Study On Weatherability Of Anodized Color Films On TC4 Titanium Alloys

After a specific anodizing process,titanium and titanium alloy can obtain a colorful oxide film,which can improve corrosion resistance and decorative performance.In the field of biomedical materials,after anodizing process,titanium and titanium alloy have higher biological activity and biocompatibility on the surface,and can be used as bio-implant material.In this paper,the anodic oxidation method is used to oxidize and color the Ti6A14V（TC4）titanium alloy under different process parameters in Na OH electrolyte,H₃PO₃electrolyte and Na₂Si O₃ salt solution.The metallographic microscope,SEM,XRD,XPS,AFM and 3nh chromatic aberration test methods were used to analyze the microstructure,morphology,phase composition,thickness and color of the oxide film.In this way,the color development rule of the anodic oxidation coloring film of TC4 titanium alloy was discussed,and its color development mechanism was analyzed.The corrosion resistance of the oxidized coloring film is tested through an electrochemical workstation;the ultraviolet aging light box is used to simulate the ultraviolet environment,and the ultraviolet resistance characteristics of the color film are analyzed.Film ultraviolet absorption spectroscopy experiment to detect the absorption characteristics of titanium alloy oxide film to light color.The main conclusions are as follows:1.The color（L*,a*,b*）values of the film have a periodic variation rule with the voltage.In the anodizing stage before the arcing voltage V_b,the oxidation coloring film is composed of dense and uniform amorphous titanium oxide.The film growth mode is uniform layer growth with voltage,the macroscopic color development rule of the sample in the three electrolytes is the same;2.The color development mechanism of the oxide film is mainly the principle of thin film interference,which is the combined effect of interference-enhanced light and complementary weakened light.The theoretical calculation formula of the film thickness is derived through the correction formula of the interference optical path difference of the titanium alloy oxide film.The AFM test results are basically consistent with the theoretically calculated film thickness.The film growth rate in Na₂Si O₃salt solution is 1nm/V-1.7nm/V.3.The essential effect of oxidation process parameters and electrolyte on color is to affect the growth rate and film thickness of the film,resulting in different colors of the film.The corrosion resistance of the film layer is related to the thickness and uniformity of the film.The higher the oxidation voltage,the thicker the film layer,and the better the corrosion resistance;4.The titanium alloy oxide coloring film has better UV resistance and weather resistance.In a high-pressure steam environment,Ti O₂·H₂O is formed on the surface of the film layer,resulting in a color change.The ultraviolet absorption spectrum shows that the titanium alloy oxide colored film does not absorb visible light,and the oxide film with a voltage lower than 40V absorbs ultraviolet light.