Friction and wear of a-C:H films deposited at different bias in air and NaCl solution

a-C:H films were produced on 316 L stainless steel via magnetron sputtering technique. The effects of bias voltage on the composition, structure and properties of the films were studied. The sp 2 C fraction grows as the bias voltage increases, and the internal stress and hardness increase constantly. In ambient air, the films deposited at -150 V have the lowest friction coefficient (COF) of 0.095, while those at -30 V have the lowest COF of 0.028 in salt solution, benefiting from the higher H content. The corrosion resistance of the film is affected comprehensively by the thickness, surface morphology, sp 2 clusters and transition layer. The a-C:H film at -60 V has the lowest corrosion current density (5.41×10 -11 A/cm 2 ) and the highest protection efficiency (99.8%). • The microstructure and composition of the a-C:H films were tailored by the bias. • The lowest friction coefficient in ambient air was 0.095 at the bias of -150V. • The lowest average friction coefficient in saline environment was 0.028 at -30 V. • The anti-corrosion protection efficiency of the 316 L substrate achieved 99.8% at -60V.