Surface modification of CP-Ti to improve the fretting-corrosion resistance: Thermal oxidation vs. anodizing

Fretting corrosion is one of the important reasons for the failure of prosthesis made of titanium and titanium alloys under in vivo condition. The fretting-corrosion behaviour of untreated, anodized and thermally oxidized commercially pure titanium (CP-Ti) in Ringer's solution was evaluated based on the change in free corrosion potential (FCP) measured as a function of time. A comparison of the performance of untreated, anodized and thermally oxidized CP-Ti under fretting-corrosion conditions is reported for the first time in this paper. The study reveals that surface modification of CP-Ti by both anodizing and thermal oxidation improved the fretting-corrosion resistance of CP-Ti and among them the performance of thermally oxidized CP-Ti is superior to that of the anodized one. Adhesive galling is the predominant wear mechanism for untreated CP-Ti, adhesive wear and delamination are found to be operative for anodized CP-Ti whereas an abrasive wear mechanism is operative for thermally oxidized CP-Ti when they are fretted against an alumina ball.