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1
PAN, GUIRONG. "MORPHOLOGY AND PROPERTIES OF ANTI-CORROSION ORGANOSILANE FILMS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152291690.
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Vyas, Aniket. "Morphology and Properties of Clay/Nylon-6-Epoxy Nanocomposities Coatings and Films." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1414750283.
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Sanders, Stephen. "Praseodymium Oxide and Organic Modified Cerium Oxide Nanoparticles for Electrodeposition of Nickel-Ceramic Nanocomposites to Enhance Corrosion Protection and Mechanical Properties." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505156/.
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There is a consistent need in many industries, especially oil and gas, to develop coatings which have higher corrosion resistance and better hardness to extend the lifetime of equipment when it is exposed to hostile environments. Electrodeposition has been a favorable method in the synthesis of metal coatings because of its low cost, convenience, ability to work at low temperatures, and ability to control surface morphology and structure. The inclusion of ceramic nanoparticles in metal matrix composites has previously been investigated as a technique to not only increase the corrosion resistance of the native metal but also to improve the hardness and mechanical properties. Cerium oxide nanoparticles were modified through the grafting of organic groups with increasing hydrophobicity for use in nickel coatings on stainless steel to further improve the corrosion properties while maintaining the hardness of the nanocomposite coatings. The process of modifying the cerium oxide nanoparticles involved the use of aryl diazonium salts and resulted in multilayers forming on the surface of the nanoparticles. Praseodymium oxide nanoparticles were also investigated as additives to nickel coatings, since praseodymium oxide has not yet been studied as a possible corrosion protection enhancement in coatings. These coatings were evaluated for composition and corrosion using many different types of instrumental and electrochemical techniques. With the addition of both the modified cerium oxide nanoparticles and the praseodymium oxide nanoparticles into nickel coatings, an increase in coating hardness and corrosion resistance was observed over pure nickel, resulting in an improvement of the lifetime of these coatings.
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McClanahan, Eric Robert. "Modification and Enhancement of Epoxide Coatings via Elastomeric Polysulfides, Self-Assembled Nanophase Particles, Functional Sol-Gels, and Anti-Corrosion Additives." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1493674944922562.
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Brepohl, Danielle Cristina de Campos Silva. "Caracterização das camadas formadas no processo de galvanização à quente sobre uma chapa de aço livre intersticiais." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/567.
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A indústria automobilística, ao visar o aumento da garantia à corrosão, emprega na construção das carrocerias aços IF (intersticial free) galvanizados, já que estes atendem aos critérios de qualidade superficial, conformabilidade, soldabilidade, entre outras características requeridas. Dentro deste contexto, a resistência à corrosão de um aço livre de intersticiais (IF) com revestimento galvanizado comum (GI) e diferentes gramaturas (85 g/m2 (Z85), 100 g/m2 (Z100), 120 g/m2 (Z120), 144 g/m2 (Z144) e 180 g/m2 (Z180), fosfatizadas e com cataforese, foram avaliadas neste estudo por intermédio do ensaio de corrosão cíclica acelerado. O resultado deste ensaio mostrou que mesmo com a variação da gramatura do revestimento (GI) a resistência à corrosão foi praticamente a mesma, levando-se a hipótese que a camada intermetálica que está presente em todas as amostras independente da gramatura, pode possui uma grande influência na resistência à corrosão. Assim ensaios suplementares foram feitos para compreender o efeito da camada de zinco e a camada intermetálica na resistência à corrosão. A caracterização das camadas formadas durante o processo de galvanização GI foi realizado na amostra com gramatura de 100 g/m2 (Z100). Tal amostra foi escolhida por ser a mais empregada pela indústria automobilística e a mesma não sofreu nenhum pré tratamento já que o objetivo foi analisar apenas as camadas do galvanizado comum GI. Os ensaios realizados foram de microestrutura (XRD, MEV e EDS) e ensaio eletroquímico (dissolução eletroquímica e polarização potenciodinâmica). Concluiu-se que a camada intermetálica é formada pelas fases Fe2Al5 e FeAl3, com predominância da fase Fe2Al5. O ensaio de dissolução eletroquímica demonstrou que a resistência o corrosão da camada intermetálica é no mínimo 7 vezes maior que a do zinco, além deste resultado o ensaio de polarização potenciodinâmica apresentou que a camada intermetálica passiva, retardando a velocidade de oxidação, ou seja, aumenta a resistência à corrosão do galvanizado comum GI.The automobile industry, when seeking to increase warranty against corrosions, employs galvanized IF (intersticial free) steels to the body shell, since these meet the superficial, compliance, weldability and other quality criteria. In this context, the corrosion resistance of an IF steel with galvanic coating (GI) and different weights (85 g/m2 (Z85), 100 g/m2 (Z100), 120 g/m2 (Z120), 144 g/m2 (Z144) and 180 g/m2 (Z180), phosphated and with cataphoresis, were evaluated through an accelerated cyclical corrosion experiment. The result of this experiment showed that even with the variation of the galvanic coating (GI) the result of the corrosion resistance was the same, leading to the hypothesis that the intermetallic layer which is present in all samples, regardless of the weight, must influence corrosion resistance. Thus, supplementary experiments were done to comprehend the effect of the zinc layer and the intermetallic layer in corrosion resistance. The characterization of the layers formed in the GI galvanizing process was done in the Z100 (100g/m²) sample. This sample was chosen because it is the most used in the automobile industry and it did not suffer any previous treatment since the objective was to analyze only the layers of galvanized GI. The experiments done were in the microstructure (XRD, MEV and EDS) and electrochemical experiment (potenciodinamic polarization). We concluded that the intermetallic layer is formed by phases Fe2Al5 and FeAl3, with predominance of phase Fe2Al5. It was verified through the electrochemical dissolution experiment that the intermetallic corrosion resistance is at minimum 7 times greater than of the zinc, further on this result, the potentiodynamic polarization experiment shows that the passive intermetallic layer slows the oxidation velocity, which means, the galvanic coating (GI) corrosion resistance is increased.
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Wang, Yimin. "Pretreatment, Morphology and Properties of Organosilane Anti-Corrison Coatings." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186412600.
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Vadwlas, Shatrugna. "Effect of phase stability and segregation on the corrosion properties of Alloy-22 (UNS NO6022) in base metal and weldments." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447594.
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Miranda, Joana Maia. "Synthesis, characterization and performance evaluation of nanostructured additives with anti-corrosive properties in reinforced concrete." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22520.
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Mestrado em Engenharia QuímicaEste trabalho tem como objetivo aplicar hidróxidos duplos lamelares (LDHs) intercalados com inibidores de corrosão em betão armado por forma a proteger as estruturas de aço da corrosão e aumentar a longevidade do mesmo. Para tal, foram sintetizados LDH-NO3 e LDH-NO2. A partir da suspensão de LDH-NO3, procedeu-se à intercalação com iões citrato e tartarato. Todas as amostras foram caracterizadas utilizando técnicas como espetroscopia de FT-IR, X-RD, potencial zeta, DLS, SEM/TEM e ICP. Realizaram-se estudos de libertação, colocando, em agitação, alíquotas de soluções aquosas de cloreto de sódio (NaCl) às concentrações de 5, 50 e 500 mM com LDH em pó. Recolheram-se alíquotas durante um mês e analisaram-se as amostras por cromatografia líquida (HPLC), para determinar as concentrações dos inibidores em solução ao longo do tempo. Procedeu-se, ainda, a estudos de impedância eletroquímica para avaliação do desempenho dos materiais na prevenção do ataque corrosivo ao aço. Para tal, expôs-se uma placa de aço a suspensões de diferentes concentrações de espécie agressiva (ião cloreto) com LDHs e mediram-se os valores de impedância ao longo do tempo. Com este trabalho conseguiu-se avaliar o desempenho anticorrosivo de diferentes aniões, além dos já conhecidos, e perceber quais trariam vantagens com o seu uso. Observou-se que nas suspensões com maior concentração de espécie agressiva, a libertação de inibidor foi superior. Através dos espetros de FT-IR e imagens de SEM/TEM, depreendeu-se que a encapsulação decorreu com sucesso. Apesar de não se ter tido oportunidade de testar o desempenho dos materiais encapsulados, seria um ponto vantajoso no desenvolvimento do trabalho.
This work consisted in the preparation and characterization of layered double hydroxides (LDHs) intercalated with corrosion inhibitors with the purpose of including them in concrete, to protect steel from corrosion and increase concrete’s longevity. LDH-NO3 and LDH-NO2 were synthesized and, using, LDH-NO3 suspension, intercalation with citrate and tartrate ions was performed. All samples were characterized using FT-IR spectroscopy, X-RD, Zeta potential measurements, DLS, SEM/TEM and ICP. Release studies were performed, mixing NaCl solution at different concentrations (5, 50, 500 mM) with each LDH sample. Several aliquots were collected over a month and analysed by HPLC to determine the concentration of inhibitors released over time. Electrochemical impedance studies were performed to evaluate the performance of LDHs intercalated with inhibitors against steel corrosion. Thus, a carbon steel board was exposed to a suspension with the aggressive specie (chloride ion) at different concentrations and LDHs. Impedance data was collected over time. Therefore, it was possible to analyse the pertinence of the inclusion of the tested materials into concrete’s mixture, when comparing their action against the corrosive process. It was verified that for suspensions with higher concentrations in aggressive specie, the release of the inhibitor was superior. Through FT-IR spectra and SEM/TEM images, it was concluded that the encapsulation occurred successfully. Even though the performance of the functionalized materials was not tested, it would be advantageous for the on-going development of the work.
9
Esenham, E. V. "Properties of electrodeposition paints related to some resin parameters; changes caused by altering acid values and molecular weights of resins in electrophoresis and endosmosis during deposition : Ionic permeability and inhibition in service, of anti-cor." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371490.
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Chen, Guan-Hao, and 陳冠豪. "Anti-Corrosion Properties of Waterborne Polyurethane Modified with Aminopropyl Trimethoxysilane." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/hgs85m.
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碩士義守大學
化學工程學系暨生物技術與化學工程研究所
102
This research focused on anti-corrosion behaviors of water-borne polyurethane (WPU)-based emulsions. Electrochemical tests were employed to evaluate the effect of additives such as a crosslinking agent, hexamethoxymethyl melamine (HMMM), and a silane coupling agent, aminopropyl trimethoxysilane (APTMS). The emulsions were used to fabricate membranes or were coated on galvinzed steel sheets, and a series of experiments were conducted. The experimental results for the systems of WPU/APTMS and WPU/APTMS/HMMM showed that gel content increased with increasing HMMM dosage. The increase in crosslink density also led to a decrease in water uptake. Contact angle values also increased with increasing HMMM dosage, too. Tape tests were employed to assess the adhesion of the coated films to the metallic substrate and they showed the adhesion improved with the use of APTMS and HMMM. The aqueous copper sulfate solution drop test result also showed that an increase in crosslink density led to a better water barrier property. The electrochemical tests showed that the addtion of APTMS and HMMM had a positive effect on the anti-corrosion performance of the steel sheets.
11
Lin, Yi-Wei, and 林逸瑋. "Corrosion properties of stainless steels and anti-corrosive high-entropy alloys." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/63676880818403269759.
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Yu, Yuan-Fu, and 游源福. "Preparation and Anti-Corrosion Properties Studies of Polyaniline/Aluminum Oxide Nanocomposite Materials." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/62676299328797553402.
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碩士華梵大學
機電工程學系博碩專班
98
ABSTRACT In this research, a series of polyaniline(PANI)/aluminum oxide nanocomposite materials have been successfully synthesized and characterized by Fourier-Transformation infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM). The anti-corrosion properties of as-prepared nanocomposite materials were also tested by electrochemical analyzer. Well-dispersed nano aluminum oxide was observed by the TEM analyses of the nanocomposite material containing 3 wt. % of aluminum oxide, in form of film. PANI/aluminum oxide nanocomposite materials, in form of coating, incorporating with low loading (e.g., < 5 wt. %) of nano aluminum oxide (e.g., 10~20 nm) on cold rolled carbon steel, SPCC, were found much superior in corrosion protection over those of neat PANI base on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and alternative current impedance analysis in 5 wt. % aqueous NaCl electrolyte. As the loading of nano aluminum oxide increased, the corrosion potential shifts to a higher potential, the polarization resistance shifts to a higher resistance and the corrosion current shifts to a lower current, indicating anti-corrosion properties were improved. As the results of alternating current impedance, the impedance of polymer membrane was effectively increased by the addition of nanao aluminum oxide. Moreover, it showed more obviously increasing along with the loading content of nano aluminum oxide. This might probably leaded to the significant reducing in corrosion rate on the surface of metal.
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Moyo, Fortunate. "Using ruthenium to modify surface properties of austenitic stainless steel for improved corrosion resistance." Thesis, 2017. https://hdl.handle.net/10539/25540.
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A thesis submitted to the Faculty of Engineering and the Built Environment, University of Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy (Engineering), 2017Chromium oxide provides an inexpensive and practical means of increasing the corrosion resistance of austenitic stainless steel in most environments. However, the oxide is prone to dissolve in reducing acids and in chloride containing solutions, which compromises the durability and effective operation of structures made of austenitic stainless steel. This research project explored the use of thin ruthenium surface alloys produced by ion implantation, RF sputtering and pulsed electrodeposition (PED) to improve the corrosion resistance of AISI 304L austenitic stainless steel in reducing acids and chloride solutions via a technique known as cathodic modification. The properties of the alloyed 304L stainless steel were evaluated using a number of tools including X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), potentiodynamic polarisation, and electrochemical impedance spectroscopy (EIS). Preliminary tests in 1 M sulphuric acid showed that the ruthenium surface alloys sufficiently raised the corrosion potential of 304L stainless steel to ranges where the stability of chromium oxide is guaranteed. Surface alloys produced by RF sputtering and PED were associated with the best corrosion resistance, and protection efficiencies of at least 85%, but they spalled during corrosion exposure rendering them unsuitable for corrosion application. The corrosion of the ruthenium implanted surface alloys exhibited a strong dependence on the surface roughness of the stainless steel, with the least corrosion rates achieved on rough 304L stainless steel samples implanted with 1016 Ru/cm2 at 50 keV. Corrosion characterisation of these ruthenium implanted surface alloys was studied in various corrosive media including sulphuric acid, sodium chloride, magnesium chloride and simulated fuel cell solutions. Their corrosion rates in sulphuric acid decreased with increase in acid concentration, and exhibited non-Arrhenius behaviour in the acid solutions; corrosion rates were unaffected by increasing exposure temperature from 25 to 50°C. In 3.5 wt% sodium chloride, addition of ruthenium via ion implantation changed pit morphology from elongated to circular, indicating a diminished tendency for pits to initiate at manganese sulphide stringers. Corrosion rates of the ruthenium implanted stainless steels in the simulated fuel cell solutions were at least 69% lower than the target corrosion rate for use in polymer electrode membrane fuel cells (PEMFCs), thus presenting a possible practical application of ruthenium surface alloyed austenitic stainless steel.
CK2018
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Chen, Shoou-yih. "Comparison of fatigue, corrosion And corrosion fatigue properties of 3cr12, corten and mild steel in air and polythionic acid solution." Thesis, 1991. http://hdl.handle.net/10539/22413.
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A dissertation submitted to the faculty of engineering, University of the Witwatersrand, Johannesburg in fulfillment of the requirements for the degree of master of scienceSteel 3CR12 is a 12 chromium, titanium stabilized, corrosion resisting steel which was developed in South Africa in the recent past (Abbreviation abstract)
AC2017
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Li, Chen-En, and 李晨恩. "Preparation and Anti-Corrosion Protection Properties of Transparent Polyimide and Polyaniline/ Alumina Nanoplatelets Composite Film." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/32902227815302083853.
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碩士國立勤益科技大學
化工與材料工程系
103
Thus, the present paper-based selection of Alumina nanoplatelets ( Alnp ) and added to the polymer polyimide and polyaniline, and focuses on the Nanocomposites of Polymer anti-corrosion properties, hoping to apply to flexible panels. The Alnp was prepared by hydrothermal system. The function groups on the graphene oxide (GO) will react with aluminum isopropoxide ( AlIP ), then Alnp will form on the GO. After high temperature process, the GO will decompose to get the Alnp. The characterization and structure of Alnp will be confirmed by TGA, SEM, TEM and EDS. The results of TGA reveal that weight loss at 350 and 600 ℃ were the precursor transfer into the Alnp. The morphology of SEM and TEM exhibit the nanosheets of alumina. The document that graphene and clay add a sheet of material in a polymer in an effective way to extend the gas penetration, and thus enhance the water vapor barrier properties, with polyaniline anti-corrosion properties. Therefore, this study synthesis of Alnp, individual added Polyimide ( PI ) and Polyaniline ( PANI ) prepared the nano composite via experimental study its anti-corrosion effect.
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Huang-MingWu and 吳桓銘. "Tribological and anti-corrosion properties of high temperature heat treated carbon content high entropy alloys which apply to anti-stick glass mold." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/348wm2.
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Lekala, Makgale Barclays. "Corrosion and other properties comparison of AISI 316L stainless steel surface alloyed with Ru/Ni mixtures with the parent metal and with Hastelloy© C-276." Thesis, 2016. http://hdl.handle.net/10539/22598.
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A dissertation submitted to
the University of the Witwatersrand
in fulfilment of the requirements for the degree of
Master of Science in Engineering
(Metallurgy & Materials)
2016The surfaces of AISI 316L stainless steel plate were laser alloyed with ruthenium powder as well as a mixture of ruthenium and nickel powders using a Nd:YAG laser set at fixed operating parameters. The microstructure, elemental composition, and corrosion characteristics of the alloyed zone were analysed using optical and scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and corrosion potential measurements. EDS analysis of the alloyed specimen showed that through the laser surface alloying, 2 mm surface layers with 12.5wt % Ru and 5.2wt% Ru were produced on an AISI 316L stainless steel. Similar microstructures which were dendritic and columnar grains, typical of weld beads under non-equilibrium cooling conditions were observed for all samples. Hardness profile measurements showed a significant increase from 160 HV for the substrate to a maximum of 247 HV for the alloyed layer. Using an Autolab potentiostat, the corrosion behaviour and resistance of the laser alloyed layers, substrate AISI 316L, and Hastelloy© C-276 were evaluated and compared in sulphuric acid solution of different concentration and temperatures. The Hastelloy© C-276, followed by the 12.5wt% Ru presented the most noble corrosion potential (Ecorr) and the lowest corrosion current density (icorr). However, in 60wt% H2SO4 and 40oC, the 5.22 wt% Ru alloys exhibited slightly better anticorrosive properties than 12.5wt% Ru. The observed corrosion potential, Ecorr, for untreated AISI 316L stainless steel sample in 40wt% sulphuric acid solution at 40oC was -277 mV. The 5.22 wt% Ru and 12.5wt% Ru alloyed stainless steel samples presented -240 mV, and 61 mV respectively in the same solution. Besides showing comparable performance to 5.2wt%Ru sample within specific short potential ranges, Hastelloy© C-276 was generally superior in all solutions. In addition it was found that the stability of the passive layer was improved with additions of Ru. Based on the developed costing equation the cost of 5 mm AISI 316L stainless steel plate with surface area (A = 1 m2) surface alloyed with 5.2wt% Ru to a depth of 2 mm using Nd: YAG laser is estimated at R15 989, and it is less than the cost of a Hastelloy© C-276 plate of similar size which is estimated at R19 900. As the material thickness increases, the cost benefit of laser surface treatment increases and vice versa. Reduction of the Ru additions to levels below 5.2wt% would improve cost competition without detracting from performance.
MT2017
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Pereira, Joana Maria Moreira. "Evaluation of in vitro biocompatibility of functionalized magnesium alloys for application in orthopedic implants." Master's thesis, 2021. http://hdl.handle.net/10773/30695.
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Magnesium alloys have been widely studied and applied in the biomedical field,
namely in the orthopedic area, due to their promising properties. Their
biocompatibility, biodegradability, mechanical properties and osteogenic
properties allow the use of these alloys as alternatives to the currently available
materials. However, the uncontrolled corrosion and hydrogen formation in
magnesium alloys can cause serious damages when introduced into the human
body. In order to meet these challenges, different methods have been developed
to control them, such as surface pre-treatments, coatings and alloying. The
different systems produced, however, require a detailed assessment of
biocompatibility for later use in the medical field. But there is still a gap in the
assessment of biocompatibility, especially in the hemocompatibility of such
materials. This work was conducted in the scope of the MAGICOAT project and
aimed to assess the biocompatibility (cytotoxicity and hemocompatibility) of a
multilayer system composed of a Mg1Ca alloy, pre-treated with hydroxyapatite,
with a subsequent polyetherimide (PEI) coating containing calcium-loaded
gelatin microcapsules or calcium carbonate particles. As both calcium-loaded
gelatin microcapsules and calcium carbonate particles were to be included in the
PEI coating, their morphology, release profile and their cytoto xicity were
assessed prior to the biocompatibility assays of the complete system. The
complete multilayer system was initially tested for cytotoxicity, analyzing the
integrity of the cell membrane and cell proliferation, through LDH and WST-1
assays. After the results proved that the multilayer system was non-toxic,
hemocompatibility tests were carried out. In vitro tests to verify the occurrence of
hemolysis and activation of the complement system confirmed the
hemocompatibility of the system after 4 hours of contact with the blood.As ligas de magnésio têm sido amplamente estudadas e aplicadas no campo da biomedicina, nomeadamente na área ortopédica, devido às suas propriedades promissoras. A biocompatibilidade, biodegradabilidade, propriedades mecânicas e osteogénicas destas ligas, permitem o seu uso como alternativas aos materiais atualmente disponíveis. No entanto, a corrosão descontrolada e a formação de hidrogénio, nas ligas de magnésio, podem causar sérios danos quando introduzidas no corpo humano. Para enfrentar estes desafios, diferentes métodos foram desenvolvidos de forma a controlá-los, como pré-tratamentos de superfície, revestimentos e diferentes elementos de liga. Os diferentes sistemas produzidos, no entanto, requerem uma avaliação detalhada da sua biocompatibilidade para uso posterior na área médica. Porém, existe uma lacuna na avaliação da biocompatibilidade, principalmente na hemocompatibilidade destes materiais. Este trabalho foi realizado no âmbito do projeto MAGICOAT e teve como objetivo avaliar a biocompatibilidade (citotoxicidade e hemocompatibilidade) de um sistema multicamada composto por uma liga de Mg1Ca, pré-tratada com hidroxiapatite, e um revestimento, subsequente, de poliéterimida (PEI) contendo microcápsulas de gelatina com cálcio ou partículas de carbonato de cálcio. Como as microcápsulas de gelatina carregadas de cálcio e as partículas de carbonato de cálcio deveriam ser incluídas no revestimento PEI, a sua morfologia, perfil de libertação de cálcio e sua citotoxicidade foram avaliadas antes dos ensaios de biocompatibilidade do sistema completo. O sistema multicamada completo foi inicialmente testado relativamente à sua citotoxicidade, analisando-se a integridade da membrana celular e a proliferação celular, através dos ensaios de LDH e WST-1. Após os resultados comprovarem que o sistema multicamadas não era tóxico, foram realizados testes de hemocompatibilidade. Testes in vitro para verificar a ocorrência de hemólise e a ativação do sistema complemento confirmaram a hemocompatibilidade do sistema após 4 horas de contato com o sangue.
Mestrado em Materiais e Dispositivos Biomédicos
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Brandal, Grant Bjorn. "Joining and Deformation Processes with Corrosion Resistance." Thesis, 2016. https://doi.org/10.7916/D89028D8.
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Dissimilar metal joining was performed with the main goal being maximization of the strength of the joined samples, but because of some potential applications of the dissimilar joints, analyzing their corrosion behavior also becomes crucial. Starting with materials that initially have suitable corrosion resistance, ensuring that the laser processing does not diminish this property is necessary. Conversely, the laser shock peening processing was implemented with a complete focus on improving the corrosion behavior of the workpiece. Thus, many commonalities occur between these two manufacturing processes, and this thesis goes on to analyze the thermal and mechanical influence of laser processing on materials’ corrosion resistances.
Brittle intermetallic phases can form at the interfaces of dissimilar metal joints. A process called autogenous laser brazing has been explored as a method to minimize the brittle intermetallic formation and therefore increase the fracture strength of joints. In particular, joining of nickel titanium to stainless steel wires is performed with a cup/cone interfacial geometry. This geometry provides beneficial mechanical effects at the interface to increase the fracture strength and also enables high-speed rotation of the wires during irradiation, providing temperature uniformity throughout the depth of the wires. Energy dispersive X-ray spectroscopy, tensile testing, and a numerical thermal modelling are used for the analysis.
The material pair of nickel titanium and stainless steel have many applications in implantable medical devices, owing to nickel titanium’s special properties of shape memory and superelasticity. In order for an implantable medical device to be used in the body, it must be ensured that upon exposure to body fluid it does not corrode in harmful ways. The effect that laser autogenous brazing has on the biocompatibility of dissimilar joined nickel titanium to stainless steel samples is thus explored. While initially both of these materials are considered to be biocompatible on their own, the laser treatment may change much of the behavior. Thermally induced changes in the oxide layers, grain refinement, and galvanic effects all influence the biocompatibility. Nickel release rate, polarization, hemolysis, and cytotoxicity tests are used to help quantify the changes and ascertain the biocompatibility of the joints.
To directly exert a beneficial influence on materials’ corrosion properties laser shock peening (LSP) is performed, with a particular focus on the stress corrosion cracking (SCC) behavior. Resulting from the combination of an applied load on a susceptible material exposed to a corrosive environment, SCC can cause sudden material failure. Stainless steel, high strength steel, and brass are subjected to LSP and their differing corrosion responses are determined via cathodic charging, hardness, mechanical U-bend, Kelvin Probe Force Microscopy, and SEM imaging. A description accounting for the differing behavior of each material is provided as well as considerations for improving the effectiveness of the process.
SCC can occur by several different physical processes, and to fully encapsulate the ways in which LSP provides mitigation, the interaction of microstructure changes induced by LSP on SCC mechanisms is determined. Hydrogen absorbed from the corrosive environment can cause phase changes to the material. Cathodic charging and subsequent X-ray diffraction is used to analyze the phase change of sample with and without LSP processing. Lattice dislocations play an important role, and transmission electron microscopy helps to aid in the analysis. A finite element model providing spatially resolved dislocation densities from LSP processing is performed.
20
Peng, Chih-Wei, and 彭志偉. "Preparation, Characterization and Anti-corrosion as well as Sensing Properties of Biomimetic 3D-nanopatterning Super-hydrophobic Polymeric Materials and Electroactive Materials." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30731524065000574188.
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博士中原大學
化學研究所
100
In this research, a series of biomimetic 3D-nanopatterning super-hydrophobic polymeric materials and electroactive materials were prepared by different technologies. This essay is divided into two parts. In the first part, anticorrosion coating materials were prepared by replicating fresh plant leaves. Superhydrophobic polyaniline coating applied for corrosion protection was prepared and coated on the surface of cold rolled steel (CRS) using a nanocasting technique from the surface structure of fresh Xanthosoma sagittifolium leaves. First, the transparent PDMS template was replicated from the surface structure of fresh Xanthosoma sagittifolium. Subsequently, the coating was fabricated on the CRS electrode using a nanocasting technique with a transparent PDMS template and a polyaniline solution as the ink. The CRS electrode coated with super-hydrophobic surface (SHS) of polyaniline was found to exhibit a water contact angle (CA) of 156∘, which was significantly higher than the smooth polyaniline coated on the CRS by spin coating (CA = 90∘). The SHS polyaniline coating material not only shows superior water repellent properties but also electroactive properties. It should be noted that the CRS coated with SHS polyaniline was found to exhibit remarkably enhanced corrosion protection on the basis of a series of electrochemical corrosion measurements performed under saline conditions. Further, UV-curing nanocasting technique was also used to develop advanced anticorrosive coatings with bio-mimetic xanthosoma sagittifolium leaf-like, non-fluorinated, super-hydrophobic polymeric Surfaces. Epoxy-acrylate coatings with biomimetic structures can be prepared by performing the UV-radiation process upon casting UV-curable precursor with photo-initiator onto cold-rolled steel (CRS) electrode under PDMS template. Surface morphology of as-synthesized epoxy-acrylate coatings obtained from this UV-curing nanocasting technique was found to show lots of micro-scaled mastoids, each decorated with many nano-scaled wrinkles was investigated systematically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It should be noted that the water contact angle (CA) of coating with bio-mimetic natural leaf surface was ~ 151°, which was found to significantly higher than that of corresponding polymer with smooth surface (i.e., CA = 88°). Significantly increase of contact angle indicated that this bio-mimetic morphology exhibited effectively water-repelling properties, implying that it may be the potential candidate as advanced anticorrosive coating materials, which can be identified by series of electrochemical corrosion measurements. The second part, the electroactive silica fibers (ESF) based on conjugated segments of aniline pentamer (AP) were successfully prepared and characterized. First, aniline pentamers were prepared by chemical oxidative coupling reaction, followed by reacting with silane coupling agent (3 –isocyanato propyl triethoxy silane). The electrospining solution was prepared by electroactive silane and tetraethoxysilane (TEOS) through acid-catalyzed sol-gel reaction. The as-prepared electroactive silica fibers were then characterized through Fourier transform infrared spectroscopy (FTIR), liquid chromatography mass spectrometry (LC-mass), 1H-nuclear magnetic resonance (1H-NMR). The morphology of electroactive silica fibers were investigated by scanning electron microscope (SEM). Finally, the composite used to detect ascorbic acid (AA) of the biosensor by electrochemical cyclic voltammetric (CV).
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Snyman, Christo Julius. "An investigation into the forming of 3CR12 rectangular tubes." Thesis, 2012. http://hdl.handle.net/10210/6874.
Full textAbstract:
M.Ing.During all manufacturing processes it is crucial to use certain design criteria and guidelines. Special care should be exercised when the final product of a manufacturing process is used in the automotive industry, because the failure of such a component may have tragic consequences. The failure of a bus chassis in the public transport sector is an example of a case where the failure of a product can have serious consequences. In recent years it has become common practice to use corrosion-resisting steel in the manufacture of these vehicles. The reason for this is the corrosion caused by a prolonged service life and adverse conditions such as salted road surfaces (The salt is used to melt the ice that forms on roads, particularly in European countries). These bus structures consist of tubes of varying size and geometry, and the manufacturing process of these tubes is considered in the present investigation. In a tube manufacturing process the design criteria may consist of such properties as the tube size and geometry, the thickness of the sheet that is used and the radius of the corners of the tube. Design criterion is also dependent upon the material that is used. The change in mechanical properties of the material during a manufacturing process is an important consideration during the establishment of design guidelines. The purpose of this investigation is to study the effects of particularly the cold forming manufacturing process on the mechanical properties of the material. The material used is 3CR12 corrosion resisting steel, a proprietary alloy also known as Type 1.4003, that was developed by Columbus joint venture as a cheaper alternative to stainless steels. 3CR12 is not a substitute for stainless steel but it is an alternative to treated mild steel, providing a cost-effective solution to corrosion. An experimental investigation is conducted into the forming of 40mm 3CR12 square tubes and normal plate bending of 3CR12. Various different wall thicknesses and bend radiuses are considered. A numerical investigation consisted of simulating the above-mentioned manufacturing processes using non-linear finite element analysis and then comparing its results to the experimental investigation. The experimental investigation showed that substantial work hardening occurred in the corner regions of the tube during forming. A loss of up to 70% of 3CR12's ductility may result in the corner regions. The work hardening at the inside of the tube was found to be higher than at the outside. A region of very little work hardening near the middle of the tube wall thickness was also identified (neutral axis). This neutral axis also seems to shift slightly more to the inside of the tube with thicker wall sections. The numerical analysis confirmed the experimental observations. An excellent correlation between the experimental and numerical results was achieved.