| Titanium alloy is widely used in the fields of aerospace,vehicle engineering,petro-chemical industry,biomedical and other fields because of its small density,high specific stiffness,high specific strength,low elastic modulus and good biocompatibility.It plays an important role in advanced science and technology.However,poor abrasion resistance and corrosion resistance restrict the development and application of titanium alloy greatly.In order to improve titanium alloy 's performance,it is very important to modify titanium ally via many surface technologies.As one of the important surface treatment methods,anodic oxidation can form a film on the surfaces of metal or alloy in different solutions.Therefore,this kind of method is widely used in the surface treatment engineering.It is not only simply operated with shorter time and lower cost,but also can greatly improve the performance of the surface of metal and alloy.This paper uses anodic oxidation treatment,aiming at resolving the problems of poor abrasion resistance and corrosion resistance of titanium alloy to investigate the effects of different electrolyte types,concentrations and different voltage conditions on the color,micro topography,microstructure and other performances(including film roughness,micro hardness,corrosion resistance and abrasion resistance)of anodic oxide film.The film-forming mechanism of anodic oxide film on the surface of TC4 titanium alloy was preliminarily discussed and the best anodic oxidation parameter was determined as well.The constant voltage method was adopted during anodic oxidation treatment.Three kinds of anodic electrolytes with different concentrations and different voltages were used to reach the effects of the different factors on the performances of the anodic oxide film.Phosphoric acid,sulfuric acid and the mixture of phosphoric acid and sulfuric acid(molar ratio of 1:1)consist of three kinds of electrolytes respectively.The electrolyte concentrations were 0.5mol/L,0.75mol/L,1.0mol/L and the voltages were 10V,15V,20V,25V,30V,in order to research the effect of different types and concentrations of electrolyte solutions and different voltages on the performance of the anodic oxidation films.The experimental results and theoretical analysis show that:(1)if the voltage was constant,film roughness decreased,the properties of micro hardness,abrasion resistance and corrosion resistance of the film was improved with increasing of the electrolyte concentration.(2)if the electrolyte concentration was constant,film roughness decreased,the properties of micro hardness,abrasion resistance and corrosion resistance of the film was improved with increasing of voltage.(3)Compared with the other two kinds of the acidic electrolyte,the anodic oxide film prepared in the sulfuric acid had the best performance of micro hardness and abrasion resistance,but the surface of the film was rough.In addition,corrosion resistance of the anodic oxide film is the best if the surface anodic oxidized in the mixing acidic solution.(4)Voltage is the most important factor affecting the color of the anodic oxide film.If the voltage was 10V,the anodic oxidation film was light yellow.When the voltage was 15V,the color of the anodic oxidation film turned deepened.If the voltage was 20V,the anodic oxidation film was purple.If the voltage was 25V,the anodic oxidation film was dark blue,when 30V was light blue.(5)The microstructures of the anodic oxide films were similar for TC4 titanium alloy in the three kinds of the acid electrolytes.The anodic oxide films were mainly composed by rutile TiO2,anatase TiO2,brookite TiO2 and titanium oxides TiO and Ti3O5. |
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