used to incorporate the elastic-plastic behavior of materials, which consider the indentation hardness morphology. Using this parameter, it was possible to obtain a kind of hardness called \"true\", which incorporate the pilling-up and sinking-in effects. It has been demonstrated that the relative abrasive resistance is not dependent of the abrasive particle size, but the friction coefficient values change, under severe wear regime. On the other hand, under mild regime, the friction coefficient values are independent of the abrasive particle size.

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24

Sole, Brian Michael. "The abrasive wear behaviour of mineral-filled polypropylene". Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9545.

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Bibliography: leaves 170-179.
Polypropylene is an extremely versatile polymer because its properties can be modified to meet specific requirements. The use of polypropylene in domestic and automobile applications has initiated research focused on the tribological behaviour of the material. In the present study, polypropylene grades have been subjected to both mild and severe abrasive wear conditions with specific emphasis on the surface property of scratch resistance. The experimental work has covered the effect of polymer crystallinity, mineral fillers, and the nature of the abrasive counterface on the wear behaviour of polypropylene. The wear behaviours of polymethylmethacrylate, polycarbonate, acrylonitrile-butadiene-styrene, and high density polyethylene have been determined for comparative purposes. The abrasive wear rates have been measured and the material deformation and removal mechanisms have been identified and characterised in terms of the physical properties of the polymer and the individual fillers, and in terms of the macroscopic mechanical behaviour of the filled composite materials. Investigative techniques used in this study included mechanical testing, optical and scanning electron microscopy, surface profilometry, and differential scanning calorimetry. Under two-body abrasive wear conditions, the unfilled and modified polypropylene materials exhibit a ductile mode of material deformation and removal.

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25

Kayatz, Fabian y Ronald Claus. "Reibmessgerät zur Bestimmung des Gleitreibkoeffizienten von bahnförmigen Packstoffen". Rek & Thomas Medien AG, 2014. https://slub.qucosa.de/id/qucosa%3A7337.

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26

Marin, John Jairo Coronado. "Efeito do tamanho do abrasivo no desgaste de metais". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-23082010-105321/.

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Neste trabalho, foi investigado o efeito do tamanho do abrasivo na resistência ao desgaste de cinco ligas metálicas. Foi usado, para este estudo, o equipamento pino contra lixa e alumina como abrasivo, com tamanho médio entre 16 µm e 192 µm. A microestrutura das ligas metálicas foi caracterizada com microscopia ótica e os mecanismos de desgaste abrasivo e os microcavacos (partículas de desgaste) foram caracterizados usando microscopia eletrônica de varredura (MEV). Em uma primeira série de experimentos, foi usado ferro fundido mesclado com carbonetos M3C (temperado e revenido a temperaturas entre 300 e 600°C). Para abrasivos pequenos, a perda de massa elevou-se com o aumento do tamanho do abrasivo. Entretanto, para abrasivos grandes, a perda de massa aumenta com inclinação menor e o mecanismo prevalente de desgaste é o microcorte. Para abrasivos maiores, o mecanismo prevalente de desgaste é microsulcamento. Em uma segunda série de experimentos, foi usado ferro fundido branco (FFB), com matrizes austenítica e martensítica. O FFB com matriz austenítica apresentou um tamanho crítico de abrasivo (TCA) de 36 µm e, para o ferro fundido martensítico, foi aproximadamente de 116 µm. A perda de massa do ferro fundido com matriz austenítica aumentou linearmente com o aumento do tamanho dos abrasivos, após o TCA a perda de massa aumenta com inclinação menor. O FFB martensítico, com menores tamanhos do abrasivo, apresentou um comportamento linear. Existe, porém, uma região de transição não-linear e achatada, quando o tamanho de partícula crítico é atingido, tornando-se independente do tamanho do abrasivo. Antes do TCA, o micromecanismo prevalente de desgaste foi microcorte e a lixa apresentou cavacos contínuos e finos e, após o TCA, o mecanismo prevalente de desgaste foi microsulcamento e apresentou cavacos descontínuos e deformados. O efeito do tamanho de abrasivo observado na perda de massa foi apresentado na energia especifica de corte e no coeficiente de atrito. Em uma terceira série de experimentos, foi usado alumínio e aço AISI 1045. O alumínio (estrutura cristalina cúbica de fase centrada) apresentou um comportamento similar ao observado no FFB com matriz austenítica, e o aço AISI 1045 apresentou um comportamento similar ao FFB com matriz martensítica. Verificou-se que, no alumínio e no aço AISI 1045, também se apresenta mudança na morfologia dos cavacos e nos micromecanismos de desgaste, observados nos materiais com segunda fase dura. Em uma quarta série de experimentos, foi usado o ferro fundido cinzento para corroborar a mudança dos micromecanismos de desgaste abrasivo e dos microcavacos com o TCA. O ferro fundido cinzento não apresentou uma transição (TCA) na curva de tamanho de abrasivo contra perda de massa. A morfologia dos cavacos foi similar para os diferentes tamanhos de abrasivos (descontínua). Para abrasivos menores, porém, apresentaram-se alguns cavacos contínuos e finos. O micromecanismo prevalente de desgaste abrasivo foi de microcorte para os diferentes abrasivos usados. Portanto, nesta pesquisa, foi demonstrado que o tamanho crítico de abrasivo está relacionado com os micromecanismos de desgaste e com a morfologia dos microcavacos.
In this research, the effect of abrasive size on the wear resistance of five metallic materials was investigated. Abrasive wear tests using a pin test on alumina paper were carried out using abrasive sizes between 16 µm and 192 µm. The wear surface of the specimens was examined by scanning electron microscopy for identifying the wear micromechanism and the type of microchips formed on the abrasive paper (wear debris). In a first series of experiments mottled cast iron samples with M 3 C carbides were tested. The samples were quenched and tempered in temperatures ranging from 300°C to 600°C. For small abrasive particles, the wear mass loss increased linearly with the increase of particle size. However, for higher abrasive sizes the wear mass loss increased much more slowly. For lower abrasive sizes the main wear mechanism was microcutting. For higher abrasive sizes, the main wear mechanism was microploughing. In a second series of experiments white cast iron with M 3 C carbide with austenitic and martensitic matrix were tested. The results show that the mass loss for cast irons with austenitic and martensitic matrices increases linearly with the increase of particle size until the critical particle size is reached. The cast iron with austenitic matrix presented a critical abrasive size of 36 µm and for the martensitic cast iron, the critical particle size was about 116 µm. After the critical particle size is reached, the rate of mass loss of the cast iron with austenitic matrix diminishes to a lower linear rate, and for cast irons with martensitic matrix the curve of mass loss is non-linear and flattens when the critical particle size is reached. It becomes, then, constant, independent of additional size increases. The abrasive paper in contact with the iron of both austenitic and martensitic matrices presents fine continuous microchips and the main wear mechanism was microcutting before reaching critical particle size, and after that it presents deformed discontinuous microchips and the main wear mechanism was microploughing. This behavior of change in rates after reaching a critical size happened not only for mass loss versus abrasive size, but it was also observed both in curves of friction coefficient and specific cutting energy versus abrasive size. In a third series of experiments aluminum and AISI 1045 steel were tested. The first (FCC structure) showed similar behavior to that observed in the white cast iron with austenitic matrix and the latter showed similar behavior to that observed in white cast iron with martensitic matrix. Both aluminum and AISI 1045 steel show similar changes in the microchips morphology and in the wear micromechanisms, something that had been observed before in materials with hard second phase. In a fourth series of experiments gray cast iron was tested in order to demonstrate the relationship between the abrasive wear micromechanisms and the type of microchips, before and after achieving critical abrasive size. The grey cast iron did not show a transition in the curve of abrasive size against mass loss. The morphology of the chips was similar for the different sizes of abrasive (discontinuous). However, smaller abrasive sizes some thin continuous microchips were formed. The main abrasive wear micromechanism was microcutting for the different abrasives sizes tested. Therefore, it was shown that the critical abrasive size is related to the wear micromechanisms and the microchips morphology.

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27

Scheffler, O. "The influence of steel microstructure on abrasive wear in soils". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/17646.

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Bibliography: pages 96-104.
A hypoeutectoid steel has been heat treated to produce a range of different hardnesses and microstructures. A simulative field test rig has been employed to determine the relationship between microstructural parameters, material properties and soil constitution. Attempts have been made to correlate the ranking order for the wear resistance of similar treated steels in field and laboratory tests. It has been established that wear resistance is a function of soil constitution, steel carbide morphology and hardness. Explanations have been advanced for the differences in the wear resistance of similar steels in different soils based on the mechanism of material removal. Recommendations have been made regarding the selection of steel microstructure for varying soil conditions.

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28

Wallin, Harald. "An investigation of friction graphs ranking ability regarding the galling phenomenon in dry SOFS contact : (Adhesive material transfere and friction)". Thesis, Karlstad University, Faculty of Technology and Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2790.

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The main purpose of this project is to investigate different tool steels in terms of their ability to withstand material transfer buildup, so-called galling, occurring in SMF (sheet metal forming) operations. The ability to withstand galling is vital to optimize cost-effectiveness and increase the work tool’s effective operational time. This investigation studies four different tool steels, including a TiN-coating, with the intention of evaluating the microstructures, chemical composition and hardness effect on galling resistance in dry conditions using a slider-on-flatsurface (SOFS) tribo-tester which measures the coefficient of friction during sliding.

An OP (optical profilometer) was used to measure the size and geometry of lump growth on the tool and damage on the work sheet. A scanning electron microscope (SEM) was used to identify the interacting tribological mechanisms exhibited at different stages during the slide. The SEM figures confirmed three different types of characteristic patterns exhibited in the tracks after tribo- testing which were categorized as mild adhesive, abrasive and severe adhesive damage.

A SEM figure that illustrates a ragged contact surface and an obvious change in the sheet materials plastic behavior is in this report regarded as a sign of severe adhesive contact, the characteristics could possibly be explained by local high temperature and high pressure followed by a sudden pressure drop and creation of hardened welds or solders between the two surfaces which increase the frictional input needed for further advancement. Friction coefficients observed in the initial 100% mild adhesive stage were, μ=0,22-0,26 succeeded by abrasive SEM characteristics often in association with mild adhesive contact and friction values between μ=0,25-0,4 which where sometimes followed by severe adhesive SEM characteristics in 100% of the contact zone with friction values between μ=0,34- 0,9 respectively. The tool material that performed best according to the friction detection criteria was Sv21 closely followed by Sleipner (TiN coated) and Va40 (HRC 63.3). Unfortunately was the friction criteria, a significant raise in friction for defining a sliding length to galling, not adequate for dry conditions due to immediate material transfer succeeded by cyclic changes between partial or 100% abrasive+mild adhesive and severe adhesive contact. The mechanism that change abrasive wear in association with mild adhesive contact, (moderate friction input), to sever adhesive wear, (higher friction input), is dependent on lump shape (lump geometry) and can appear at comparably low speeds 0,04-0,08 [m/s] and low friction energy input (μ=0,34), the magnitude of the change in friction is therefore not always significant and hardly detectable on the friction graph. This was quite unexpected but could be explained by concentration of friction energy rater than the absolute amount. The problem with using friction graphs for galling evaluation was increased even further when a very small lump size and low corresponding rate of material transfer to the tool surface caused a sustainable high raise in friction (μ≈0,3→0,6) on a TiN-coated tool steel called Sleipner.

A hardly detectable or similar friction raise for Sv21 and Va40 showed much larger corresponding lump size and rate of material transfer. This means that friction graphs demonstrate a clear problem with quantifying lump size [m3] and rate of material transfer [m3/s]. Another phenomenon called stick slip behavior, material transfer and lump growth followed by a sudden decrease in lump size and transfer of material back to the work sheet, is also not possible to detect on a friction graph. Because a drop in friction can easily be a change in contact temperature and lump attack angle due to a growing lump and not a decreasing lump.

The conclusion, a friction graph is not suited for galling evaluation and ranking in dry SOFS conditions. A ranking should primarily be based on dimensional OP measurements of the cross section of formed tracks and scratches or preferably by repeated OP measurements of the tool surface during a single test, the last revel the exact lump growth history and true lump growth even in the sliding direction.

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29

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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30

Meyer-Rödenbeck, G. D. "An abrasive-corrosive wear evaluation of some aluminium alloys". Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/18784.

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This investigation evaluates the abrasive-corrosive wear behaviour of aluminium alloys with the aim of establishing a data base of performance and guide lines for material optimisation. Wear test apparatus and standard tests developed by previous research programmes were utilised (Noel and Allen, 1981; Barker, 1988). Further tests were then devised for a more detailed characterisation of wear behaviour. Tests conducted showed that aluminium alloys have approximately a quarter to half the abrasion resistance of mild steel. Poor microfracture properties of Al-Si cast alloys were observed as a result of coarse and brittle silicon rich phases contained in the aluminium matrix. Non heat-treatable wrought alloys exhibit ductile micro-deformation characteristics whilst heat-treatable alloys, having the best abrasion resistance, possess better combinations of strength, hardness and toughness. Tests with combined corrosion and wear showed that most aluminium alloys are subject to pitting corrosion due to localised differences in electrode potentials at constituent sites. Higher series alloys with a large number of constituent particles exhibit higher pitting densities. Due to the high electrode potentials of silicon phases and copper and zinc solid solutions, the alloys LM6+Sr, 2014 and 7075 have poor corrosion resistance and are subject to localised and pitting attack. As a consequence the alloys 2014, 7075 and LM6+Sr show a decrease in wear performance under abrasive-corrosive conditions. In contrast the good corrosion resistance of the alloys 5083, 6261 and 7017 provide a significant improvement in wear performance under conditions of long corrosion periods with light abrasive intervals. This study concludes that the abrasion resistance of wrought alloys may be optimised by designing an alloy with a good combination of tensile strength, fracture toughness and hardness together with an intermediate microstructural size distribution of second phase particles in the aluminium matrix. Ageing of heat treatable alloys improves abrasion resistance significantly, peak hardness and strength conditions resulting in optimum abrasion properties.

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31

Guo, Zihong. "Experimental and numerical analysis of abrasive waterjet drilling of brittle materials /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/7092.

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Santos, Aliandro Henrique Costa. "Avaliação do desempenho de pastilhas automobilisticas nacionais". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264005.

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Orientador: Auteliano Antunes dos Santos Junior
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia mecanica
Made available in DSpace on 2018-08-04T10:30:47Z (GMT). No. of bitstreams: 1 Santos_AliandroHenriqueCosta_M.pdf: 10616712 bytes, checksum: 57733fcc9ba5b442556901d87af2a403 (MD5) Previous issue date: 2005
Resumo: Os freios utilizados para veículos são normalmente por atrito. A tendência internacional é no sentido de utilizar somente freios por atrito à disco, eliminando os atuais tambores empregados em rodas traseiras para automóveis de passageiros. O aumento do desempenho de veículos automotivos e a conseqüente alteração em suas características dinâmicas tem levado a criação de sistemas de freio mais eficientes. A expansão do mercado para pastilhas e a necessidade de redução de custos tem levado ao surgimento de materiais sem a qualidade necessária para o desempenho da frenagem. Os procedimentos de ensaio existentes hoje e que permitem avaliar a qualidade do material de atrito são complexos e normalmente fazem uso de dinamômetros com inércia, de custo muito elevado e não disponíveis nos centros e instituições de pesquisa brasileiras. Este trabalho teve como objetivo caracterizar o desempenho de materiais de atrito para pastilhas de freio através da criação de um procedimento de ensaio que englobe as principais variáveis que influenciam o processo de frenagem. Foi utilizado o Dispositivo de Ensaio de Amostras, dinamômetro de baixo custo disponível no Departamento de Projeto Mecânico da FEM-Unicamp. Um planejamento experimental ortogonal L9 permitiu o estudo da influência de variáveis envolvidas no processo de utilização de pastilhas, que são a marca, o fornecedor, a pressão específica, a velocidade e a temperatura, em dois níveis de desgaste. Os resultados mostram que o procedimento proposto pode ser utilizado na avaliação da qualidade do material de atrito de pastilhas, de forma rápida, eficiente e com baixo custo
Abstract: Automotive brake systems are mainly friction based. The world tendency is toward using disc brakes instead of drum brakes, which are usually installed in the rear wheels. The increase in the performance of automotive vehicles and the changes in the dynamic characteristics have conducted to more efficient brake systems. The expansion of the brake pads market has impacted the quality of the products. Low quality products have been found, specially were no control exists. The actual test procedures to evaluate the quality of rnction materials are compIex and most of them require a fuII scale inertial dynamometer. Those machines are very expensive and most of the Brazilian research and quality centers do not have them. This work aimed to deveIop a procedure to characterize the performance of brake pads and analyzing the main factors of influence. A Iow cost non-inertial dynamometer, called D.E.A. - Fixture to text sampIes of friction material, was used. It is instalIed in the Department of Mechanical Design - FEM of the State University of Campinas, in Brazil. An experimental orthogonal design L9 was used to take the factor of influences in account. They are identified and the main factors are: contact pressure, disc speed, temperature and pad manufacturer. The influences were evaluated in two leveI of pad wearing. The results show that the procedure can be used to evaluate the quality of the rnction material for brake pads, in a fast and not expensive way
Mestrado
Projeto Mecanico
Mestre em Engenharia Mecânica

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33

Ferrendier, Sophie. "Influence de l'évolution granulométrique des abrasifs sur l'enlèvement de matière lors de la découpe par jet d'eau abrasif". Phd thesis, Paris, ENSAM, 2001. http://tel.archives-ouvertes.fr/tel-00005625.

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Nous proposons une méthode permettant de prédire les hauteurs de coupe lors de la découpe de laiton par jet d'eau abrasif. Les modèles d'enlèvement de matière précédemment développés font abstraction de la taille de l'abrasif et montrent leurs limites dans le cas de découpes réalisées avec des abrasifs fins d'un diamètre moyen proche de 100 microm. Nous avons décidé de rapprocher les caractéristiques des abrasifs des performances de coupe pour développer un modèle plus précis tenant compte de la granulométrie de l'abrasif en sortie de tête de mélange. Pour cela, nous avons conduit une série d'expérimentations visant à mettre en évidence l'évolution des caractéristiques géométriques et granulométriques de deux abrasifs de découpe de type grenat (Barton et GMA) au cours de leur passage dans la tête de mélange. Nous avons utilisé la vidéomicroscopie pour obtenir les caractéristiques géométriques que sont l'allongement et la circularité ; les distributions de taille des échantillons ont été définies par granulométrie laser. Le phénomène de fragmentation de l'abrasif au cours du processus de mélange se traduit par un effilement des particules abrasives qui, selon les cas, leur confère ou leur permet de conserver un plus grand pouvoir érosif. Nous avons introduit ces caractéristiques dans un nouveau modèle d'enlèvement de matière. Celui-ci s'étend à une large gamme de pressions, jusqu'à 380 MPa, et à une large game de granulométries d'abrasif, jusqu'à 470 microm. Il permet de déterminer la hauteur de coupe prévisible en fonction notamment de la fraction X de particules abrasives particpant au mode d'enlèvement de matière d'érosion par déformation. Cette fraction, fonction de l'évolution de la granulométrie des abrasifs au cours du processus de mélange, est définie par un modèle spécifique.

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34

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.

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35

Ramakrishnan, Easwar Vinayak. "An Investigation into 'Squeezing'or Three-Body Wear caused by Abrasive Particles". Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-283552.

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Material wear is an ever present phenomenon and can never be completely removed in systems of moving parts. There will always be friction between materials, causing degradation of these materials and eventually the material will be worn out and have to be replaced. In industrial applications, the cost of failure of a material is severe and thus it is important to understand how long a material will operate at a certain working condition. Thus in order to be able to predict the life of a material, the wear mechanisms of the application need to be understood. Squeezing wear or three body wear is a phenomenon occurring when abrasive particles are rolling between two material surfaces. This is not a well researched field, especially when it concerns two steel surfaces with abrasives present between them. Thus the objective of this study was to observe the effect of abrasive particles on the wear of the materials. For this purpose, pin and disk wear tests were conducted both in the presence and absence of abrasive particles. The results show that the abrasive particles act as a buffer between the two materials and hence the specific wear rate observed when the abrasive particles are present is far lesser than the specific wear rate in their absence. Thus this confirms previous research findings that the rate of wear in three body abrasion is lower than the wear rate in two body abrasion. Adhesive wear was observed in one of the material combinations in the absence of abrasive particles. This is a severe type of wear and occurs at far higher rate than observed for two-body or three-body abrasion.
Materialslitage är ett ständigt närvarande fenomen och kan aldrig tas bort helt i system med rörliga delar. Det kommer alltid att finnas friktion mellan material, vilket orsakar nedbrytning av dessa och så småningom kommer materialet att bli utslitet och måste bytas ut. I industriella applikationer är kostnaden för att materialet går sönder stora och det är därför viktigt att förstå hur länge ett material kommer att fungera vid ett visst arbetsförhållande. För att kunna förutsäga livslängden för ett material måste således slitagemekanismerna för applikationen förstås. Klämslitage eller slitage på tre kroppar är ett fenomen som uppstår när slipande partiklar rullar mellan två materialytor. Detta är inte ett välundersökt område, speciellt när det gäller två stålytor med slipmedel närvarande mellan dem. Således var målet med denna studie att observera effekten av slipande partiklar på materialets slitage. För detta ändamål utfördes ”pinne på disk” förslitningstester, både i närvaro och frånvaro, av slipande partiklar. Resultaten visar att de slipande partiklarna fungerar som en buffert mellan de två materialen och följaktligen är den specifika nötningshastigheten som observeras när de slipande partiklarna är närvarande mycket lägre än den specifika nötningshastigheten i deras frånvaro. Detta bekräftar sålunda tidigare forskningsresultat att slitaget vid trekropparsnötning är lägre än vid tvåkropparsnötning. Adhesiv nötning observerades i en av materialkombinationerna i frånvaro av slipande partiklar. Detta är en allvarlig typ av slitage och uppträder i mycket högre takt än observerat för nötning mellan två eller tre kroppar.

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36

Black, Sean C. E. "The effect of abrasive properties on the surface integrity of ground ferrous materials". Thesis, Liverpool John Moores University, 1996. http://researchonline.ljmu.ac.uk/5100/.

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The effect of the thermal properties of alumina and CBN abrasives on workpiece temperatures in grinding was investigated. A review of the literature revealed a lack of knowledge of the thermal properties of CBN limiting the accuracy of theoretical predictions of the heat conduction in CBN grinding. A grain contact analysis was developed to predict the energy partitioning between the workpiece and wheel. The analysis takes into account two dimensional transient heat transfer in the grain and maintains temperature compatibility at the grain wear flatworkpiece interface. The proportion of the total grinding energy entering the workpiece, termed the partition ratio, was estimated by correlating measured temperature distributions with theoretical distributions. The partition ratios when grinding with CBN were substantially lower than grinding with alumina wheels for a range of ferrous materials. The lower partition ratios with CBN grinding were attributed to the higher thermal conductivity of the CBN abrasive. The effective thermal conductivity of alumina and CBN grains were quantified by correlating the theoretical partitioning model with the measured results. The effective thermal conductivity of CBN was found to be considerably lower than the reported theoretical value albeit much higher than the effective thermal conductivity of alumina. A model to predict the background temperature in grinding was proposed based on the experimental findings. The thermal model takes into account a triangular heat flux distribution in the grinding zone, the real length of contact and experimentally validated grain thermal properties. The input parameters to the thermal model were specified. To avoid temper colours on the workpiece surface the maximum background temperature must not exceed 450 to 500deg. C. for commonly used ferrous materials.

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37

Almeida, Flávia Aparecida de. "Nano to micrometric grain sized CVD diamond for turning hard and abrasive materials". Doctoral thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2313.

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Doutoramento em Ciência e Engenharia de Materiais
O presente trabalho consistiu no desenvolvimento de ferramentas de corte de diamante CVD (Chemical Vapour Deposition) obtido na forma de revestimento em materiais cerâmicos à base de nitreto de silício monolítico (Si3N4) ou compósitos nitreto de silício-nitreto de titânio (Si3N4-TiN). A adição de TiN acima de 23 vol.% conferiu conductividade eléctrica ao compósito, na ordem de 1×10-1 W−1.cm-1, possibilitando a sua maquinagem por electroerosão. Duas técnicas foram utilizadas para o crescimento dos filmes de diamante: deposição química em fase vapor por plasma gerado por microondas, MPCVD (Microwave Plasma Chemical Vapour Deposition), e por filamento quente, HFCVD (Hot Filament Chemical Vapour Deposition). Previamente os substratos cerâmicos sofreram uma preparação superficial por diversos métodos: rectificação por mós diamantadas; polimento com suspensão de diamante (15μm); ataque da superfície por plasma de CF4; riscagem manual ou por ultra-sons com pó de diamante (0.5-1.0 μm). A caracterização das ferramentas revestidas envolveu: o estudo da qualidade e tensões residuais dos filmes de diamante a partir da difracção dos raios X e espectroscopia Raman; a análise da respectiva microestrutura e medida da espessura por microscopia electrónica de varrimento (SEM); a determinação dos valores de rugosidade dos filmes por microscopia de força atómica (AFM); e a avaliação da adesão dos filmes aos substratos por indentação com penetrador Brale. Foram obtidos filmes com granulometria que variaram da gama do diamante nanométrico (< 100 nm) até ao micrométrico convencional (3-12 μm), com consequências na rugosidade superficial do filme. Os filmes de diamante CVD apresentaram espessuras de 15 a 150μm. Os revestimentos apresentaram elevada adesão ao substrato, sendo que o melhor resultado foi atingido pelo diamante micrométrico, suportando um limite de carga aplicada de até 1600 N. O estudo do comportamento em serviço das ferramentas foi efectuado na operação de torneamento de metal duro (WC-Co) e de eléctrodos de grafite, com medição de forças de corte em tempo real por meio de um dinamómetro. Os ensaios foram realizados num torno CNC, em ambiente industrial, na empresa Durit (Albergaria-a-Velha), produtora de metal duro. Os modos de desgaste das ferramentas foram avaliados por meio de observação em microscopia óptica e electrónica de varrimento e o grau de acabamento da superfície maquinada por rugosimetria. A influência destes parâmetros foi estudada em termos das forças envolvidas em operações de torneamento, desgaste das ferramentas e do acabamento conferido à peça maquinada. Os melhores resultados do torneamento de metal duro foram atingidos pelas ferramentas com geometria de aresta em quina-viva, recobertas com os filmes de diamante de 100-200 nm de tamanho de grão, correspondentes às menores forças de corte (<150N), melhor qualidade da peça maquinada (rugosidade aritmética igual a 0,2 μm) e menor desgaste (flanco igual a 110μm). No torneamento de eléctrodos de grafite, as forças de corte foram baixas (< 20N), sendo que o principal modo de desgaste foi a formação de cratera na superfície de ataque (valor máximo igual a 22 μm). O fio da aresta de corte permaneceu inalterado (devido ao mínimo desgaste de flanco), sendo que as diferentes granulometrias do diamante não tiveram influência significativa no comportamento geral das ferramentas.
This work consisted on the development of CVD (Chemical Vapour Deposition) diamond cutting tools directly deposited on monolithic silicon nitride (Si3N4) based ceramics and silicon nitride-titanium nitride composites (Si3N4-TiN). A TiN content higher than 23 vol.% confers electric conductivity to the composite in the order of 1×10-1 W−1.cm-1, making possible its machinability by means of electrodischarge machining. Two techniques were used for diamond growth: Microwave Plasma Chemical Vapour Deposition (MPCVD) and Hot Filament Chemical Vapour Deposition (HFCVD). The substrate pre-treatment steps prior to diamond deposition were: grinding with diamond wheels; polishing with diamond suspension (15μm); chemical etching with CF4 plasma; manual scratching or ultrasonic bath scratching with diamond powder (0.5-1.0 μm) for seeding purposes. The diamond cutting tools characterization involved: study of the quality and the residual stress of the films by X ray diffraction and Raman spectroscopy; analysis of respective film microstructure and measurement of film thickness by scanning electron microscopy (SEM); quantification of film surface roughness by atomic force microscopy (AFM); evaluation of adhesion strength of the thin films to Si3N4 substrate by the indentation technique with a Brale indenter. The grain size of the films varied from nanometric (< 100 nm) to conventional micrometric (3-12 μm), therefore giving different surface roughness. The CVD diamond film thickness was in the range of (15-150 μm). The diamond films presented a high adhesion level to the Si3N4 ceramic substrates, the best results being achieved by the micrometric grain sized film, which undergo a normal load of until 1600N. The study of the cutting tool behaviour was performed in turning operations of hardmetal (WC-Co) and graphite electrodes, by real-time acquisition of the cutting forces using a dynamometer. The turning operations were carried out in a CNC lathe, at industrial environment of a hardmetal producer company, Durit (Albergaria-a-Velha). The wear modes of the tested cutting tools were analysed by optical and electronic microscopy observations and the finishing quality of the machined workpiece was measured by surface roughness measurements. The influence of these parameters was studied in terms of the cutting forces developed during turning operations, of tool wear and of the finishing quality of the machined workpieces. The best results attained in hardmetal turning were achieved by the cutting tools with sharp edges, covered with diamond films of 100-200 nm of grain size, which presented the lowest cutting forces (<150N), the best workpiece surface quality (Ra=0.2μm) and the lowest flank wear (110μm). In graphite turning, the cutting forces were very low (<20N) and the main wear mode was the crater one on the rake face (maximum value of 22μm). The cutting edge remained almost intact (due to the minimum flank wear) while the different diamond grain sizes did not have a significant influence on the overall cutting behaviour.

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38

Ngakane, M. "Abrasive wear resistance of ruthenium aluminide intermetallic and ferritic steels containing a sigma intermetallic phase". Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9696.

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Bibliography: leaves 106-113.
The abrasive wear resistance of ruthenium aluminide intermetallic and ferritic steel containing an iron-chrome sigma intermetallic phase have been investigated in this study. A medium carbon wear resistant steel (MCV) was used in the study to facilitate comparison between wear resistances in the materials of interest. Specimens of ruthenium aluminide, MCV and ferritic stainless steels containing a sigma phase were produced. The MCV steel was quenched and tempered to match the bulk hardness of the as-received ruthenium aluminide. Five different grades of thermomechanically worked ferritic steels specimens were heat treated to produce different volume fractions of sigma phase. The mechanical properties of the specimens were investigated by compression testing and microhardness measurements. Abrasion testing was carried out on a pin on belt abrasion apparatus. The surface response of the specimens to abrasive wear was characterised by optical and scanning electron microscopy. Microhardness of the specimens were measured with a digital microhardness machine. The wear resistance of ruthenium aluminide was found to be higher than all materials tested in this project. The wear resistance in some of the ferritic steels containing sigma phase was comparable to that of the wear resistant medium carbon steel. The surfaces of the specimens were shown to work-harden during the abrasion process. The corresponding work-hardening results showed that ruthenium aluminide had the highest work-hardening rate. It can be concluded that the work-hardening ability of the test materials correlates with their respective wear resistance properties.

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39

Varasquim, Francisco Mateus Faria de Almeida [UNESP]. "Efeitos da granulometria, do desgaste e do tipo de material abrasivo no lixamento plano de madeiras". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/111072.

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O processo de lixamento é indispensável para situações onde os processos anteriores de fabricação não foram capazes de garantir as dimensões finais da peça produzida ou quando a qualidade superficial desejada não foi atingida. Este processo é muito usado em indústrias de painéis e de móveis, no entanto, quase sempre é empregado de forma empírica, sem o conhecimento adequado. No presente trabalho analisou-se a influência da granulometria, do desgaste abrasivo e do material abrasivo no lixamento plano da Corymbia citriodora e do Pinus elliottii. O objetivo do trabalho foi estudar e compreender a correlação entre os fatores de entrada (granulometria da lixa, desgaste do abrasivo, tipo do abrasivo) sobre as variáveis de saída (potência de lixamento, emissão acústica, vibração, rugosidade e integridade superficial) no processo de lixamento. O sistema desenvolvido e utilizado foi composto por uma lixadeira plana, um sistema de aquisição de dados e um sistema eletromecânico de ensaios com acionamento pneumático. Para a análise da influência da granulometria, do desgaste e do tipo do abrasivo foram utilizadas três granulometrias (80, 100 e 120 mesh), três tipos de grão abrasivos (óxido de alumínio, carbeto de silício e óxido de zircônio), três níveis de desgaste do grão abrasivo (sem desgaste, desgaste intermediário, desgaste severo) e duas espécies de madeira sendo realizadas seis repetições para cada configuração de ensaio, totalizando 324 ensaios. Os resultados foram analisados estatisticamente através de análise de variância (ANOVA) com nível de significância de 5%, acompanhado do teste de Tukey, que compara as variações aos pares. O sistema eletromecânico de ensaios de lixamento projetado mostrou-se bastante eficiente na aquisição dos dados. O desgaste do grão abrasivo influenciou significativamente ... (Resumo completo, clicar acesso eletrônico abaixo)
The sanding process is indispensable for situations where the manufacturing processes were not sufficient to ensure the final dimensions or when the desired surface quality was not achieved. This process is frequently used in panels and furniture industries, however, is almost always used empirically, without the proper knowledge. In the present study we analyzed the influence of particle size, abrasive wear and the abrasive type on Corymbia citriodora and Pinus elliottii sanding. The objective was to study and understand the correlation between the input factors (particle size, abrasive wear, abrasive type) on the output variables (power sanding, acoustic emission, vibration, roughness and surface integrity) in sanding process. The system developed and used consists of a flat sander, a data acquisition system and an electromechanical testing system with pneumatic actuation. It was used three particle sizes (80, 100 and 120 mesh), three types of grain abrasives (aluminum oxide, silicon carbide and zirconium oxide), three levels of abrasive wear (no wear, intermediate wear, severe wear) and two species of wood for the analysis, it was made six replications for each test configuration, totaling 324. The results were statistically analyzed using variance analysis (ANOVA) with a significance level of 5%, followed by the Tukey test, which compares the variations in pairs. The electromechanical testing system designed sanding proved to be very efficient in data acquisition. The abrasive wear influenced significantly roughness in both species and all abrasive grains types. The variables that wear influenced less were acoustic emission and vibration. The best values of roughness were obtained for aluminum oxide grains and the worst for silicon carbide grains. The SEM images and topography were important to understand the interaction of the abrasive grain with wood surface

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40

Varasquim, Francisco Mateus Faria de Almeida. "Efeitos da granulometria, do desgaste e do tipo de material abrasivo no lixamento plano de madeiras /". Guaratinguetá, 2014. http://hdl.handle.net/11449/111072.

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Orientador: Manoel Cleber de Sampaio Alves
Banca: Marcos Valério Ribeiro
Banca: Eduardo Carlos Bianchi
Banca: Ivaldo Domênico Valarelli
Banca: Fabio Minoru Yamaji
Resumo : O processo de lixamento é indispensável para situações onde os processos anteriores de fabricação não foram capazes de garantir as dimensões finais da peça produzida ou quando a qualidade superficial desejada não foi atingida. Este processo é muito usado em indústrias de painéis e de móveis, no entanto, quase sempre é empregado de forma empírica, sem o conhecimento adequado. No presente trabalho analisou-se a influência da granulometria, do desgaste abrasivo e do material abrasivo no lixamento plano da Corymbia citriodora e do Pinus elliottii. O objetivo do trabalho foi estudar e compreender a correlação entre os fatores de entrada (granulometria da lixa, desgaste do abrasivo, tipo do abrasivo) sobre as variáveis de saída (potência de lixamento, emissão acústica, vibração, rugosidade e integridade superficial) no processo de lixamento. O sistema desenvolvido e utilizado foi composto por uma lixadeira plana, um sistema de aquisição de dados e um sistema eletromecânico de ensaios com acionamento pneumático. Para a análise da influência da granulometria, do desgaste e do tipo do abrasivo foram utilizadas três granulometrias (80, 100 e 120 mesh), três tipos de grão abrasivos (óxido de alumínio, carbeto de silício e óxido de zircônio), três níveis de desgaste do grão abrasivo (sem desgaste, desgaste intermediário, desgaste severo) e duas espécies de madeira sendo realizadas seis repetições para cada configuração de ensaio, totalizando 324 ensaios. Os resultados foram analisados estatisticamente através de análise de variância (ANOVA) com nível de significância de 5%, acompanhado do teste de Tukey, que compara as variações aos pares. O sistema eletromecânico de ensaios de lixamento projetado mostrou-se bastante eficiente na aquisição dos dados. O desgaste do grão abrasivo influenciou significativamente ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The sanding process is indispensable for situations where the manufacturing processes were not sufficient to ensure the final dimensions or when the desired surface quality was not achieved. This process is frequently used in panels and furniture industries, however, is almost always used empirically, without the proper knowledge. In the present study we analyzed the influence of particle size, abrasive wear and the abrasive type on Corymbia citriodora and Pinus elliottii sanding. The objective was to study and understand the correlation between the input factors (particle size, abrasive wear, abrasive type) on the output variables (power sanding, acoustic emission, vibration, roughness and surface integrity) in sanding process. The system developed and used consists of a flat sander, a data acquisition system and an electromechanical testing system with pneumatic actuation. It was used three particle sizes (80, 100 and 120 mesh), three types of grain abrasives (aluminum oxide, silicon carbide and zirconium oxide), three levels of abrasive wear (no wear, intermediate wear, severe wear) and two species of wood for the analysis, it was made six replications for each test configuration, totaling 324. The results were statistically analyzed using variance analysis (ANOVA) with a significance level of 5%, followed by the Tukey test, which compares the variations in pairs. The electromechanical testing system designed sanding proved to be very efficient in data acquisition. The abrasive wear influenced significantly roughness in both species and all abrasive grains types. The variables that wear influenced less were acoustic emission and vibration. The best values of roughness were obtained for aluminum oxide grains and the worst for silicon carbide grains. The SEM images and topography were important to understand the interaction of the abrasive grain with wood surface
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41

Neves, Ana Filipa Saraiva das. "Novos compósitos abrasivos de matriz vítrea". Master's thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2247.

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O objectivo do presente trabalho é o desenvolvimento de novos abrasivos rígidos de matriz vítrea, com temperaturas mais baixas de cozedura, aglomerando partículas abrasivas de alumina. As partículas de alumina são ligadas por uma matriz vítrea que se obtém a partir de uma mistura de materiais naturais – argila, quartzo e feldspato – e uma frita comercial. A mistura das partículas de alumina e da matriz vítrea é submetida a um processo de sinterização reactiva com temperaturas da ordem dos 1200ºC – 1300ºC, resultando um produto maioritariamente amorfo e parcialmente poroso. A principal função da matriz vítrea é manter o grão abrasivo sempre actuante durante a maquinagem, mas deve também libertar as partículas abrasivas já desgastadas, a uma taxa controlada. Através da variação da composição e da percentagem em peso das matériasprimas obtêm-se diferentes tipos de mós abrasivas para diversas funções. Neste trabalho utilizou-se o diagrama ternário SiO2-Al2O3-Na2O para se estudar as matrizes convencionais e simular as novas formulações. Várias técnicas de caracterização foram utilizadas para o estudo das matrizes e abrasivos vitrificados convencionais – DRX, ATD, ATG, SEM, FRX, análise granulométrica, análise dilatométrica, velocidade de ruptura, resistência à compressão, resistência à flexão, choque térmico, módulo de Young. As técnicas anteriormente descritas forneceram informações importantes para a caracterização química, térmica, microestrutural e mecânica das matrizes vítreas e respectivos abrasivos vitrificados. Os ensaios demonstraram que um dos tipos de abrasivo vitrificado, designado por AA, apresenta as melhores propriedades mecânicas, estando estas relacionadas directamente com a composição da matriz e com a composição em fases da matriz vítrea após sinterização. Projectaram-se ainda novas composições de matrizes vítreas com temperaturas mais baixas de cozedura e melhores propriedades mecânicas. ABSTRACT: The goal of the present work is the development of the new vitrified grinding wheels, with low sintering temperatures with alumina particles. The alumina abrasive particles are bonded by a vitreous matrix obtained from a mixture of common raw materials – clay, quartz, feldspar – and a commercial ground glass frit. The mixture of the alumina particles and the vitrified matrix is submitted to a reactive sintering process in the temperature range of 1200ºC - 1300ºC, leading to a mostly amorphous and partially porous material. The main function of the vitreous matrix is the holding of the abrasive grains, but, during the grinding operation, it may also provide the releasing of the worn particles at a controlled rate. Through the variation of the composition and the weight proportion of the raw materials, diferent grinding weels are obtained for each kind of process. Ternary plots - SiO2-Al2O3-Na2O - are used in the present work to study the convencional matrices and to propose new compositions. Several characterization techniques were employed for the study of conventional matirices and vitrified abrasives: XRD, ATD, ATG, SEM, XRF, granulometric analyses, dilatometric analyses, rupture speed, compressive strength, flexural strength, thermal shock, Young’s modulus. The techniques earlier discribed led to important information on the chemical, thermal, microstructural and mechanical properties of the vitrified matrices and vitrified abrasives. Tests show that one of the vitrified abrasive grades, here labelled as AA, presents the best mechanical properties, being directly related with the matrix composition and the phasic composition of the vitrified matrix. However, new vitrified matrices compositions were projected with lower sintering temperatures and better mechanical properties.

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42

SETHI, VARUN. "Effect of Aging on Abrasive Wear Resistance of Silicon Carbide Particulate Reinforced Aluminum Matrix Composite". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1191951786.

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43

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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44

Magalhães, Luciano da Rocha. "Desenvolvimento e fabricação de penetradores para avaliação da resistência ao desgaste abrasivo de polímeros protetores de risers". Universidade Federal de Uberlândia, 2013. https://repositorio.ufu.br/handle/123456789/14957.

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Deep water oil production imposes several challenges to the oil companies. One of the greatest difficulties is related to the damages that the flexible riser pipes are subjected. These pipes conduct the produced oil to the platform. They are also used to inject water in the well in order to recover its production capacity. Among the damages mentioned, its worth to mention the abrasive wear that takes place at the touchdown point (TDP). In order to reduce this tribological degradation, PU coats have been used at the TDP region. Considering the diversity of PU that can be used in this application, it is highly desired that the PU plaques quality are controlled before its installation. Based on this demand, a portable apparatus was designed and constructed in the Laboratory for Friction and Wear at the Federal University of Uberlândia to simulate the tribological interactions between the riser pipe and the sea bed. So this work aims to produce WC-Co indenter for this test apparatus. To accomplish that, the following steps were proposed: a) equipment preparation for wear tests; b) determination of test parameters (cycle number and load) through a full factorial design; c) geometric and dimensional control of the indenters before and after machining processes; d) realization of wear tests before and after machining the indenters; e) machining of indenters using honing and lapping and f) analysis of the improvements achieved on the wear results. The results obtained allowed the following conclusions: 1) the proposed machining processes and parameters for are appropriate to manufacture the indenter In accordance with their selected dimensional and geometric tolerances. Roughness values of about 2.0 μm has been reduced by at least 60%, while for values lower than 2.0 μm this reduction was at least 33%, and 2) abrasion tests using the new indenters provide more precise and reliable results.
A extração de petróleo em águas profundas impõe diversos desafios às empresas petrolíferas. Um dos principais são os danos que os dutos flexíveis, as tubulações que levam o petróleo do poço de extração até a plataforma flutuante, sofrem ao serem expostos ao hostil ambiente subaquático. Dentre estes danos, destaca-se o desgaste abrasivo na região onde o duto toca o solo marinho, chamada de touchdown point (TDP). Para prolongar a vida útil do duto e evitar vazamentos de óleo no mar, são empregados revestimentos protetores poliméricos, usualmente chamados de calhas. A partir de uma necessidade da indústria petrolífera de testar e controlar o recebimento destes revestimentos foi projetado e construído um equipamento denominado de Simulador de Interações Marítimo-Mecânicas em Calhas (SIMMC) no Laboratório de Tecnologia em Atrito e Desgaste UFU que visa à realização de testes em campo. Assim sendo, o objetivo deste trabalho foi fabricar, controlar e testar penetradores de metal duro visando à realização de ensaios de desgaste por abrasão que permitam avaliar a resistência ao desgaste abrasivo de materiais poliméricos usados na proteção de risers. Para tanto, foram propostas as seguintes etapas: a) preparação do SIMMC Portátil para realização dos ensaios de desgaste; b) determinação dos parâmetros de teste ideais para o SIMMC Portátil (número de ciclos, carga externa e velocidade de rotação) por meio de um planejamento fatorial completo; c) controle dimensional e geométrico dos penetradores antes e após a usinagem; d) realização de testes de desgaste antes e após a retífica; e) usinagem dos penetradores utilizando afiação e lapidação e f) análise da influência das melhorias trazidas por esses processos para os resultados dos testes de desgaste. Os resultados obtidos permitem concluir que: 1) os processos de usinagem propostos são adequados para fabricação dos penetradores dentro das tolerâncias dimensionais e geométricas definidas no projeto. Valores de rugosidade da ordem de 2,0 μm foram reduzidos em pelo menos 60%, enquanto que para valores menores que 2,0 μm esta redução foi pelo menos de 33% e 2) os ensaios de abrasão utilizando os penetradores fabricados fornecem resultados mais precisos e confiáveis.
Mestre em Engenharia Mecânica

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45

Lafleur, Jean-Philippe. "A study of abrasion in steel during comminution". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103656.

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Comminution is a process used in mineral processing for the size reduction of mined material, to permit effective handling, separation and recovery. The equipment used is kinetically complex, with very high-energy impacts and high forces, leading to great amounts of abrasive wear. It is desired to develop a better understanding of these processes, to both measure them and increase comminution while reducing wear. The Steel Wheel Abrasion Test is a laboratory technique used to generate controlled, abrasive three-body wear. By altering the applied force, rotational speed of the wheel and abrasive agent used in the SWAT, the wear behaviour of a material can be quantified. High-stress wear, which occurs when abrasive material is degraded during the test, can replicate the processes occurring in comminution systems. This work has found that abrasive wear will increase with increasing input energy into the tribological interaction. This wear can be linked to the energy input into the system, through the measurement of applied forces, wheel rotational speed and generated torque. This results in the development of a specific abrasion energy, EAS, which provide an energy metric for the abrasion process. Furthermore, the breakage induced in the abrasive particles can also be quantified and evaluated, generating a comminution metric, the specific comminution energy, ECS. These indices can then be linked, to develop an understanding of systems where comminution and abrasion occur concurrently.
La communition est un procédé utilisé dans l'industrie minéralurgique pour la réduction de taille d'un minerai, afin de permettre le transport, la séparation, la récupération et l'extraction de ce matériel. L'équipement utilisé pour cette tâche est complexe, soumis à des forces élevées et des impacts violents, ce qui génère une quantité importante d'usure. Une plus grande connaissance des processus de comminution et d'usure est nécessaire pour pouvoir évaluer leur amplitude, dans le but de favoriser la comminution tout en minimisant l'usure. Le test d'abrasion par roue d'acier (SWAT) est une technique de laboratoire utilisée pour générer de l'usure abrasive à trois composantes. En contrôlant la force appliquée, la vitesse de rotation de la roue et l'agent abrasif employé lors du test SWAT, il est possible d'évaluer la réponse d'une surface à l'abrasion. L'usure de haut stress, générée dans les systèmes où les agents abrasifs sont fracturés, peut répliquer les procédés présents dans l'équipement de communition. Ce projet a trouvé que l'usure abrasive augmente avec une augmentation de l'énergie investie dans l'interaction tribologique. Cette usure peut être liée à l'énergie du système, en mesurant les forces appliquées, la vitesse de rotation de la roue et la torsion générée. Ces valeurs peuvent être utilisées pour calculer une valeur spécifique d'énergie d'abrasion, EAS, qui agit comme indice pour le procédé d'abrasion. De plus, la fragmentation créée dans les particules abrasives peut être évaluée, pour générer un indice de communition, ECS, l'énergie spécifique de communition. Ces deux indices peuvent être liés, pour rejoindre les procédés de communition et d'abrasion.

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46

Wu, Guangchang. "The mechanisms of rubber abrasion". Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25986.

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Rubber abrasion is one of the most important properties for rubber products, such as tyres. However, due to its complexity rubber abrasion is still a very challenging topic in rubber research. Rubber abrasion is not governed by a single mechanism. Different mechanisms can dominate the abrasion behaviour depending on the rubber compound, base polymer type, loading severity, contact conditions, testing temperature and chemical environment. This study investigates the different mechanisms for rubber abrasion and the transition between these mechanisms using two types of abrasion apparatus, a blade abrader and a surface abrader, respectively. Blade abrasion was used to generate the abrasion pattern. Once the abrasion pattern was formed on the rubber surface under unidirectional sliding, the underlying mechanism was primarily one of fatigue crack growth, which is referred as "fatigue wear" in the literature. An independent pure shear fatigue test with various loading profiles was conducted to predict the crack growth rate using a fracture mechanics approach during these abrasion tests. The tearing energy during blade abrasion was calculated using a fracture mechanics approach. A Finite Element Analysis (FEA) technique using the Virtual Crack Closure Technique (VCCT) was adopted. The VCCT approach was a simpler, faster and more reliable approach to derive the tearing energy under these complicated large strain contact conditions. The prediction of the abrasion rate using this independent measurement of the crack growth resistance of materials worked best for unfilled SBR material. A bespoke surface contact abrasion machine was used to investigate rubber abrasion on silicon carbide sandpaper under both dry and wet conditions. Depending on the materials, contact conditions and sliding velocity, two different mechanisms were observed. The first being a mechanochemical degradation, during which a sticky layer was generated on the rubber surface. This behaviour is also called "smearing wear". The second failure mode resulted from a purely mechanical fracture named "abrasive wear". It seemed that the carbon black filled rubber was more susceptible to smearing wear than the silica filled one. Higher sliding velocities promoted smearing wear, possibly due to higher temperatures being generated at the interface. Alternatively, water lubrication was seen to promote abrasive wear. Therefore, the abrasion mechanism changed to more rapid abrasive wear under wet conditions, which resulted in a significant increase in the rate of weight loss. Finally, the sticky debris generated during the smearing wear was characterised using various different techniques. This revealed that the sticky debris had more oxygen and lower carbon and sulphur content. It contained a greater amount volatiles and generated more char formation during its degradation in the air. The molecular weight of the sticky debris was much lower when compared to the original uncured rubber. It seemed that in the sticky debris the filler network can slowly recover and the degraded polymer chains can re-absorb back onto filler surface forming "bound rubber", which leads to faster rates of weight loss.

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47

Deus, Gustavo Portela de. "An?lise e avalia??o dos elementos de penetra??o no solo de equipamentos rodovi?rios ap?s revestimento". Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12675.

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Made available in DSpace on 2014-12-17T14:06:50Z (GMT). No. of bitstreams: 1 GustavoPD.pdf: 1290134 bytes, checksum: a233e53c4a04f17b6a39b7b4ef196218 (MD5) Previous issue date: 2008-08-22
The main objective is to analyze the abrasive wear resistance to the low stress of the elements that make up the organs of road machinery that are exposed directly to contact with abrasives. These samples were analyzed after these elements are coated superficially by the process of welding electrode coated with (SAER) and the manual process of coating type LVOF thermal spraying. As well, is to provide suggestions for a better recovery and return of these elements, which are reducing costs and avoiding downtime in the fronts of service. The samples were made from a substrate of carbon ABNT 1045 tempered steel, following the same specifications and composition of metals and alloys of constituents was followed the standard governing the dimensions of these samples and in accordance with the corresponding size. The results were evaluated by testing the hardness, abrasion resistance to wear by the low stress and the loss of volume involving the microstructure of coatings analyzed
O objetivo principal do trabalho ? analisar a resist?ncia ao desgaste abrasivo ? baixa tens?o dos elementos que comp?em os ?rg?os de m?quinas rodovi?rias que est?o expostos diretamente ao contato com abrasivos. Estas an?lises foram efetuadas ap?s estes elementos serem revestidos superficialmente pelo processo de soldagem com eletrodo revestido (SAER) manual e pelo processo de revestimento por aspers?o t?rmica tipo LVOF. Como tamb?m visa apresentar sugest?es para um melhor aproveitamento e rendimento destes elementos, quais sejam, diminuindo custos e evitando paralisa??es nas frentes de servi?o. Os corpos-de-prova foram confeccionados a partir de um substrato de a?o carbono ABNT 1045 temperado, seguindo as mesmas especifica??es e composi??es dos metais constituintes das ligas e foi seguida a norma que regulamenta as dimens?es destas amostras e de acordo com a grandeza correspondente. Os resultados foram avaliados por meio de ensaios de dureza, resist?ncia ao desgaste por abras?o ? baixa tens?o e pela perda de volume associando a microestrutura dos revestimentos analisados

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48

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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49

Arnt, Angela Beatriz Coelho. "Resistência ao desgaste abrasivo de revestimentos cerâmicos aplicados por aspersão térmica". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1999. http://hdl.handle.net/10183/159066.

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Neste trabalho, a resistência ao desgaste abrasivo de revestimentos cerâmicos (AbO3, AI2O3+ TiO2 e ZrO2+ Y2O3) foi avaliada em relação a diferentes fatores operacionais aplicados com a técnica de aspersão térmica. Utilizou-se outros revestimentos de natureza cerâmica com matriz metálica (compósitos) (WC-Co(12%) e WC-Co(17%)) e metálica (liga à base de Ni-Cr-W), para fins comparativos. Foram empregadas duas técnicas distintas de aspersão térmica para a obtenção dos revestimentos: plasma spray e hipersônico. Os corpos-de-prova foram primeiramente submetidos à deposição com uma liga Ni-Cr20, com a finalidade de diminuir as tensões de natureza térmica, e após sofreram a deposição do pó cerâmico. Os revestimentos foram então submetidos a um desgaste abrasivo em um abrasímetro, que promovia 3 movimentos rotativos contra uma lixa abrasiva. Considerando todos os sistemas comparados (cerâmicos, compósitos e metálico), o que apresentou maior resistência ao desgaste abrasivo foi o WCCo (12%). Foi constatada uma correlação da porosidade com a resistência ao desgaste para os sistemas cerâmicos. Para o sistema Al2O3+ TiO2, a maior resistência ao desgaste foi apresentada pelas amostras com menor porosidade. O mesmo comportamento não foi observado com os sistemas cerâmicos com matriz metálica e metálico, onde menores resistências ao desgaste foram obtidas para revestimentos com baixas porosidades. Também o efeito das tensões produzidas durante o procedimento de aspersão térmica foi avaliado em relação à resistência ao desgaste abrasivo. Para tanto, foram variados a distância de aspersão, o tempo de pré-aquecimento do substrato e a redução da espessura da camada depositada. O sistema cerâmico AI2O3+ TiO2 teve um ganho de 46% e 61% na resistência ao desgaste, quando respectivamente aspergido sem pré-aquecimento do substrato e com redução da distância de aspersão. Com a redução da espessura da camada depositada, os sistemas cerâmicos via de regra diminuíram a resistência ao desgaste, ao passo que para o sistema WC-Co (17%), o acréscimo foi de 53%. A razão para tanto foi imputada ao alívio de tensões. Os resultados obtidos permitiram avaliar a dependência da resistência ao desgaste de materiais cerâmicos (em comparação com materiais compósitos e metálico) aspergidos termicamente com fatores microestruturais como porosidade (quantidade e tamanho de poros), presença de trincas e descontinuidade das camadas lamelares, típicas de microestruturas aspergidas termicamente.
In this work the abrasive wear resistance of ceramic coatings ((Al2O3, Al2O3+ TiO2 and ZrO2+ Y2O3) was evaluated to different operacional factors applied through thermal spray technique. Others coatings of ceramic nature were used with metallic matrix, for comparative analysis. Two different thermal spraying techniques were used to obtain the coatings: plasma spray and high velocity oxygen fuel. The specimens were first coated with an alloy NiCr2O in arder to reduce the thermal stress, and after that, they were coated with ceramic powder. The coatings were submited to abrasive wear in a wear machine adjusted to do 3 rotatives motions against an abrasive sandpaper. Considering ali systems that were compared (ceramic, metal matrix composites and metallic), the system that shown the highest abrasive wear resistance is WC-Co(12%) A correlation was found between the porosity and the wear resistance for ceramic systems was found. The highest wear resistance was found with a low levei of porosity. The same behavior was not observed to the ceramic systems with metallic matrix and metallic, where the lower wear resistances obtained for coatings without lower porosities. Also, the stress effect, generated during thermal spraying procedure, was evaluated, correlating with the abrasive wear resistance. Pre-heating time of the substrate and the coating thickness reduction were varied. The ceramic system Al2O3+ TiO2 showed an increase of wear resistance of 46% and 61%, when it was respectively sprayed without pre-heating of the substrate and with the reduction of the spray distance. The ceramic systems had their wear resistance diminished by decreasing the coating thickness, whereas for the WC-Co(17%) the wear resistance was increased by 53%. The reason of this behavior was attributed to the stress relaxation.The results obtained, allowed us to establish the resistance dependence of thermal spraying ceramic materiais with microstructural factors like porosity (quantity and poro size), presence of cracks and lamelar layers fractured, that are typical characteristcs of thermal sprayed microstructures.

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50

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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