Electrochemical formation of oxide films on Ti6Al4V alloy

Abstract

The results of the study of the process of electrochemical oxidation of Ti6Al4V titanium alloy in solutions of tartaric, citric and oxalic acids are presented. It is shown that the nature of the forming dependencies of the alloy depends on the magnitude of the current density. When ja<0,5 A∙dm–2, a continuous oxide film does not form on the alloy surface and the specified voltage value is not reached. At ja>0,5 A∙dm–2, a continuous oxide film forms on the surface of the alloy and linear dependences are observed. Films produced under these conditions are interference colored. The maximum thickness of the film is determined by the specified value of the forming voltage U and does not depend on other parameters of electrolysis. For a number of identical values of U, the dependence of the limiting film thickness has a linear form. The color of the oxide film is determined by the voltage value and does not depend on the current density and electrolyte concentration. It is established that the color of the film corresponds to the magnitude of the forming voltage in the range of 10–100 V. The effect is due to the fact that film formation during anodic polarization occurs under the presence of a potential gradient, the magnitude of which is constant for titanium. An increase in a given value of U leads to a proportional increase in the limiting thickness of the oxide, which determines the color of its color. The research results to determine the effect of electrolysis parameters on the characteristics of oxide films make it possible to substantiate the regime for producing TiO2 films on the surface of the Ti6Al4V alloy. The obtained data are the basis for the development of technology for the electrochemical oxidation of titanium alloys to give their surface functional properties