Análise comparativa da resistência à corrosão eletroquímica da liga de Ti-6Al-4V e do aço inoxidável AISI316L obtidas por manufatura aditiva visando aplicações biomédicas
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Data
2017-09-01
Autores
Jaime, Gustavo Carneiro [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A procura por materiais, com compatibilidade e funcionalidade biológicas, que possam melhorar a qualidade da vida humana é constante, além da busca de processos de fabricação que atendam às necessidades de manufatura de artefatos de geometria complexa. Os artefatos de aço inoxidável são utilizados por possuírem uma boa biocompatibilidade, baixo custo de produção, mas podem liberar íons como o cobalto, que é carcinogênico. O uso de Ligas de titânio é uma boa alternativa, já que possuem uma maior resistência à corrosão e boa resposta biológica, porém, seu custo é muito elevado. Considerando esses aspectos, o presente trabalho foi realizado buscando estudar, comparativamente, as características de microdureza, microdesgaste e resistência à corrosão de artefatos manufaturados para aplicações biomédicas, aproveitando as características mecânicas da liga de aço inoxidável AISI316L, usado como substrato, com as características eletroquímicas apresentadas pela liga de titânio Ti-6Al-4V, usado como material de tratamento de superfície. A sinterização direta dos metais por laser (DMLS) foi o processo de manufatura escolhido por apresentar as características de fabricação desejadas. Os ensaios realizados foram o de microdureza Vickers, ensaio de desgaste microadesivo por esfera rotativa fixa (esfera-fixa) e para o comparativo da resistência à corrosão eletroquímica foram produzidas curvas de polarização potenciodinâmicas que forneceram os seguintes parâmetros: o potencial de corrosão, a densidade de corrente e a resistência a polarização. A análise qualitativa das amostras foi feita com o uso de microscopia óptica e microscopia eletrônica de varredura. Os ensaios de microdureza e desgaste microadesivo mostraram um aumento significativo na dureza das amostras com a adição de camadas de Ti-6Al-4V, com consequente diminuição do desgaste, enquanto o ensaio de resistência à corrosão eletroquímica demonstrou a resistência contra corrosão eletroquímica dessas ligas. Nas microscopias foram observados material não sinterizado e diluição de substrato nas ligas de Ti-6Al-4V durante o processo DMLS.
The search for materials with biological compatibility and functionality that can improve the quality of human life is constant, as well as the search for manufacturing processes that meet the needs of the manufacture of complex geometry artifacts. Stainless steel artifacts are widely used because they have good biocompatibility, low production cost, but can release ions such as cobalt, which is carcinogenic. The use of titanium alloys is a good alternative, since titanium has a higher resistance to corrosion and good biological response, however, its final cost is very high. Considering these aspects, the present work was carried out in order to study the characteristics of microhardness, micro-wear and corrosion resistance of manufactured artifacts for biomedical applications, taking advantage of the mechanical characteristics of the AISI316L stainless steel alloy, used as a substrate, with the electrochemical characteristics presented by titanium alloy Ti-6Al-4V, used as surface treatment material. The direct sintering of metals by laser (DMLS) was the manufacturing process chosen because it presented the desired manufacturing characteristics. The tests were carried out using Vickers microhardness test, fixed-sphere microadhesive test (fixed-sphere) and for the comparison of resistance to electrochemical corrosion, potentiodynamic polarization curves were produced which provided the following parameters: corrosion potential, current density and polarization resistance. The qualitative analysis of the samples was done with the use of optical microscopy and scanning electron microscopy. The microhardness and microadhesive wear tests showed a significant increase in the hardness of the samples with the addition of Ti-6Al-4V layers, with consequent reduction of wear, while the electrochemical corrosion resistance test demonstrated the resistance against electrochemical corrosion of these alloys. Non-sintered material and substrate dilution were observed in the Ti-6Al-4V alloy during the DMLS process.
The search for materials with biological compatibility and functionality that can improve the quality of human life is constant, as well as the search for manufacturing processes that meet the needs of the manufacture of complex geometry artifacts. Stainless steel artifacts are widely used because they have good biocompatibility, low production cost, but can release ions such as cobalt, which is carcinogenic. The use of titanium alloys is a good alternative, since titanium has a higher resistance to corrosion and good biological response, however, its final cost is very high. Considering these aspects, the present work was carried out in order to study the characteristics of microhardness, micro-wear and corrosion resistance of manufactured artifacts for biomedical applications, taking advantage of the mechanical characteristics of the AISI316L stainless steel alloy, used as a substrate, with the electrochemical characteristics presented by titanium alloy Ti-6Al-4V, used as surface treatment material. The direct sintering of metals by laser (DMLS) was the manufacturing process chosen because it presented the desired manufacturing characteristics. The tests were carried out using Vickers microhardness test, fixed-sphere microadhesive test (fixed-sphere) and for the comparison of resistance to electrochemical corrosion, potentiodynamic polarization curves were produced which provided the following parameters: corrosion potential, current density and polarization resistance. The qualitative analysis of the samples was done with the use of optical microscopy and scanning electron microscopy. The microhardness and microadhesive wear tests showed a significant increase in the hardness of the samples with the addition of Ti-6Al-4V layers, with consequent reduction of wear, while the electrochemical corrosion resistance test demonstrated the resistance against electrochemical corrosion of these alloys. Non-sintered material and substrate dilution were observed in the Ti-6Al-4V alloy during the DMLS process.
Descrição
Palavras-chave
Wear., Hardness., Corrosão eletroquímica, DMLS, Aço inoxidável, Ti-6Al-4V, Desgaste, Dureza, Electrochemical corrosion, DMLS, Stainless steel