Wear resistance of surface-modified TiNbSn alloy

Abstract

The wear resistance of TiNbSn alloy surfaces treated by plasma nitriding, TiN sputtering, and anodic oxidation was investigated with the goal of suppressing the release of wear debris that can act as abrasive particles. Among the investigated alloys, the anodized alloy exhibited the highest hardness, adhesive strength, surface roughness, and the lowest friction coefficient (COF) under dry conditions as well as in simulated body fluids of Hank’s balanced salt solution. Wear tracks on the treated alloys, other than the anodized alloy, showed well-defined plow contours owing to adhesive galling accompanied by plastic deformation, and a significant amount of debris was observed on the wear surface. In contrast, in the anodized alloy, the wear track was barely visible (grooves were shallow), and only a few debris objects were observed. The COF under wet conditions was found to be the same as that in the dry condition for the treated alloys except for the anodized alloy, which exhibited a reduced COF under wet conditions. Significant amounts of Si originating from the counter-body SiC were observed on the worn surfaces of the treated alloys, except for the anodized alloy, and the surface of the SiC ball was severely damaged. In contrast, for the anodized alloy, no trace of Si was detected and the surface of the SiC ball was not damaged. It is concluded that the high wear resistance of the anodized alloy can be attributed to the reduced damage afforded by the strongly bonded thick oxide with a hardened rough surface, and that the hydrophilic rough surface reduced the COF under wet wear conditions.