Variações morfológicas e estruturais nos filmes de TiO2 formados pela anodização de titânio
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Data
2019-02-27
Autores
Palma, Dener Pedro da Silva
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Nas últimas décadas houve um enorme crescimento do uso titânio comercialmente puro nos mais variados setores da economia como por exemplo na indústria petrolífera, aeroespacial e biomédica. Na indústria biomédica o uso desse metal se caracteriza por ter propriedades mecânicas semelhantes às do osso do corpo humano, por apresentar excelente resistência à corrosão quando comparado com outros metais, e também por ser biocompatível. A biocompatibilidade do titânio ocorre em função da camada de óxido que é formada sobre a superfície deste metal quando exposto a uma atmosfera em que há a presença de oxigênio. Esta camada pode ser amorfa ou cristalina, geralmente quando formada espontaneamente os filmes são amorfos, porém para o uso biomédico é interessante que a fase cristalina anatase se forme sobre a superfície do titânio, pois de acordo com a literatura esta fase favorece a osseointegração. Sendo assim várias técnicas de modificação de superfície, como por exemplo, anodização, tratamento térmico, eletrodeposição, são estudadas para melhorar as propriedades da camada de TiO2. Por tanto, o objetivo desse trabalho foi investigar como os parâmetros de anodização e características de filmes anódicos estão relacionados. Os filmes foram obtidos por anodização em soluções de 0,25 e 2,5 mol L-1 de H3PO4 em três tempos de anodização (3, 6 e 12 horas), comparando dois tipos de substratos: superfícies de titânio eletropolidas e polidas com alumina, com a finalidade de obter uma superfície mais biocompatível por meio da formação de anatase. A fim de verificar os efeitos do tratamento térmico na camada de óxido, as amostras anodizadas em 3 horas foram submetidas à temperatura de 450 °C por uma hora em atmosfera inerte. Para a caracterização da camada de óxido formada utilizou-se micrografias via MEV, espectros Raman e DRX. Estas técnicas mostraram o efeito do polimento superficial sobre o crescimento do filme, ou seja, verificou-se que o filme se formou mais rapidamente na superfície polida com alumina, em comparação aos substratos de titânio eletropolidos.
In the last decades, there has been a great growth in the use of commercially pure titanium in the most varied sectors of the economy, such as in the aerospace and biomedical industries. In the biomedical industry the use of this metal is due to its properties, such as mechanical strength, which is similar to human bone, as well as its excellent corrosion resistance compared to other metals, and also because of it is a biocompatible element. The biocompatibility of titanium occurs as a function of the oxide layer formed on the surface of this metal when it is exposed to an atmosphere where there is the presence of oxygen. This layer can be amorphous or crystalline, usually when it is formed spontaneously the films are amorphous, but for biomedical use it is interesting that the morphology of the anodic film is composed by the Crystalline phase of the anatase, because according to the literature this phase favors osseointegration. In order to improve the properties of the titanium oxide layer, various surface modification techniques have been studied, such as anodizing, heat treatment and electrodeposition. Thus, the proposal of this work was to investigate how the anodization parameters and the characteristics of anodic films are related. The films were obtained by anodization in 0.25 and 2.5 mol L-1 H3PO4 solutions in three anodization times (3, 6 and 12 hours), comparing two types of substrates: electropolished and non-electropolished titanium surfaces, aimed to create a more biocompatible surface through anatase formation. In order to verify the effects of the heat treatment on the oxide layer, the samples anodized after 3 hours were subjected to a temperature of 450 °C for one hour in an inert atmosphere. The characterization of the anodic oxide layer was performed using SEM, Raman and XRD analysis. The obtained results showed the effect of the surface polishing on the growth of the films, that is, the films were found to have formed more rapidly on the polished surface using alumina compared to the electropolished substrates.
In the last decades, there has been a great growth in the use of commercially pure titanium in the most varied sectors of the economy, such as in the aerospace and biomedical industries. In the biomedical industry the use of this metal is due to its properties, such as mechanical strength, which is similar to human bone, as well as its excellent corrosion resistance compared to other metals, and also because of it is a biocompatible element. The biocompatibility of titanium occurs as a function of the oxide layer formed on the surface of this metal when it is exposed to an atmosphere where there is the presence of oxygen. This layer can be amorphous or crystalline, usually when it is formed spontaneously the films are amorphous, but for biomedical use it is interesting that the morphology of the anodic film is composed by the Crystalline phase of the anatase, because according to the literature this phase favors osseointegration. In order to improve the properties of the titanium oxide layer, various surface modification techniques have been studied, such as anodizing, heat treatment and electrodeposition. Thus, the proposal of this work was to investigate how the anodization parameters and the characteristics of anodic films are related. The films were obtained by anodization in 0.25 and 2.5 mol L-1 H3PO4 solutions in three anodization times (3, 6 and 12 hours), comparing two types of substrates: electropolished and non-electropolished titanium surfaces, aimed to create a more biocompatible surface through anatase formation. In order to verify the effects of the heat treatment on the oxide layer, the samples anodized after 3 hours were subjected to a temperature of 450 °C for one hour in an inert atmosphere. The characterization of the anodic oxide layer was performed using SEM, Raman and XRD analysis. The obtained results showed the effect of the surface polishing on the growth of the films, that is, the films were found to have formed more rapidly on the polished surface using alumina compared to the electropolished substrates.
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Palavras-chave
Titânio, Anodização, Eletropolimento, Biomateriais, técnicas de modificação de superfície, Titanium, Anodizing, Electropolish, Biomaterials, Anatase, Surface modification techniques, Anatase, Metais - Oxidação anódica, Polimento Eletrolítico, Materiais biomédicos