Influence of diamond-like carbon coatings and roughness on fretting behaviors of Ti-6Al-4V for neck adapter-femoral stem contact

Influences of diamond-like carbon (DLC) coatings and roughness on fretting behaviors of Ti-6Al-4V were investigated using a fretting-wear test rig with a cylindrical-on-flat surface contact. The results indicated that, without the DLC coating, the friction coefficient was high; the wear volume was high under large-displacement conditions. Smoother surfaces extended the gross slip regime to smaller-displacement and higher-normal-force conditions. For tests on DLC coating, the coating response wear maps could be divided into three areas: the coating working area (small-displacement and low-normal-force conditions), the coating failure area (large-displacement and high-normal-force conditions), and the transition area. In the coating working area, DLC coatings could protect the substrate with low friction, low wear volume, and mild damage in the coatings; the running condition lied within the gross slip regime. The harder and stiffer DLC A coating presented better fretting resistance than that of DLC B coating. Coatings on smooth surfaces exhibited better tribological performance than on rough surfaces. The increase in the normal force and displacement accelerated the coating failure process.