Micro/Nanomechanical and Tribological Properties of Thin Diamond-Like Carbon Coatings

The diamond-like carbon (DLC) films with different thicknesses on 9Cr18 bearing steels were prepared using vacuum magnetic-filtering are plasma deposition. Vickers indentation, nanoindentation and nanoscratch tests were used to characterize the DLC films with a wide range of applied loads. Mechanical and tribological behaviors of these submicron films were investigated and interpreted. The hardnesses of 9Cr18 and DLC, determined by nanoindentation, are approximately 8GPa and 60GPa respectively; their elastic moduli are approximately 250GPa and 600GPa respectively. The friction coefficients of 9Cr18, DLC, organic coating, determined by nanoscratch, are approximately 0.35, 0.20 and 0.13 respectively. It is demonstrated that nanoindentation and nanoscratch tests can provide more information about the near-surface elastic-plastic deformation, friction and wear properties. The correlation of mechanical properties and scratch resistance of DLC films on 9Cr18 steels can provide an assessment for the load-carrying capacity and wear resistance.