Desenvolvimento e caracterização de novas ligas do sistema Ti-Ta-Zr para aplicações biomédicas
Carregando...
Arquivos
Data
2019-12-09
Autores
Kuroda, Pedro Akira Bazaglia
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Titânio e suas ligas, atualmente, são utilizados como implantes por possuírem excelente resistência à corrosão e propriedades mecânicas mais adequadas que os implantes de aço inoxidável e de Co-Cr. A liga de titânio mais utilizada para aplicações biomédicas é a liga Ti-6Al-4V, porém estudos mostraram que os elementos vanádio e alumínio são elementos nocivos à saúde humana. Assim, para contornar este problema, novas ligas de titânio sem a presença desses elementos estão sendo estudadas. O objetivo desse trabalho foi preparar ligas do sistema Ti-25Ta-Zr (onde o teor de zircônio foi variado de 0 a 75% em peso), e analisar a influência do soluto substitucional zircônio na estrutura cristalina, microestrutura, microdureza, módulo de elasticidade e biocompatibilidade das ligas. Paralelamente, diversos tratamentos de recozimento, laminação e solubilização foram realizados com o intuito de modificar as fases, microestrutura e módulo de elasticidade dos materiais. A caracterização química dos materiais foi realizada por espectroscopia de energia dispersiva, espectrometria de emissão óptica por plasma acoplado indutivamente, análise de gases e medidas de densidade. A análise estrutural foi efetuada por difração de raios X. A análise microestrutural foi realizada por microscopia ótica, microscopia eletrônica de varredura e de transmissão. Uma análise preliminar das propriedades mecânicas da liga foi obtida por intermédio de medidas de microdureza Vickers e módulo de elasticidade dinâmico. Testes de citotoxicidade foram realizados para uma análise inicial da biocompatibilidade das ligas. Os resultados de composição química mostraram que as amostras produzidas são de muito boa qualidade, respeitando a estequiometria proposta. Os resultados estruturais e microestruturais indicam a coexistência de fases α, α’, α”, β e , dependendo da concentração de zircônio e do tratamento termomecânico realizado e, que o zircônio atua como um elemento β estabilizador no sistema de ligas proposto. Os tratamentos de solubilização são capazes de modicar as fases presentes nas amostras, pois tratamentos realizados em baixas temperaturas, induzem a precipitação da fase α”, tratamentos realizados em altas temperaturas induzem a retenção da fase β e tratamentos realizados com resfriamento lento promovem a difusão da fase α em ligas com a fase α”. Os valores de dureza e o módulo de elasticidade das ligas foram alterados com o acréscimo no teor de zircônio. A dureza aumenta, devido ao endurecimento por solução sólida e o módulo de elasticidade diminui devido à estabilização da fase β. Não foram observados efeitos citotóxicos em nenhuma das ligas preparadas.
Titanium and alloys currently are used as implants possessing excellent corrosion resistance and mechanical properties more suited to stainless steel implants and Co-Cr. The titanium alloy used for most biomedical applications is Ti-6Al-4V, however studies showed that vanadium and aluminum are harmful to human health. The objective of this study was to prepare Ti-25Ta-Zr system alloys, where the zirconium content was varied from 0 to 75 % in weight, and to analyze the influence of zirconium substitutional solute in the structure, microstructure, hardness and elastic modulus. At the same time, several annealing, lamination and solubilization treatments were carried out to modify the phases, structures, microstructure and elastic modulus of the materials. The chemical characterization of materials was performed by energy-dispersion spectroscopy, inductively coupled plasma optical emission spectrometry, gas analysis, and density measurements. The structural analysis was performed by x-ray diffraction measurements. Microstructural analysis was performed by optical, scanning and transmission electron microscopy. To verify the initial biocompatibility of the alloys, cytotoxic tests were performed. A preliminary analysis of the mechanical properties of the alloy was obtained by means of microhardness and dynamic elastic modulus measurements. The chemical composition results showed that the samples produced are of good quality, close to proposed stoichiometry. The results showed the coexistence of α, α’, α”, β e phases, depending of zirconium content and thermomechanical treatment done and, that zirconium helped the β phase stabilization. Solubilization heat treatments are capable of modifying the phases present in the samples and, treatments performed at low temperatures, induced α” phase precipitation; treatments performed at high temperatures induced β phase retention and, slow cooling treatments promoted α phase diffusion. The hardness and elastic modulus values of the alloys are changed by increasing the zirconium content. Hardness increases due to solid solution hardening and the elastic modulus decreases due to β phase stabilization. No cytotoxic effects were observed in all produced alloys.
Titanium and alloys currently are used as implants possessing excellent corrosion resistance and mechanical properties more suited to stainless steel implants and Co-Cr. The titanium alloy used for most biomedical applications is Ti-6Al-4V, however studies showed that vanadium and aluminum are harmful to human health. The objective of this study was to prepare Ti-25Ta-Zr system alloys, where the zirconium content was varied from 0 to 75 % in weight, and to analyze the influence of zirconium substitutional solute in the structure, microstructure, hardness and elastic modulus. At the same time, several annealing, lamination and solubilization treatments were carried out to modify the phases, structures, microstructure and elastic modulus of the materials. The chemical characterization of materials was performed by energy-dispersion spectroscopy, inductively coupled plasma optical emission spectrometry, gas analysis, and density measurements. The structural analysis was performed by x-ray diffraction measurements. Microstructural analysis was performed by optical, scanning and transmission electron microscopy. To verify the initial biocompatibility of the alloys, cytotoxic tests were performed. A preliminary analysis of the mechanical properties of the alloy was obtained by means of microhardness and dynamic elastic modulus measurements. The chemical composition results showed that the samples produced are of good quality, close to proposed stoichiometry. The results showed the coexistence of α, α’, α”, β e phases, depending of zirconium content and thermomechanical treatment done and, that zirconium helped the β phase stabilization. Solubilization heat treatments are capable of modifying the phases present in the samples and, treatments performed at low temperatures, induced α” phase precipitation; treatments performed at high temperatures induced β phase retention and, slow cooling treatments promoted α phase diffusion. The hardness and elastic modulus values of the alloys are changed by increasing the zirconium content. Hardness increases due to solid solution hardening and the elastic modulus decreases due to β phase stabilization. No cytotoxic effects were observed in all produced alloys.
Descrição
Palavras-chave
Ligas de Ti, Biomateriais, Microestrutura, Tratamentos térmicos, Titanium alloys, Biomaterials, Microstructure, Thermomechanical, Thermomechanical treatments