Novas ligas do sistema Ti-5Mo-Nb para aplicações biomédicas
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Data
2022-04-28
Autores
Cardoso, Giovana Collombaro
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Universidade Estadual Paulista (Unesp)
Resumo
O titânio e suas ligas são amplamente utilizados em implantes cardiovasculares, odontológicos e ortopédicos devido ao excelente conjunto de propriedades que esses materiais possuem, como módulo de elasticidade mais baixo, alta resistência à corrosão e biocompatibilidade, comparados com outros biomateriais metálicos. A liga de titânio mais utilizada atualmente é a Ti-6Al-4V, porém problemas em relação à citotoxidade do vanádio e a associação da liberação de íons de alumínio no corpo com o desenvolvimento de desordens neurológicas, vem incentivando o desenvolvimento de novas ligas com outros elementos que melhorem ainda mais as boas propriedades do titânio e que não sejam prejudiciais ao organismo, como o molibdênio e o nióbio. Assim, nesse trabalho, novas ligas do sistema Ti-5Mo-xNb (x = 0, 10, 20 e 30 %p) foram desenvolvidas e caracterizadas química, estrutural, microestrutural e mecanicamente. Os lingotes foram fundidos em um forno a arco-voltaico, com atmosfera inerte de argônio. Após a fusão, as amostras foram tratadas termicamente para garantir a homogeneização dos elementos de liga, laminadas a quente e recozidas. A análise química envolveu medidas de densidade, composição química semiquantitativa por Espectroscopia por Dispersão de Energia de Raios X (EDS) e mapeamento químico. A estrutura e microestrutura das amostras foram analisadas por difração de raios X, com refinamento pelo método de Rietveld, e com imagens de microscopia óptica e eletrônica de varredura. Ensaios de módulo de elasticidade dinâmico e microdureza foram efetuados para a caracterização mecânica e testes de viabilidade e adesão celular avaliaram a citotoxidade in vitro das ligas produzidas. Os resultados mostraram que a adição de nióbio promoveu aumento da fase β do titânio. A quantidade dos elementos substitucionais e os diferentes tratamentos termomecânicos influenciaram na microestrutura e propriedades mecânicas das ligas. A liga Ti-5Mo-30Nb mostrou melhor potencial para futuras aplicações biomédicas.
Titanium and its alloys are widely used in cardiovascular, dental, and orthopedic implants due to their excellent properties, such as lower elastic modulus, high corrosion resistance, and biocompatibility, compared to other metallic biomaterials. The most used titanium alloy today is Ti-6Al-4V. However, problems related to the cytotoxicity of vanadium and the association of the release of aluminum ions in the body with the development of neurological disorders have encouraged the development of new alloys with other elements that further improve the good properties of titanium and that are not harmful to the body, such as molybdenum and niobium. Thus, in this work, new alloys of the Ti-5Mo-xNb system (x = 0, 10, 20, and 30 wt%) were developed and characterized chemically, structurally, microstructurally, and mechanically. The ingots were arc melted in argon gas atmosphere. After melting, the samples were heat-treated to ensure homogenization of the alloying elements, hot rolled, and annealed. The chemical analysis involved density measurements, semi-quantitative chemical composition by energy-dispersive X-ray spectrometry (EDS), and chemical mapping. The structure and microstructure of the samples were analyzed by X-ray diffraction, with refinement by the Rietveld method, and with optical and scanning electron microscopy images. Young's modulus and microhardness tests were performed for mechanical characterization, and cell viability and adhesion tests evaluated the in vitro cytotoxicity of the produced alloys. The results showed that the addition of niobium promoted an increase in the β phase of titanium. The amount of substitutional elements and the different thermomechanical treatments influenced the microstructure and mechanical properties of the alloys. Ti-5Mo-30Nb alloy showed better potential for future biomedical applications.
Titanium and its alloys are widely used in cardiovascular, dental, and orthopedic implants due to their excellent properties, such as lower elastic modulus, high corrosion resistance, and biocompatibility, compared to other metallic biomaterials. The most used titanium alloy today is Ti-6Al-4V. However, problems related to the cytotoxicity of vanadium and the association of the release of aluminum ions in the body with the development of neurological disorders have encouraged the development of new alloys with other elements that further improve the good properties of titanium and that are not harmful to the body, such as molybdenum and niobium. Thus, in this work, new alloys of the Ti-5Mo-xNb system (x = 0, 10, 20, and 30 wt%) were developed and characterized chemically, structurally, microstructurally, and mechanically. The ingots were arc melted in argon gas atmosphere. After melting, the samples were heat-treated to ensure homogenization of the alloying elements, hot rolled, and annealed. The chemical analysis involved density measurements, semi-quantitative chemical composition by energy-dispersive X-ray spectrometry (EDS), and chemical mapping. The structure and microstructure of the samples were analyzed by X-ray diffraction, with refinement by the Rietveld method, and with optical and scanning electron microscopy images. Young's modulus and microhardness tests were performed for mechanical characterization, and cell viability and adhesion tests evaluated the in vitro cytotoxicity of the produced alloys. The results showed that the addition of niobium promoted an increase in the β phase of titanium. The amount of substitutional elements and the different thermomechanical treatments influenced the microstructure and mechanical properties of the alloys. Ti-5Mo-30Nb alloy showed better potential for future biomedical applications.
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Palavras-chave
Ligas de titânio, Titanium alloys, Biomaterial, Molibdênio, Molybdenum, Niobium, Nióbio, Módulo de elasticidade, Young’s modulus