Effects of intrinsic mechanical properties on the dynamic bonding strength of GLC films undergoing ball bearing contact fatigues.

Wear-resistant films, which are widely applied to extend the service life of the gears and bearings, usually surfer from dynamic bonding fatigue failure induced by the Hertz-like contact. However, there is still lack of research on the influence of the main mechanical parameters of films on the dynamic bonding fatigue failure mechanism. In this work, graphite-like carbon (GLC) films with a low friction coefficient and different Ti doping ratios were deposited on the surface of stainless steel via direct current magnetron sputtering (DCMS) technology. The microstructure and mechanical properties of the films before and after vacuum annealing were investigated by SEM, Raman, and nanoindentation, and the dynamic bonding failure life of the films were evaluated by the ball-bearing-disc method with dynamic contact fatigue loads. The results revealed that the critical dynamic bonding strength exhibited a significant function dependence on the values of hardness-to-elastic modulus (H3/E2) parameters of the GLC films. The film failure mechanism showed a transition from the film/substrate interface spalling mode to the near-surface cohesion shear spalling mode with the increase of H3/E2. [Display omitted] • GLC films with low friction coefficient and different Ti doping ratios were deposited on stainless steel. • Vacuum annealing treatment leads to changes in the mechanical properties and carbon phase. • The increase of H3/E2 ratio can significantly enhance fatigue life and change the failure behaviours of the GLC films. • The reasons for the difference in failure mechanisms of films at dynamic bonding fatigue strength test were analysed. [ABSTRACT FROM AUTHOR]