Tribological Properties of TC4 Ti-Alloy Surfaces Modified by Anodizing Coloring

TC4 Ti-alloy surfaces were modified by anodizing coloring.The influence of the anodic voltage on the color and tribological behavior was investigated.The results show that the anodic voltage had a major impact.To be specific,as the anodic voltage increased from 10 to 80 V,the thickness of compact,uniform,smooth Ti-oxide layer increased,the hardness and wear-resistance changed in an increase-decrease mode,maximizing at 50 V;and the color varied in a spectrum of dark-brown,purple,lake-blue,pink,dark-blue,yellow,light-green and light-yellow.Moreover,we found that the wet-etching and chemical polishing of the substrate significantly improved the flatness,thickness uniformity,evenness and beauty of color,and that post-sealing of the Ti-oxide in de-ionized water at 90℃ cosiderablly increased the stability and contamination-resistance in air,because OH^-1 radicals turned Ti-oxide into hydrous Ti-oxide,effectively sealing micrro-pores in the more porous top oxide-layer.