A Study On The Preparation And Properties Of Anodic Oxide Films On The Surface Of Titanium Alloy For Biomedical Applications

Potentiostatically anodic oxidation was employed to prepare colorized anodicoxide films on Ti6Al4V(TC4) alloy. The effects of different processing parameters oncolor uniformity and properties of anodic oxide films were discussed. Surfacemorphology, elements and valence state were investigated by Scanning electronmicroscopy (SEM), X-ray photoelectron spectroscopy(XPS), and the effects onquality of anodic oxide films of pre-processing methods and sealing treatment werealso investigated.The results indicated that satisfactory colored films on TC4 alloy were obtainedby anodic oxidating in alkaline,acidic and neutral electrolyte. Electrolyte havingmoderate solubilization to dissolve oxide films, was benefit to form thicker andmore compact oxide films. Increasing of electrolyte concentration and temperatureincreased anodic oxide films forming rate. But excessive high electrolyteconcentration led to ablation defect of oxide films. Excessive high electolytetemperature resulted in loose and porous oxide films. Oxide films forming ratedecreased gradually with the increasing of anodizing time. Finally, anodic oxideformation rate was equal to the dissolution rate. According to the effect of variousfactors on corrosion resistance of oxide films, the optimlized processing parameterswere o.1mol/l H3PO4, 20?C, 5 minutes.The results of XPS showed that TiO2 was in the outer layer of the anodictitanium oxide. Furthermore, the structure of anodic films was changed fromamorphous to crystalline phase. With the increasing of oxide films depth, the contentof TiO2 gradually decreased, however, Ti2O3 and TiO were found. The thickness ofthe oxide layer after anodic oxidation was evidently thicker than nature oxide layer.In the light of colorimery and technology of computer image processing, a colorRGB recognition system was built, and realize numerization of product's color.According to numeric information obtained from this system, analyze chromatismbetween different product. By chromatism calculation, The chromatism ?ECIE ofdifferent samples obtained in the same process conditions were all lower than 1.3. Itcan not be distinguished by hunman eyes. This showed that the stability of anodicoxidation and reproducibility of color was favorable.