Fretting wear studies on diamond-like carbon coated Ti–6Al–4V

This work is concerned with the performance of diamond-like carbon (DLC) coated Ti–6Al–4V flat samples fretted against alumina ball in two environments—ambient air and simulated body fluid (Ringer solution). Hydrogenated DLC (H-DLC) coatings were prepared by radio frequency plasma enhanced chemical vapour deposition process. Raman scattering measurements were done on the coatings. Fretting wear tests were conducted at different normal loads using a fretting wear test rig working on scotch yoke mechanism. Wear scars on the tested specimens were observed using an optical microscope. Wear volume was calculated based on wear scar diameter measured along parallel and perpendicular to the fretting direction. Tangential force coefficient (TFC) values exhibited by DLC coated samples were lower than those exhibited by uncoated specimens in both ambient air and Ringer solution. Very low TFC values and low wear volume were observed for H-DLC coated samples tested in air at lower loads of 1.9 N and 4.9 N. It was attributed to occurrence of graphitisation and formation of transfer layer on alumina ball.