Aerospace and aeronautics industries push forward the research to improve constantly the quality, safety, and cost of flights. The main ways of improving products are to create lighter and better components, under a highly controlled processing from the research and development to the production at a big scale.  To achieve those goals, new processes and new materials are constantly created by engineers. In this perspective, titanium alloys have been developed and studied as they provide good mechanical properties and low density. To reduce the production costs and waste due to machining, additive manufacturing has started to be implemented on the manufacturing chains. Titanium alloys seemed to react very well to additive manufacturing, but there are still some problematics that need to be answered.  The main problematic of this thesis comes from the process development cell. It has been stated that two different titanium-based alloys, Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn, showed the same behavior under additive manufacturing, which is not an evident statement. Therefore, the goal of this work will be to understand the behavior of those two alloys by simulations and use of key parameters in order to model the process in a proper and accurate way.

A capacidade de resistência à corrosão sofrida pelas próteses dentais confeccionadas com ligas metálicas é de grande importância na clínica odontológica devido à ocorrência de possíveis reações biológicas, como por exemplo, sintomas alérgicos e degradação das restaurações. Em razão da presença de fatores diversos agindo no meio oral, todo material restaurador, metálico ou não, sofre uma ação de deterioração em sua superfície, seja por variação de pH, dieta alimentar, temperatura ou mastigação. Houve evolução de novas ligas metálicas, entre elas o titânio (Ti), que apresenta propriedades físicas e biocompatíveis excelentes, sendo um material muito utilizado em vários setores relacionados à área odontológica, principalmente na indústria de implantes dentais. Nesse estudo foi avaliada a rugosidade superficial de duas ligas metálicas (Ti e Ni Cr ) em três fases distintas, através de leituras realizadas pelo rugosímetro de superfície nos corpos de prova, submetidos à ciclagem térmica e submersos em saliva artificial à temperatura constante de 37 graus centígrados, por um período de 8 meses. Através dos resultados estatísticos obtidos, conclui-se que não existe diferença entre as ligas, no tocante aos fatores tempo e aspecto visual, havendo somente diferença significante entre as fases I e III do estudo. / The resistance capacity to corrosion to which the dental prosthesis made in mettalic alloys are subject has a major importance in the dental clinic, due to the occurance of possible biological reactions such as, for example, allergic symptoms and degradation of restorations. As there are several factors acting in the oral medium, every restoration material, either metallic or not, is subject to a deterioration action in its surface, caused by pH variation, alimentary diet, temperature and chewing. New metallic alloys have been developed, among them the Titanium (Ti), which presents excellent acceptance in the dentistry area , mainly in the industry of dental implants. This study appraised the superficial rugosity of two metallic alloys Titanium e Nickel Chromium (Ni Cr) in three different phases , through readings made by the surface rugosimeter in the test bodies, submitted to thermal cycling and submerged in artificial saliva at constant temperature of 37 degrees, for a period of 8 months. Through the achieved statistic results, it may be concluded that there is no difference between the alloys, concerning the time and visual aspect factors, there being a significant difference only between phases I and III of the study.

To test nanosize surface patterning for application as implant material, a suitable titanium composition has to be found first. Therefore we investigated the effect of surface chemistry on attachment and differentiation of osteoblast-like cells on pure titanium prepared by pulsed laser deposition (TiPLD) and different Ti alloys (Ti6Al4V, TiNb30 and TiNb13Zr13). Early attachment (30 min) and alkaline phosphatase (ALP) activity (day 5) was found to be fastest and highest, respectively, in cells grown on TiPLD and Ti6Al4V. Osteoblasts seeded on TiPLD produced most osteopontin (day 10), whereas expression of this extracellular matrix protein was an order of magnitude lower on the TiNb30 surface. In contrast, expression of the corresponding receptor, CD44, was not influenced by surface chemistry. Thus, TiPLD was used for further experiments to explore the influence of surface nanostructures on osteoblast adhesion, differentiation and orientation. By laser-induced oxidation, we produced patterns of parallel Ti oxide lines with different widths (0.2–10 μm) and distances (2–20 and 1,000 μm), but a common height of only 12 nm. These structures did not influence ALP activity (days 5–9), but had a positive effect on cell alignment. Two days after plating, the majority of the focal contacts were placed on the oxide lines. The portion of larger focal adhesions bridging two lines was inversely related to the line distance (2–20 μm). In contrast, the portion of aligned cells did not depend on the line distance. On average, 43% of the cells orientated parallel towards the lines, whereas 34% orientated vertically. In the control pattern (1,000 μm line distance), cell distribution was completely at random. Because a significant surplus of the cells preferred a parallel alignment, the nanosize difference in height between Ti surface and oxide lines may be sufficient to orientate the cells by contact guiding. However, gradients in electrostatic potential and surface charge density at the Ti/Ti oxide interface may additionally influence focal contact formation and cell guidance. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Orientador: Vicente Afonso Ventrella / Resumo: O trabalho consiste em um estudo da soldagem sobre uma placa da liga de titânio ASTM (Ti-6Al-4V) de espessura 1,44 mm, utilizando o processo de soldagem à laser Nd:YAG na condição autógena, realizando alterações de parâmetros no processo de soldagem afim de alterar o aporte térmico, encontrando propriedades características como a dureza, tensão de escoamento e microestrutura do material. Os ensaios realizados para a pesquisa foram: análise macrográfica, ensaio de tração, ensaio de microdureza e caracterização microestrutural. Para revelação dos detalhes no metal de solda, foi utilizado um ataque químico com o reagente Kroll. As medidas de geometria (largura e profundidade de penetração) dos cordões de solda, assim como a presença de descontinuidades, foram realizadas através de imagens obtidas pelo microscópio estéreo Zeiss Discovery.V8. O processamento e medição das imagens foi realizado através do software "AxioVision", um software associado ao microscópio utilizado. A análise da microestrutura foi realizada através do Microscópio Óptico Neophot 21, já o ensaio de tração foi realizado através de uma Máquina Universal de Ensaios, além do ensaio de microdureza, que foi realizado na escala Vickers. As análises das propriedades mecânicas foram confrontadas com a microestrutura obtida de acordo com a variação do aporte térmico. Como resultados, foram encontradas várias características essenciais para uma boa soldagem da liga, pois a cada incremento de aporte térmico, o cordão de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The work consists of a study of the welding on a plate of titanium alloy ASTM (Ti-6Al-4V) of thickness 1.44 mm, using the welding process Nd: YAG in the autogenous condition, making changes of parameters in the process of welding in order to change the thermal input, finding characteristic properties such as hardness, yield stress and microstructure of the material. The tests carried out for the research were: macrographic analysis, tensile test, microhardness test and microstructural characterization. To reveal the details in the weld metal, a chemical attack was used with the Kroll reagent. The measurements of the geometry (width and depth of penetration) of the weld beads, as well as the presence of discontinuities, were made through images obtained by the stereo microscope Zeiss Discovery.V8. The images were processed and measured using the "AxioVision" software, a software associated with the microscope used. The analysis of the microstructure was performed through the Optical Microscope Neophot 21, and the tensile test was performed through a Universal Testing Machine, in addition to the microhardness test, which was performed on the Vickers scale. The analysis of the mechanical properties were compared with the microstructure obtained according to the variation of the thermal input. As a result, several essential characteristics have been found for a good welding of the alloy, because with each increment of thermal input, the weld bead increases in width, depth and har... (Complete abstract click electronic access below) / Mestre

Submitted by Juliano Torteli De Godoi Zucato (jtgzucato@gmail.com) on 2018-08-15T17:17:02Z No. of bitstreams: 1 Dissertação Juliano Zucato.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-08-15T20:07:28Z (GMT) No. of bitstreams: 1 zucato_jtg_me_ilha.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) / Made available in DSpace on 2018-08-15T20:07:28Z (GMT). No. of bitstreams: 1 zucato_jtg_me_ilha.pdf: 6062254 bytes, checksum: c2ecd162aff92215ef89a486bafa836f (MD5) Previous issue date: 2018-07-03 / O trabalho consiste em um estudo da soldagem sobre uma placa da liga de titânio ASTM (Ti-6Al-4V) de espessura 1,44 mm, utilizando o processo de soldagem à laser Nd:YAG na condição autógena, realizando alterações de parâmetros no processo de soldagem afim de alterar o aporte térmico, encontrando propriedades características como a dureza, tensão de escoamento e microestrutura do material. Os ensaios realizados para a pesquisa foram: análise macrográfica, ensaio de tração, ensaio de microdureza e caracterização microestrutural. Para revelação dos detalhes no metal de solda, foi utilizado um ataque químico com o reagente Kroll. As medidas de geometria (largura e profundidade de penetração) dos cordões de solda, assim como a presença de descontinuidades, foram realizadas através de imagens obtidas pelo microscópio estéreo Zeiss Discovery.V8. O processamento e medição das imagens foi realizado através do software "AxioVision", um software associado ao microscópio utilizado. A análise da microestrutura foi realizada através do Microscópio Óptico Neophot 21, já o ensaio de tração foi realizado através de uma Máquina Universal de Ensaios, além do ensaio de microdureza, que foi realizado na escala Vickers. As análises das propriedades mecânicas foram confrontadas com a microestrutura obtida de acordo com a variação do aporte térmico. Como resultados, foram encontradas várias características essenciais para uma boa soldagem da liga, pois a cada incremento de aporte térmico, o cordão de solda aumenta em largura, profundidade e dureza, porém isto tem vantagem até determinado valor, pois conforme há o aumento do aporte térmico, a soldagem se fragiliza, pelo fato de existir vaporização do material e inclusão de poros na zona fundida. / The work consists of a study of the welding on a plate of titanium alloy ASTM (Ti-6Al-4V) of thickness 1.44 mm, using the welding process Nd: YAG in the autogenous condition, making changes of parameters in the process of welding in order to change the thermal input, finding characteristic properties such as hardness, yield stress and microstructure of the material. The tests carried out for the research were: macrographic analysis, tensile test, microhardness test and microstructural characterization. To reveal the details in the weld metal, a chemical attack was used with the Kroll reagent. The measurements of the geometry (width and depth of penetration) of the weld beads, as well as the presence of discontinuities, were made through images obtained by the stereo microscope Zeiss Discovery.V8. The images were processed and measured using the "AxioVision" software, a software associated with the microscope used. The analysis of the microstructure was performed through the Optical Microscope Neophot 21, and the tensile test was performed through a Universal Testing Machine, in addition to the microhardness test, which was performed on the Vickers scale. The analysis of the mechanical properties were compared with the microstructure obtained according to the variation of the thermal input. As a result, several essential characteristics have been found for a good welding of the alloy, because with each increment of thermal input, the weld bead increases in width, depth and hardness, however this has advantage until a certain value, since as there is increase of the contribution thermal, welding becomes fragile, due to the fact that there is vaporization of the material and inclusion of pores in the molten zone.

Titanium is one of fourth most abundant structural metal in earths soil. It is in a composition with other elements, forming titanium alloys. These alloys are used in many different areas, such as medical, energy and sports, but is most commonly used in aerospace applications. Titanium alloys have different solid phases, α, α+β and β depending on temperature and the amount of α and β-stabilizers.When machining titanium alloys, one of the most important factors to control is the temperature in the cutting zone. The built-up heat in the cutting edge of the tool, are connected to titanium alloys low thermal conductivity and high heat capacity, which means that the alloy has low heat conduction from the cutting zone. The temperature is strongly depending on the cutting speed, which is the relative speed difference between the cutting tool and the workpiece. Many studies and research work have been conducted surrounding this fact, focusing on the physical and chemical quantities, to model tool wear progression and how this affects the tool life and the metal removal. These models are often implemented and analyzed in finite element software providing detailed but time-consuming solutions.The focus for this work have been on developing a suitable tool life expectancy model, using design of experiments in combination with metamodeling to establish a model connecting cutting parameters and measured responses in terms of tool life, from a conducted milling experiment. This models where supposed to provide a platform for customer recommendation and cutting data optimization to secure reliable machining operations. The study was limited to focus on the common α+β titanium alloy 6Al-4V. The outcome and conclusion for this study, is that the tool life is strongly connected to the choice of cutting speed and the radial width of cut and that these parameters can be predicted by the two models that have been develop in this project. The models ensure the highest possible metal removal rate, to selected parameters.

A capacidade de resistência à corrosão sofrida pelas próteses dentais confeccionadas com ligas metálicas é de grande importância na clínica odontológica devido à ocorrência de possíveis reações biológicas, como por exemplo, sintomas alérgicos e degradação das restaurações. Em razão da presença de fatores diversos agindo no meio oral, todo material restaurador, metálico ou não, sofre uma ação de deterioração em sua superfície, seja por variação de pH, dieta alimentar, temperatura ou mastigação. Houve evolução de novas ligas metálicas, entre elas o titânio (Ti), que apresenta propriedades físicas e biocompatíveis excelentes, sendo um material muito utilizado em vários setores relacionados à área odontológica, principalmente na indústria de implantes dentais. Nesse estudo foi avaliada a rugosidade superficial de duas ligas metálicas (Ti e Ni Cr ) em três fases distintas, através de leituras realizadas pelo rugosímetro de superfície nos corpos de prova, submetidos à ciclagem térmica e submersos em saliva artificial à temperatura constante de 37 graus centígrados, por um período de 8 meses. Através dos resultados estatísticos obtidos, conclui-se que não existe diferença entre as ligas, no tocante aos fatores tempo e aspecto visual, havendo somente diferença significante entre as fases I e III do estudo. / The resistance capacity to corrosion to which the dental prosthesis made in mettalic alloys are subject has a major importance in the dental clinic, due to the occurance of possible biological reactions such as, for example, allergic symptoms and degradation of restorations. As there are several factors acting in the oral medium, every restoration material, either metallic or not, is subject to a deterioration action in its surface, caused by pH variation, alimentary diet, temperature and chewing. New metallic alloys have been developed, among them the Titanium (Ti), which presents excellent acceptance in the dentistry area , mainly in the industry of dental implants. This study appraised the superficial rugosity of two metallic alloys Titanium e Nickel Chromium (Ni Cr) in three different phases , through readings made by the surface rugosimeter in the test bodies, submitted to thermal cycling and submerged in artificial saliva at constant temperature of 37 degrees, for a period of 8 months. Through the achieved statistic results, it may be concluded that there is no difference between the alloys, concerning the time and visual aspect factors, there being a significant difference only between phases I and III of the study.

Orientadores: Rubens Caram Junior, Adelino Aguiar Coelho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-08T17:54:45Z (GMT). No. of bitstreams: 1 Andrade_ProtasioNery_M.pdf: 9178937 bytes, checksum: f63ed0f47d8aa70b2d3a755e537fbe8f (MD5) Previous issue date: 2006 / Resumo: Em função de características como alta razão resistência/peso, ótima biocompatibilidade, elevada resistência à corrosão e módulo de elasticidade que pode ser controlado pela adição de elementos de liga, o uso de ligas de titânio pela indústria médica e odontológica está em franco crescimento. No presente estudo, ligas do sistema Ti-Cu com teores entre 5 e 15 % em peso de cobre foram fundidas através do processo de fundição por centrifugação em moldes de cobre. A alta taxa de resfriamento imposta pelo molde empregado levou à formação de microestruturas totalmente martensítica. Em seguida, tais microestruturas foram modificadas através tratamentos térmicos, levando a estruturas mais estáveis. A caracterização das amostras obtidas envolveu análise microestrutural através de microscopia óptica e eletrônica de varredura, difração de raios-X, ensaios mecânicos. Os resultados obtidos indicam que as altas taxas de resfriamento envolvidas promoveram a formação da estrutura metaestável _'. O aumento da concentração de cobre levou ao aumento na dureza promovida pela formação do intermetálico Ti2Cu. O Ti2Cu apresentou módulo de elasticidade menor do que a fase _. A fratura dos corpos de prova teve caráter dúctil e é intensamente afetada pela presença de porosidade / Abstract: Due to characteristics like high strength-to-weight ratio, high biocompatibility, enhanced corrosion resistance and the possibility of controlling elastic behavior by proper addition of alloying elements, the use of titanium by medical and dental industries is continuously growing. In this work, Ti-Cu alloys with a Cu content varying from 5% to 15 wt% were prepared by arc melting and cast in copper molds. The high cooling rate imposed by copper mold led to the formation of a completely martensitic structure. Following, the microstructure of these samples were modified by applying proper heat treatments, leading to more stable microstructures. The samples characterization includes microstructure analyzes through optical and scanning electron microscopy, X-ray diffraction method and mechanical tests. The results obtained suggest that application of high cooling rates resulted in the formation of a'metastable phase. As Cu content was increased, hardness also increased due to Ti2Cu intermetallic compound precipitation. The Ti2Cu compound was found to present lower elastic modulus than the modulus of a phase. Finally, it was found that the heat treated samples presented high ductility and their mechanical behavior is affected by porosities / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

L’objectif de ces travaux est de développer une méthodologie de génération automatique de gammes d’usinage optimises et innovantes qui permettent aux sous-traitants aéronautiques de faire face aux problématiques de productivité et de compétitivité actuelles. Dans un premier temps, un état de l’art sur les systèmes existants de génération de gammes est présenté et permet d’introduire les limites des systèmes actuels. Une méthodologie en quatre étapes est ensuite proposée, permettant à l’utilisateur d’obtenir des gammes d’usinage optimisées respectant son savoir-faire et son expérience et introduisant de l’innovation. Cette méthodologie s’appuie sur une représentation du comportement décisionnel des méthodistes dans une situation donnée ainsi que face au risque à l’industrialisation et élargit la formalisation de la performance d’une gamme en prenant en compte d’autres critères de performance autres que le temps d’usinage ou le coût global. Ainsi, un état de l’art sur les méthodes d’aide à la décision multicritère permet de sélectionner la méthode pour l’agrégation des performances par rapport à la problématique industrielle. Après une description géométrique et technologique de la pièce et la création par les méthodistes, d’opérations d’usinage élémentaires, un algorithme génétique est utilisé pour générer des gammes optimisées. Lors d’une dernière étape, la méthodologie présente les meilleures gammes générées au méthodiste et l’utilisation de la théorie du choix social lui permet de cibler les gammes les plus performantes à implanter, en intégrant un critère de risque à l’industrialisation. Cette méthodologie a été appliquée à une pièce de train d’atterrissage usinée en alliage de Titane et a permis une diminution de 25% du temps d’usinage tout en augmentant la fiabilisation. Des perspectives d’amélioration de l’outil d’aide à la décision, à diverses étapes de la méthodologie, sont enfin proposées. / The objective of this work is to develop a Computer-Aided Process Planning (CAPP) methodology to allow aeronautical subcontractors to face the current productivity and competitiveness problems. To start, a state of the art on the existing CAPP systems is presented and introduce the limits of the current systems. A four-step methodology is then proposed, allowing the user to obtain optimized machining ranges respecting his know-how and experience and introducing innovation. This methodology is based on a representation of the decision-making behavior of the process planners in a given situation as well as the risk of industrialization and broadens the formalization of the performance by taking into account performance criteria other than the machining time or cost. Thus, a state of the art on multicriteria decision-making methods helps to select the method for the aggregation of performance in relation to the industrial problem. After a geometrical and technological description of a mechanical part and the creation by the process planners of elementary machining operations, a genetic algorithm is used to generate optimized ranges. In a final step, the methodology presents the best process plans generated to the process planners and the use of the social choice theory allows to target the most efficient ones to choose, integrating a risk criterion based on tool deflection. This methodology was applied to a Titanium alloy machined landing gear part and allowed a 25% reduction in machining time while increasing reliability. Finally, prospects for improving the decision-making tool at various stages of the methodology are proposed.

Orientador: Maria Clara Filippini Ierardi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-26T21:12:43Z (GMT). No. of bitstreams: 1 Longhitano_GuilhermeArthur_2015_M.pdf: 10352364 bytes, checksum: 6157c8c85d67a80202c0078ff2bd5901 (MD5) Previous issue date: 2016 / Resumo: No presente trabalho, a liga de titânio Ti-6Al-4V, empregada em implantes ortopédicos permanentes ou temporários devido à sua biocompatibilidade, foi produzida a partir da manufatura aditiva utilizando o processo de Sinterização Direta de Metais por Laser (DMLS). O material foi submetido a diferentes tratamentos térmicos com o intuito de modificar suas propriedades mecânicas, e a acabamentos de jateamento, ataque químico e polimento eletroquímico para analisar os efeitos dos mesmos no acabamento de superfície. As modificações resultantes após os tratamentos térmicos e acabamentos de superfície foram analisadas por microscopia óptica, microscopia eletrônica de varredura, difração de raios-X, medidas de rugosidade e massa, microdureza Vickers, e ensaios de tração e compressão. No estudo de acabamentos de superfície, o menor valor de rugosidade foi obtido após as etapas de jateamento e ataque químico combinadas. O acabamento de jateamento é responsável por deixar uma superfície com rugosidade uniforme, enquanto o ataque químico é responsável pela limpeza da superfície e redução da rugosidade. As amostras foram submetidas aos tratamentos térmicos nas temperaturas de 850 ºC, 950 ºC e 1050 ºC durante uma hora com resfriamento em forno. Foi constatado que quanto maior a temperatura empregada, maior é a ductilidade do material e, por outro lado, menor é a resistência mecânica. Tal fato ocorreu devido à maior nucleação e crescimento da fases 'alfa' e 'beta' no material, que apresentava inicialmente uma estrutura constituída por martensita hexagonal ('alfa'). A condição de tratamento térmico a 950 ºC foi a que apresentou a melhor relação de propriedades mecânicas, satisfazendo os requerimentos da norma ASTM F136 para a utilização da liga Ti-6Al-4V em implantes / Abstract: In this study, the Ti-6Al-4V titanium alloy, used in permanent or temporary orthopedic implants due to its biocompatibility, was produced by additive manufacturing using the Direct Metal Laser Sintering (DMLS) process. The material was subjected to different heat treatments in order to modify their mechanical properties, and to the surface finishes of blasting, chemical etching and electropolishing to analyze their effects on surface finish. The resulting changes after the heat treatments and surface finishes were analyzed by optical microscopy, scanning electron microscopy, X-ray diffraction, roughness and mass measurements, Vickers microhardness, and tensile and compression tests. In surface finishes study, the lowest roughness value was obtained after the combined steps of blasting and chemical etching. The blasting finish is responsible for leaving a surface with uniform roughness, while the chemical etching is responsible for cleaning the surface and reducing roughness. The samples were subjected to heat treatments at temperatures of 850 °C, 950 °C and 1050 °C for one hour followed by furnace cooling. It has been found that the higher the temperature employed, the higher the ductility of the material and, on the other hand, the lower the mechanical strength. This happened due to increased nucleation and growth of 'alfa' and 'beta' phases in the material, which initially had a structure made of hexagonal martensite ('alfa'). The condition of heat treatment at 950 ° C showed the best relation of mechanical properties, meeting the requirements of ASTM F136 for the use of Ti-6Al-4V alloy in implants / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica