Effects Of Normal Load On Fretting Wear Properties Of Tc21 Titanium Alloy With Plasma Electrolytic Oxidation Coatings

The effects of normal load (60, 40 and 20 N) on the tangential fretting wear properties of the TC21 titanium alloy and plasma electrolytic oxidation (PEO) coatings were investigated under displacement amplitudes of 50 and 150 mu m with a ball -on -plate contact configuration. The results show that with the increase of the displacement amplitude and decrease of the normal load, the fretting wear regime changes from partial slip regime to slip regime. In partial slip regime, the widths of the wear tracks along the fretting direction decrease with the decreasing normal load. Although there is no significant material loss, the extent of micro -cracks initiation and propagation in the micro -slip zone of the TC21 titanium alloy deepens with the decreasing normal load. However, the fretting only plays a smooth effect on the PEO coatings. In slip regime, the widths of the wear tracks along the fretting direction increase with the decreasing normal load. There exists local wear in both materials, and the wear degree increases with the increasing amplitude and decreasing normal load. The maximum wear depth of the PEO coatings is shallower than that of the TC21 titanium alloy, which proves that they could improve the fretting wear resistance.