An investigation of the effect of surface roughness and coating thickness on the friction and wear behaviour of a commercial MoS2–metal coating on AISI 400C steel

The objective of the present experimental work was to investigate the influence of substrate surface roughness and coating thickness on the friction and wear behaviour of AISI 440C steel-coated with MoST under pure sliding with oil lubrication. An AISI 52100 bearing steel ball was slid at 0.5 m/s against the coated steel disc using an applied normal load of 50 N. This gave a mean Hertzian pressure of 0.75 GPa. Friction and wear maps were constructed from the experimental data. Wear resistance was greatest when a coating thickness of 1 μm was used and when the substrate surface roughness (Ra) was 0.1 μm or below.