Caracterização química, biológica e mecânica da liga Zr-25Ta-5Ti visando aplicações biológicas
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Data
2022-03-14
Autores
Saraiva, Edriely de Oliveira
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A expectativa de vida aumentou 31,1 anos desde 1940, e com esse crescente
envelhecimento da população aumentou também a demanda por materiais biomédicos
que possam reparar ou substituir funções do corpo humano. O titânio é amplamente
utilizado em aplicações biomédicas devido às suas propriedades físicas, químicas e
biológicas. O zircônio possui propriedades químicas e físicas semelhantes ao titânio,
possuindo também duas estruturas cristalinas. É mais estável com estrutura hexagonal
compacta, conhecida como α. Em temperaturas mais altas, sua estrutura cristalina é
cúbica de corpo centrado, a fase β. Com a adição de outros elementos, é possível
alterar a temperatura de transformação alotrópica para modificar as frações
volumétricas da fase conforme desejado. O tântalo adicionado ao zircônio é excelente
para biocompatibilidade e estabilização da fase β. O titânio auxilia na
biocompatibilidade e é um estabilizador β. Estudos na literatura mostram que ligas com
predominância da fase β apresentam maior compatibilidade mecânica com o osso
humano. Assim, neste trabalho, ligas de zircônio contendo 25%p de tântalo e 5%p de
titânio foram preparadas e caracterizadas O lingote foi preparado em um forno de fusão
a arco e foi submetido a um tratamento térmico a 1000°C por 24 horas em vácuo de
10-
7
torr para homogeneizar a liga e aliviar as tensões residuais de fusão. O lingote foi
então laminado a quente e foi refrigerado a ar, com acabamento de aproximadamente
4 mm de espessura. Para análise química foram efetuadas medidas de densidade e
composição química. As caracterizações estruturais e microestruturais da liga foram
realizadas por meio de difração de raios X e imagens de micrografias ópticas (OM) e
eletrônicas de varredura (SEM). Para a caracterização mecânica foram realizadas
medições de microdureza e módulo de elasticidade nas três condições de liga, e por
último, foram realizados testes de MTT e cristal violeta para avaliar a citotoxicidade e
adesão celular das ligas. Os resultados mostraram que a liga teve uma fusão
adequada, devido ao valor de densidade e a análise de composição química. As
análises estrutural e microestrutural mostraram a presença das fases α, β e ω. A dureza
da liga é superior ao titânio e ao zircônio, porém após o processo de laminação o valor
tornou-se mais viável para aplicações biomédicas. O módulo de elasticidade mostra
que a adição de tântalo diminuiu o módulo, devido à fase β que possui menor
densidade, comparando com o Ti-cp e outras ligas comerciais como as ligas de cobalto
e cromo; e testes biológicos indicaram que as ligas não são citotóxicas, demonstrando
propriedades de ligas com potencial para futuras aplicações biomédicas
Life expectancy has increased by 31.1 years since 1940, and with this growing aging population has also increased the demand for biomedical materials that can repair or replace functions of the human body. Titanium is widely used in biomedical applications due to its physical, chemical, and biological properties. Zirconium has chemical and physical properties like titanium, also having two crystalline structures. It is more stable with compact hexagonal structure, known as α. At higher temperatures, its crystalline structure is body-centered cubic, the phase β. With the addition of other elements, it can possible to change the allotropic transformation temperature to modify the volumetric fractions of the phase as desired. Tantalum added to zirconium is excellent for biocompatibility and stabilization of the β. Titanium assists in biocompatibility and is a β- stabilizer element. Studies in the literature show that alloys with predominance of the β phase present higher mechanical compatibility with human bone. Thus, in this work, zirconium alloys containing 25 wt% tantalum and 5 wt% titanium were prepared and characterized. The ingot was prepared in an arc-melting furnace and was subjected to heat treatment at 1.000 °C for 24 hours in a vacuum of 10-7 Torr to homogenize the alloy and relieve residual melting stresses. The ingot was then hot rolled and air-cooled, with a finish approximately 4 mm thickness. For chemical analysis, density and chemical composition measurements were performed. The structural and microstructural characterizations of the alloy were performed by X-ray diffraction and optical micrograph (OM) and scanning electronics (SEM) images. For the mechanical characterization, microhardness and modulus of elasticity measurements were performed in the three alloy conditions, and finally, MTT and violet crystal tests were performed to evaluate the cytotoxicity and cell adhesion of the alloys. The results showed that the alloy had an adequate melting, due to the density value and chemical composition analysis. Structural and microstructural analyses showed the presence of the α, β and ω phases. The hardness of the alloy is superior to titanium and zirconium, but after the hot-rolling process the value has become more viable for biomedical applications. The modulus of elasticity shows that the addition of tantalum decreased the modulus, due to the β phase that has lower density, compared with Ti-cp and other commercial alloys such as cobalt and chromium alloys; and biological tests indicated that the alloys are not cytotoxic, demonstrating alloy properties with potential for future biomedical applications
Life expectancy has increased by 31.1 years since 1940, and with this growing aging population has also increased the demand for biomedical materials that can repair or replace functions of the human body. Titanium is widely used in biomedical applications due to its physical, chemical, and biological properties. Zirconium has chemical and physical properties like titanium, also having two crystalline structures. It is more stable with compact hexagonal structure, known as α. At higher temperatures, its crystalline structure is body-centered cubic, the phase β. With the addition of other elements, it can possible to change the allotropic transformation temperature to modify the volumetric fractions of the phase as desired. Tantalum added to zirconium is excellent for biocompatibility and stabilization of the β. Titanium assists in biocompatibility and is a β- stabilizer element. Studies in the literature show that alloys with predominance of the β phase present higher mechanical compatibility with human bone. Thus, in this work, zirconium alloys containing 25 wt% tantalum and 5 wt% titanium were prepared and characterized. The ingot was prepared in an arc-melting furnace and was subjected to heat treatment at 1.000 °C for 24 hours in a vacuum of 10-7 Torr to homogenize the alloy and relieve residual melting stresses. The ingot was then hot rolled and air-cooled, with a finish approximately 4 mm thickness. For chemical analysis, density and chemical composition measurements were performed. The structural and microstructural characterizations of the alloy were performed by X-ray diffraction and optical micrograph (OM) and scanning electronics (SEM) images. For the mechanical characterization, microhardness and modulus of elasticity measurements were performed in the three alloy conditions, and finally, MTT and violet crystal tests were performed to evaluate the cytotoxicity and cell adhesion of the alloys. The results showed that the alloy had an adequate melting, due to the density value and chemical composition analysis. Structural and microstructural analyses showed the presence of the α, β and ω phases. The hardness of the alloy is superior to titanium and zirconium, but after the hot-rolling process the value has become more viable for biomedical applications. The modulus of elasticity shows that the addition of tantalum decreased the modulus, due to the β phase that has lower density, compared with Ti-cp and other commercial alloys such as cobalt and chromium alloys; and biological tests indicated that the alloys are not cytotoxic, demonstrating alloy properties with potential for future biomedical applications
Descrição
Palavras-chave
Ligas de zircônio, Biomateriais, Caracterização, Zircônio, Zirconium alloys, Biomaterials, Zirconium