Effects of anodizing voltage on the anodized and hydrothermally treated titanium surface

Abstract

Anodic oxidation is the process of creating a titanium oxide layer with various defects more dense and stable. In this study, a dense, stable and porous oxide layer was formed using anodic spark oxidation on pure titanium surface and hydroxyapatite crystals were formed on its surface via a hydrothermal treatment. A mixture of 0.02M-GP (Glycerolphosphate disodium salt) and 0.2M-CA (Calcium acetate) was used as an electrolyte. By increasing the anodizing voltage to 220, 260, 300, and 360 V, the effects of the anodizing voltage were examined by evaluating the film properties after anodization and a hydrothermal treatment. Breakdown occurred around 230 V. As the voltage increased after breakdown, the pore size increased. After the hydrothermal treatment, the amount of HA crystal precipitation was also increased as the voltage increased. The mean surface roughness (Ra) of the anodizing surface was also increased as the voltage increased. The Ra value was larger in the hydrothermally treated group compared with the group treated with anodization as a result of the HA crystals present on the surface after the hydrothermal treatment. Corrosion resistance of the surface modified by anodization was significantly increased in a saline solution compared to that for the non-treated group; this increased further after the hydrothermal treatment. These increases were most likely due to a thick stable oxide layer formed through anodization. Thus, it is believed that titanium with its surface modified through anodic spark oxidation would be a suitable biomaterial due to its corrosion resistance and biocompatibility.

A comparison of corrosion, tribocorrosion and electrochemical impedance properties of pure Ti and Ti6Al4V alloy treated by micro-arc oxidation process

“…The high corrosion resistance of titanium and its alloys in aggressive environments, for example in chloride containing solutions, is because of the naturally formed passive TiO 2 layer having a few nm thickness. However, this thin layer is not able to resolve the necessary requirements such as biomedical one [4][5][6].…”

“…According to the published results, these coatings show a great improvement in corrosion resistance of titanium alloys, but without considerable increasing in bioactivity (low porosity) and wear resistance (low thickness) [4].…”

Surface Characterisation of Bioactive Titanium Formed Via Anodic Oxidation

“…Anodisation is a simple techniques that are useful at low temperature for TiO 2 production layers on titanium substrates and can be divided into two categories; oxidation at low voltage levels (<200V) and high voltage levels (>200V) [13]. Some studies had been done using H 2 SO 4 as an electrolyte followed by heat treatment and this studied concluded that this process is an effective method to prepare bioactive titanium [14].…”

EFEITO DAS CONDIÇÕES DE ANODIZAÇÃO EM Ti6Al4V NAS CARACTERÍSTICAS DO ÓXIDO FORMADO

“…O titânio e suas ligas exibem baixas taxas de corrosão, mesmo em ambientes agressivos (Salantiu et al, 2015), inclusive naqueles que contêm cloretos (Simka et al, 2011), devido à formação natural da camada passiva, composta por dióxido de titânio, TiO2, de espessura nanométrica (Fazel et al, 2015). Entretanto, essa fina camada, além de ser anfifílica , é levemente instável e, consequentemente, não é capaz de atender às exigências em determinadas aplicações do ramo biomédico (Diamanti e Pedeferri, 2007;Garsivaz et al, 2014;Park et al, 2006;Simka et al, 2011).…”

“…Um dos tratamentos de superfície mais recomendados e versáteis é o processo de oxidação anódica do titânio, já que é capaz de alterar as características superficiais da camada de óxido formada, as quais incluem espessura, densidade, cor, homogeneidade, morfologia, rugosidade, composição química, reatividade, cristalinidade, dentre outras (Dalmiglio et al, 2008;Diamanti e Pedeferri, 2007;Fan et al, 2012;Fazel et al, 2015;Kumar et al, 2010;Lee et al, 2010;Liu et al, 2004;Park et al, 2006;Shabani et al, 2015;Szewczenko et al, 2010;Visai et al, 2008). Essas características são fortemente influenciadas pela temperatura, pH, composição, concentração do eletrólito e por parâmetros eletroquímicos, tais como densidade de corrente e potencial aplicados (Diamanti e Pedeferri, 2007;Diamanti et al, 2011;Fan et al, 2012;Lee et al, 2010;Park et al, 2006;Simka et al, 2011;Vanhumbeeck e Proost, 2009;Walsh et al, 2009).…”