Influence of Deposition Positions on Fretting Behaviors of DLC Coating on Ti-6Al-4V

The influence of diamond-like carbon (DLC) coating positions-coated flat, coated cylinder, and self-mated coated surface tribopairs-on the fretting behaviors of Ti-6Al-4V were investigated using a fretting wear test rig with a cylinder-on-flat contact. The results indicated that, for tests without coating (Ti-6Al-4V-Ti-6Al-4V contact), the friction (Q(max)/P) was high (0.8-1.2), wear volumes were large (0.08-0.1 mm(3)) under a large displacement amplitude of +/- 40 mu m and small (close to 0) under a small displacement amplitude of +/- 20 mu m, and the wear debris was composed of Ti-6Al-4V flakes and oxidized particles. For tests with the DLC coating, under low load conditions, the DLC coating was not removed or was only partially removed, Q(max)/P was low (<= 0.2), and the wear volumes were small. Under high load conditions, the coating was entirely removed, Q(max)/P was high (0.6-0.8), and the wear volumes were similar to those in tests without coating. The wear debris was composed of DLC particles, Ti-6Al-4V flakes, and oxidized particles. The DLC coating was damaged more severely when deposited on a flat surface than when deposited on a cylindrical surface. The DLC coating was damaged more severely when sliding against a DLC-coated countersurface than when sliding against the Ti-6Al-4V alloy.