Investigation of the evolution and corrosion resistance mechanism of anodized film on Ta surface

The tantalum oxide film was fabricated using an anodization process in a 0.5M H2SO4 electrolyte. The evolution and corrosion resistance mechanism of anodized film on the Ta surface has been investigated by experiments and theoretical calculations. The results indicate that the sample with an anodic oxidation voltage of 20V and an anodic oxidation time of 60 min (Ta20-60) exhibits the thickest oxidation film, measuring 360.00 nm and comprising an outer porous layer and an inner dense layer. Ta20-60 demonstrates the highest Ecorr value of 0.009 V and the lowest Icorr value of 0.879 mu A cm(-2), with a minimal density of point defects at 1.24 x 10(19) cm(-3), which imparts superior corrosion resistance. The calculation result shows that the growth rate of Ta anodic oxidation film is controlled by the diffusion and migration of vacancy defects. The O atom passes through one bridge site from the tetrahedral gap to another tetrahedral gap (Path 1) on the complete (110) surface has a low diffusion barrier of 0.470 eV and the shortest diffusion path of 2.04 angstrom, which is the most favorable path for the diffusion of O atoms. This paper offers a fresh perspective on the corrosion resistance of tantalum while furnishing guidance for improving Ta oxide film performance.