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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Polymer derived ceramic composites as environmental barrier coatings on steel /

Torrey, Jessica D. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 127-142).
12

Buckling of graded coatings-A continuum model /

Chiu, Tz-Cheng, January 1999 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 154-162).
13

Fabrication of yttria-stabilized-zirconia (YSZ) coatings by electrophoretic deposition (EPD)

Xu, Hui January 2010 (has links)
Yttria stabilized zirconia (YSZ) coatings were produced from a YSZ suspension in acetylacetone (ACAC) using electrophoretic deposition (EPD) and then consolidated via the natural drying and isothermal sintering with the constraint of the metal substrates. Before EPD, the operational pH of the suspension was adjusted by addition of acetic acid or organic bases. The effect of suspension pH on the deposition of EPD coatings was studied with respect to the suspension stability, coating density and microstructure both for a mono-sized system and micro-nano binary systems. The constrained drying process of the deposits was examined via the measurement of the critical cracking thickness (CCT). The sinterability of coatings was evaluated by micro-hardness and microstructure. For a mono-sized (0.26μm) suspension, results showed that the zeta potential had a high positive value on both sides of the isoelectric point (IEP). This probably resulted from the adsorption of base molecules triethanolamine (TEA), detected by fourier transform infrared spectroscopy. Three alkalis with different molecular structure were compared and the effect of their molecule length on the interparticle repulsion was discussed. Accordingly, the double layer thickness of the particles can be estimated. Based on this, particle interactions were estimated for different pH suspensions. The reduced particle coagulation increased the packing density of the EPD coatings from 38 % at pH 7.4 to 53 % at pH 8.4. Therefore, subsequent sintering of coatings was promoted. After sintering at 1200 °C, coatings made in pH 8.4 suspensions obtained a much higher hardness and had fewer big pores than coatings fabricated in pH 7.4 suspensions. The CCT of the latter is slightly higher than the former which might be ascribed to its particle network structure. In a binary suspension composed of the coarse (1μm) and fine (with average size of 100 nm or 10 nm, content varied in 0-30 wt. % to the powder mixture) YSZ powders, interactions between different species can be tuned by the zeta potential of individual component. Binary particles can be well dispersed at pH 4 when both of the coarse and fine powders reached their highest zeta potentials. Heterocoagulation occurred between them to form a haloing structure with fine powders covered on the coarse particle surfaces when they exhibited zeta potentials of the opposite sign at pH 8.6. Particle interactions were estimated and the microstructures of the binary coatings were examined to discuss how the different fine particle sizes influenced the particle packing after EPD. At pH 4, there existed a “stability window” for the 10 nm fines at 10 wt. % whereas no noticeable the border of the window can be observed for 100 nm fines within the measuring range. 10 nm and 100 nm fine powders gave similar overall densities of binary EPD coatings which were independent of the fine powder content. For heterocoagulation coatings made at pH 8.6, although the adsorption of fine particles reduce the agglomeration of coarse powder, the low zeta potential of the halos led to a loose structure of the “skeleton” ( the packing of the coarse powder) in the final binary coatings. 10 nm fine powders was observed to give a higher CCT and denser particle packing than 100 nm fine powders especially in a pre-saturated heterocoagulated binary coatings at 20 wt. % fine powder content. In order to further improve the sintering of the EPD coatings at low temperature sintering, a layer of CuO was applied on the coarse powder surface. With the addition of 30 wt. % fine powders, the hardness of EPD coatings after sintering 2 hours at 1150°C increased from 6 to 61 Vickers. With the presence of CuO, the hardness values were enhanced by 2.5-4.25 times. The density measurements indicated that the CuO layer not only served as a sintering aid, the CuO layer also helped with the binary particle packing particularly in the heterocoagulation condition because of the stronger particle interactions between the fine powders and CuO modified coarse powders. It seems that CuO had no significant impact on the cracking resistance of the binary coatings during drying, however t-m phase transformation was observed during sintering possibly due to the liquid phase induce by CuO.
14

Feasibility of Ellipsometric sensor development for using during PECVD SIOx coated polymer product manufacturing : a thesis /

Helms, Daniel Lynn. Savage, Richard N. January 1900 (has links)
Thesis (M.S.)--California Polytechnic State University, 2009. / The letter x is subscripted in the title. Title from PDF title page; viewed on October 23, 2009. Major professor: Dr. Richard Savage. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Materials Engineering." "September 2009." Includes bibliographical references (p. 115-121). Also available on microfiche.
15

Laser cladding surface treatment for enhancement of mechanical properties

Yang, Wen Fu January 2003 (has links)
Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 2003 / Systematic laser cladding experiments were performed using a mixture of a Nickel base alloy powder mixed with tungsten carbide powder (percentage contents of tungsten carbide from 10% to 40%) on EN8 steel substrate with pre-placed powder method. Laser cladding of the Nickel base alloy powder + 50% tungsten carbide powder on EN9 steel substrate was performed with powder injection method as well. A Finite Element Method for calculating the surface temperature distribution was used to help prediction of temperature distribution laser cladding results. Composition of cladding materials was designed; a sticking agent was chosen for the pre-placed powder method. Clad coatings were obtained for different process parameters for laser cladding, and a detailed study of the affects of these parameters has been carried out. The characteristic microstructure and properties of the clad layers and interface were investigated by using an optical microscope, a micro hardness tester and a makeshift wear test. A comprehensive review is presented on the dilution of the coating and the typical problems experienced with the coating substrate interface. The results show that microstructure of clad layers comprise three zones: the cladding layer, bonding zone and heat-affected zone. The results showed that tungsten carbide particles increased the hardness and wear resistance as expected. Wear resistance of laser cladding coating is 3.5 times than that of substrate. The micro hardness range of the cladding layer is from RV 981.5 to RV 1187, which is 2-3 times than that of substrate. The micro hardness varies from cladding coating to transition layer then to heat affected zone and substrate along a gradient.
16

Contribuição ao estudo da influência da área de contato na aderência da interface argamassa colante-cerâmica.

Silva, Anne Caroline Melo da 09 July 2018 (has links)
Submitted by Biblioteca Central (biblioteca@unicap.br) on 2019-01-24T18:42:29Z No. of bitstreams: 2 ane_caroline_melo_silva.pdf: 4163065 bytes, checksum: c02af54b1eca2ea275982d3c4353e8a7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2019-01-24T18:42:29Z (GMT). No. of bitstreams: 2 ane_caroline_melo_silva.pdf: 4163065 bytes, checksum: c02af54b1eca2ea275982d3c4353e8a7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-07-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The detachment of ceramic tiles in buildings is a problem that still persists in several modern buildings, despite the various advances achieved in the sector of façade technology and an increasingly demanding consumer public. Such detachments may occur by adhesive rupture at the interfaces of the system or by cohesive rupture within any of its layers. Studies have shown that most ceramic façades in facades occur in the interface mortar and ceramic plaque and this is because it is the region of the most requested coating system by shear stresses. In Brazil, the most used methodology to evaluate the adhesion of ceramic coatings is the adhesion strength test to direct traction, however, such evaluation may be insufficient to verify the adhesion quality of the coatings to the substrate, since the adherence of the system is resulting not only from the tensile strength, but also from the shear bond strength and the extent of adhesion of the mortar. This dissertation aims to contribute to the study and understanding of the influence of the contact area on the adhesion of the interface between adhesive mortar and ceramic plate by means of the evaluation of the adhesion resistance from the crack propagation test in mixed mode of stress (MMF - Mixed Mode Flexure) simulates tensile and shear forces simultaneously. The systems produced in the laboratory reproduce conditions where the failure in the extension of the mortar contributes to the decrease of the resistance of adhesion. Through a universal mechanical testing machine, a punctual progressive load was applied to the 120 specimens produced in order to promote internal tensile and shear forces. The variables incorporated into the experiment were the type of mortar used, the thickness of the mortar in the specimen and the size of the glue failure induced in the set. The experimental results show that the adhesion strength at the interface between the adhesive mortar and the ceramic plate decreases as the adhesion failure increases, with a loss of adhesion of up to 44.2% and 51.4% (AC II and AC III, respectively). The adhesion strength values found by the direct drive test were 60.8% (AC II) and 58.1% (AC III) higher than the results obtained by the mechanical test in mixed mode, indicating an oversized system result of the facade cladding when the direct tensile adhesion strength was verified alone. / O descolamento de placas de revestimento em edificações é um problema que ainda persiste em várias construções modernas, apesar dos diversos avanços alcançados no setor de tecnologia de fachadas e de um público consumidor cada vez mais exigente. Tais descolamentos podem ocorrer por ruptura adesiva nas interfaces do sistema ou, ainda, por ruptura coesiva no interior de qualquer uma de suas camadas. Estudos mostraram que a maioria dos descolamentos cerâmicos em fachadas acontecem na interface argamassa colante e placa cerâmica e isso se dá em razão que é a região do sistema de revestimento mais solicitada por esforços de cisalhamento. No Brasil, a metodologia mais utilizada para avaliação da aderência de revestimentos cerâmicos é o ensaio de resistência de aderência à tração direta, contudo, tal avaliação pode ser insuficiente para constatação da qualidade da adesão dos revestimentos ao substrato, visto que a aderência do sistema é resultante não somente da resistência de aderência à tração, mas também da resistência de aderência ao cisalhamento e da extensão de aderência da argamassa. Esta dissertação objetiva contribuir para o estudo e compreensão da influência da área de contato na aderência da interface entre argamassa colante e placa cerâmica por meio da avaliação da resistência de aderência a partir do ensaio de propagação de fissura no modo misto de tensões (MMF – Mixed Mode Flexure) que simula esforços de tração e cisalhamento simultaneamente. Os sistemas produzidos em laboratório reproduzem condições onde a falha na extensão da argamassa contribui para a diminuição da resistência de aderência. Através de uma máquina de ensaios mecânicos universais, aplicou-se uma carga progressiva pontual nos 120 corpos de prova produzidos, de modo a promover esforços internos de tração e cisalhamento. As variáveis incorporadas ao experimento foram o tipo de argamassa utilizada, a espessura da argamassa no corpo de prova e o tamanho da falha de colagem induzida no conjunto. Os resultados experimentais mostram que a resistência de aderência na interface entre a argamassa colante e placa cerâmica decresce à medida que a falha na colagem aumenta, apresentando perda de aderência de até 44,2% e 51,4% (AC II e AC III, respectivamente). Os valores de resistência de aderência encontrados por meio do ensaio de tração direta são 60,8% (AC II) e 58,1% (AC III) maiores que os resultados obtidos pelo ensaio mecânico em modo misto, indicando um resultado superdimensionado do sistema de revestimento da fachada quando verificada a resistência de aderência à tração direta isoladamente.
17

Efeito da adi??o de carbonatos em formula??o de massa para revestimento cer?mico utilizando mat?rias-primas do Piau?

Soares, Roberto Arruda Lima 24 May 2010 (has links)
Made available in DSpace on 2014-12-17T14:07:03Z (GMT). No. of bitstreams: 1 RobertoALS_TESE1.pdf: 2084680 bytes, checksum: 363c20f74fc941226fbec8734689dfb7 (MD5) Previous issue date: 2010-05-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Piau? state is a major producer of traditional red ceramic burning as bricks, tiles and ceramic tiles, with its main production center located in the city of Teresina. The state has large reserves of raw materials that can be used in the ceramic coating as clays, quartz, talc and carbonates. However, in the preparation of ceramic bodies using only a mixture of clays with different characteristics. The study aims to evaluate the effect of adding two types of carbonates in the ceramic semiporous mass coating produced in Piau? and then to verify the potential use of these carbonates as supplementary raw material product manufactured or the feasibility of obtaining a ceramic plate that meets the specifications for the porous coating. For this, were characterized the ceramic Piau? coating mass, a calcitic carbonate and a dolomitic, were made in the levels of 2, 4, 8, 16, and 32%. The masses were formed by pressing and burneds in two environments: a laboratory furnace (1080?C, 1120?C, 1140?C, and 1160?C) and an industrial furnace (1140?C). Then, following tests of linear shrinkage water absorption, apparent porosity, bulk density and flexural strength. Furthermore, the fired specimens were tested for their macrostructure and microstructure. The results showed the possibility of using the carbonate in ceramic mass flooring produced in Piau?, as added in small proportions improved dimensional stability and increased mechanical strength of ceramics pieces. It also proved itself possible to produce porous coating when added in higher levels / O Estado do Piau? ? um grande produtor de cer?micas tradicionais de queima vermelha como tijolos, telhas e revestimentos cer?micos, com seu principal p?lo produtivo localizado no munic?pio de Teresina. O Estado possui grandes reservas de mat?rias-primas que podem ser utilizadas no setor cer?mico de revestimento como argilas, quartzo, talco e carbonatos. Por?m, na elabora??o das massas cer?micas se utiliza uma mistura de argilas com caracter?sticas diferentes. O presente trabalho tem como objetivo avaliar o efeito da adi??o de dois tipos de carbonatos em uma massa cer?mica de revestimento semiporoso produzido no Piau?, e assim verificar a potencialidade da utiliza??o destes carbonatos como mat?ria-prima complementar do produto fabricado ou a viabilidade de se obter uma placa cer?mica que atenda as especifica??es para o revestimento poroso. Para isso, foram caracterizadas a massa cer?mica de revestimento piauiense, um carbonato calc?tico e outro dolom?tico, ambos oriundos de jazidas localizadas pr?ximas a Teresina - PI. As adi??es na massa cer?mica de cada carbonato foram feitas nos teores de 2, 4, 8, 16 e 32%. As massas foram conformadas por prensagem e queimadas em dois ambientes: forno de laborat?rio (1080?C, 1120?C, 1140?C e 1160?C) e forno industrial (1140?C). Em seguida, realizados ensaios tecnol?gicos de perda ao fogo, retra??o linear, absor??o de ?gua, porosidade aparente, massa espec?fica aparente e resist?ncia mec?nica ? flex?o. Al?m disso, as amostras queimadas foram avaliadas em sua macroestrutura e microestrutura. Os resultados mostraram a possibilidade de se utilizar os carbonatos na massa cer?mica do revestimento produzido no Piau?, pois adicionado em pequenas propor??es melhorou a estabilidade dimensional e aumentou a resist?ncia mec?nica das pe?as cer?micas. Tamb?m se mostrou vi?vel para produ??o de revestimento poroso quando adicionado em teores mais elevados
18

Utilização de pó de exaustão de areia de fundição para oxidação eletrolítica assistida por plasma em liga de alumínio / Assessment of the viability of production of ceramic tiles from waste generated in the casting process using plasma electrolytic oxide of aluminum alloy

Souza, Carime dos Santos [UNESP] 18 July 2016 (has links)
Submitted by Carime dos Santos Souza null (carime@grad.sorocaba.unesp.br) on 2016-09-01T21:03:46Z No. of bitstreams: 1 Carime dos Santos Souza.pdf: 4545121 bytes, checksum: ba8bb6b62f91647bb17086513ef15327 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-05T17:33:08Z (GMT) No. of bitstreams: 1 souza_cs_me_bauru.pdf: 4545121 bytes, checksum: ba8bb6b62f91647bb17086513ef15327 (MD5) / Made available in DSpace on 2016-09-05T17:33:08Z (GMT). No. of bitstreams: 1 souza_cs_me_bauru.pdf: 4545121 bytes, checksum: ba8bb6b62f91647bb17086513ef15327 (MD5) Previous issue date: 2016-07-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Deutsche Forschungsgemeinschaft (DFG) / A fundição é o processo de produção de peças metálicas que consiste em despejar metal líquido em um molde com formato e medidas correspondentes aos da peça a ser fabricada. Durante a confecção dos moldes de areia é gerado pó de exaustão como resíduo desse processo. O descarte desse resíduo traz diversos danos ambientais e visando a utilização do resíduo, este trabalho propõe o seu uso para a produção de revestimentos, como filme de proteção em uma superfície de liga de alumínio, através da técnica de oxidação eletrolítica assistida por plasma (do inglês: Plasma Electrolytic Oxidation (PEO)). O PEO é um processo em que o plasma atmosférico e a eletrólise convencional são combinados para a alteração de superfícies metálicas em óxidos cerâmicos. Neste trabalho, foram obtidos recobrimentos em ligas de alumínio 5052, através da oxidação em plasma eletrolítico, utilizando solução eletrolítica preparada com pó de exaustão e água destilada nas concentrações de 5 g/L e 10 g/L. O plasma eletrolítico foi obtido aplicando-se uma diferença de potencial de 650 V, frequência de 200 Hz e utilizando tempo de deposição de 300 s, 600 s e 900 s. Foi feita a caracterização do resíduo pó de exaustão por Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva (EDS), Difração de Raios X (DRX) e Espectroscopia de Infravermelho (FTIR). Os revestimentos foram analisados por MEV/EDS, DRX, FTIR, ângulo de contato e energia de superfície, rugosidade, espessura e ensaio de desgaste por pino-sobre-disco. O pó de exaustão de areia de fundição apresentou ser composto por O, Si, Al, Fe, Mg, Ti, Na, K, Ca, nas fases quartzo (SiO2), hematita (Fe2O3), óxido de potássio (K2O), óxido de alumínio (Al2O3), óxido de sódio (Na2O2) e periclase (MgO). Os revestimentos apresentaram C, O, Mg, Al, Si, P, Ca, Fe, K, Zn, Ti, Na, Mn. Ao final das 20 semanas, foi constatado que os revestimentos se apresentaram hidrofílicos, com o ângulo de contato entre 70º a 90º. Os revestimentos tiveram maior rugosidade que o alumínio. O aumento da concentração acarretou na diminuição da rugosidade para as deposições. A concentração e o tempo influenciaram positivamente no aumento da espessura dos revestimentos. Independente da concentração da solução eletrolítica, a taxa de deposição diminui com o aumento do tempo de deposição. O ensaio de pino sobre disco mostrou que a placa de alumínio sem tratamento perde muita massa em relação ao pino que é de aço. Os revestimentos obtidos têm ganho de massa indicando serem abrasivos, retirando massa do pino. / Casting is the production process for metal parts that consists in pouring molten metal in a mold with corresponding shape and measurement of the part to be manufactured. During the manufacturing of sand molds exhaustion powder is generated as this process residue. The disposal of this waste causes lots of environmental damage . This work aims to propose the usage of this waste in the production of coating, as a protective film on an aluminum alloy surface through the use of electrolytic oxidation technique assisted by plasma (the English: Plasma Electrolytic Oxidation (PEO)). The PEO is a process in which the atmospheric plasma and conventional electrolysis are combined for the modification of metal surfaces on ceramic oxides. In this work, coatings in 5052 aluminum alloys were obtained through electrolytic oxidation in plasma using the electrolytic solution prepared with fume powder and distilled water at concentrations of 5 g / L and 10 g / L. The electrolytic plasma was obtained by applying a potential difference of 650 V, frequency 200 Hz and using a deposition time of 300 s, 600 s and 900 s. The characterization of the exhaustion dust residue was carried out through Scanning Electron Microscopy (MEV), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (DRX) and Infrared Spectroscopy (FTIR). The coatings were analyzed by MEV / EDS, DRX, FTIR, contact angle and surface energy, roughness, thickness and wear test in pin-on-disc. The exhaust powder from sand casting was composed of O, Si, Al, Fe, Mg, Ti, Na, K, Ca in the quartz layers (SiO2), hematite (Fe2O3), potassium oxide (K2O) oxide aluminum oxide (Al2O3), sodium oxide (Na2O2) and periclase (MgO). The coatings showed C, O, Mg, Al, Si, P, Ca, Fe, K, Zn, Ti, In, Mn. After of 20 weeks, it was verified that the coatings presented hydrophilic, with contact angle between 70º to 90º. The coatings surface presented higher roughness than aluminum. The increase in the concentration resulted in a decrease in the roughness for deposition. The concentration and the time had affected positively the increase in thickness of the coatings. Regardless the concentration of the electrolyte solution, the deposition rate decreases with the increase of deposition time. The pin on disk test showed that the untreated aluminum plate loses much mass in relation to the steel pin. The coatings obtained have weight gain which indicates that they are abrasive and able to remove the mass of the pin.
19

Innovative Design Concepts for Insulated Joints

Charlton, Zachary 27 November 2007 (has links)
The main goal of this research is to develop new and innovative designs for insulated rail joints for improved life cycle and higher cost effectiveness. The research focuses on using electrically insulating materials that replace the epoxy used in current bonded insulated joints. Insulated joints (commonly known as "IJ") are widely used on railways to electrically insulate rail segments from each other, while mechanically connecting them together. The electrical insulation is necessary for accommodating track signals. The mechanical strength is needed to ensure the rail and IJs are able to withstand the vertical, longitudinal, and lateral forces that commonly occur on track. Insulating materials that can replace the epoxy used in bonded insulated joints are researched. The electrical insulation properties and mechanical strength of different materials are examined to determine the suitability of different materials for use in insulated joint. The most promising materials for use are determined to be fiber reinforced polymers and ceramics. Insulated joint designs are developed to accentuate the strengths of these two materials. The Insulating Metal Composite (IMC) insulated joint design that uses ceramics is determined to be the most promising of the new designs and is pursued through prototype fabrication. This particular joint design is analyzed structurally using both closed form analysis and FEA analysis using the software package ABAQUS. Electrical analysis using PSPICE is carried out on the joint. Prototypes of several design iterations of the insulating metal composites are built and tested. A proof of concept static bending test of the insulating metal composites used to build the IMC insulated joint is performed using a Tinius Olsen compressive tester. A rolling-wheel load test is performed on a prototype IMC component installed in rail. Finally, a prototype of a complete IMC insulated joint is fabricated and installed on the FAST test track at TTCI facility in Pueblo, Colorado for field evaluation. Electrical testing using a megohmmeter is performed on a complete prototype joint. Structural analysis shows that the components used to construct the IMC insulated joint can withstand the vertical and longitudinal loads applied to them. Electrical analysis shows that the joint can provide adequate electrical insulation and provides the required dielectric strength in the AREMA Manual for Railway Engineering. The proof of concept test shows that an IMC component can withstand 100 kips of static load without damage. The rolling-wheel load test shows that the ceramic in the IMC components can withstand a large shock load and that the rail used in the IMC insulated joints can survive repeated and shock loads. The testing of the prototype joint on the FAST track, which is ongoing at this time has shown that the new joint concept is fully capable of providing adequate electrical insulation and mechanical strength throughout the expected life of IJs. / Master of Science
20

Utilização de resíduo de caulim para oxidação eletrolítica assistida por plasma de liga de alumínio / Use of kaolin residue for plasma-assisted aluminum alloy electrolytic oxidation

Pálinkás, Fabiola Bergamasco da Silva Marcondes 19 December 2017 (has links)
Submitted by Fabiola Bergamasco da Silva Marcondes Palinkás null (engcivil.fabiola@gmail.com) on 2018-01-20T21:57:52Z No. of bitstreams: 1 Dissertação FBSMPalinkas.pdf: 30628776 bytes, checksum: f8c1b28a4b9b016f0c23a2941f0d7dbd (MD5) / Approved for entry into archive by Minervina Teixeira Lopes null (vina_lopes@bauru.unesp.br) on 2018-01-22T16:03:33Z (GMT) No. of bitstreams: 1 palinkas_fbsm_me_bauru.pdf: 30566486 bytes, checksum: eabbf58b1b806dc2e9b0115168ca2889 (MD5) / Made available in DSpace on 2018-01-22T16:03:33Z (GMT). No. of bitstreams: 1 palinkas_fbsm_me_bauru.pdf: 30566486 bytes, checksum: eabbf58b1b806dc2e9b0115168ca2889 (MD5) Previous issue date: 2017-12-19 / O caulim é um mineral largamente explorado no mercado nacional e internacional para diversos fins industriais em especial para clareamento e carga de papel. O processo de beneficiamento do caulim gera 500 mil toneladas de resíduos anuais. O resíduo normalmente é disposto em pilhas à céu aberto podendo acarretar danos ambientais como a contaminação da água e do solo, além de mudança da paisagem natural. Sendo esse resíduo rico em silício e visando sua valorização, este trabalho propõe seu uso na produção de camada protetora em liga de alumínio pela técnica de oxidação eletrolítica assistida por plasma (do inglês: PEO - Plasma Electrolytic Oxidation) e avaliação das características dos revestimentos obtidos. Neste trabalho foram produzidos e caracterizados revestimentos obtidos em substratos de liga de alumínio 5052 pela técnica de PEO usando solução eletrolítica nas concentrações de 5 e 10 g/L de resíduo de caulim. Uma fonte forneceu a tensão de 650V e as deposições foram feitas em 3 diferentes tempos: 300, 600 e 900s para cada concentração. Foram feitas análises de caracterização do resíduo de caulim, do substrato de liga de alumínio e dos revestimentos produzidos utilizando: Microscopia Eletrônica de Varredura (MEV), Espectrometria de Energia Dispersiva (EDS), Difração de Raios X (DRX), Espectroscopia de Infravermelho (FTIR), Perfilometria e Molhabilidade. Também foi feita uma avaliação do desgaste mecânico dos revestimentos através do teste de pino sobre disco. O tratamento em substrato de alumínio por PEO utilizando solução eletrolítica de caulim produz um revestimento rugoso, hidrofóbico para a concentração de 5 g/L e hidrofílico para a concentração de 10 g/L, cuja morfologia se caracteriza por apresentar poros e regiões de coalescência. A composição química elementar desses revestimentos apresenta Al, Si, O e Mg, elementos presentes na liga de alumínio e na solução eletrolítica. Esses revestimentos são compostos por material cerâmico e apresentam estrutura cristalina correspondente a alumina. Para a concentração de 5 g/L de resíduo de caulim e tempo de deposição de 900 s também se forma estrutura cristalina correspondente a mulita, enquanto que para a concentração de 10 g/L resíduo de caulim e tempo de deposição de 600 s e 900 s se forma estrutura cristalina correspondente a antigorita e hidróxido de alumínio-magnésio hidratado. Os revestimentos caracterizam-se por boa estabilidade química, alta refratariedade, capacidade de suportar altas temperaturas e maior resistência ao desgaste mecânico, possibilitando o seu uso no desenvolvimento de novas tecnologias de materiais. / Kaolin is a mineral widely exploited in the national and international market for various industrial purposes especially for bleaching and paper loading. The kaolin processing process generates 500 thousand tons of annual waste. Waste is usually disposed of in open piles and can cause environmental damage such as water and soil contamination, as well as changes in the natural landscape. This work proposes its use in the production of protective layer in aluminum alloy by the technique of electrolytic oxidation assisted by plasma (known as PEO of Plasma Electrolytic Oxidation) and evaluation of the characteristics of the coatings obtained. In this work, coatings obtained on 5052 aluminum alloy substrates were produced and characterized by PEO using electrolytic solution at concentrations of 5 and 10 g / L of kaolin residue. One source provided the voltage of 650V and the depositions were made in 3 different times: 300, 600 and 900s for each concentration. The analysis of the kaolin residue, the aluminum alloy substrate and the coatings produced using: Scanning Electron Microscopy (SEM), Dispersive Energy Spectrometry (EDS), X-ray Diffraction (XRD), Infrared Spectroscopy FTIR), Profilometry and Wettability. An evaluation of the mechanical wear of the coatings was also made through the Pin to Disk Test. The treatment in aluminum substrate by PEO using electrolytic kaolin solution produces a rough, hydrophobic coating at the concentration of 5 g / L and hydrophilic at the concentration of 10 g / L, whose morphology is characterized by presenting pores and regions of coalescence. The elemental chemical composition of these coatings shows Al, Si, O and Mg, elements present in the aluminum alloy and in the electrolytic solution. This coating is composed of ceramic material and has crystalline structure corresponding to alumina. For the concentration of 5 g / l of kaolin residue and time of deposition of 900 s also forms a crystalline structure corresponding to mullite, whereas for the concentration of 10 g / L kaolin residue and deposition time of 600 if 900 s crystalline structure corresponding to antigorite and hydrated magnesium aluminum hydroxide is formed. The coating are characterized by good chemical stability, high refractoriness, ability to withstand high temperatures and greater resistance to mechanical wear, allowing their use in the development of new materials technologies.

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