Study of the fatigue wear behaviors of a tungsten carbide diamond-like carbon coating on 316L stainless steel

摘要

A tungsten carbide (WC) diamond-like carbon (DLC) hard coating has higher lubricity and resilience than other types of nitride-, carbide- and oxide-based ceramic coatings. To evaluate the anti-wear properties of the DLC coating under extremely high impact-sliding loading conditions, a newly developed method, called the cycled inclined impact-sliding test, is introduced and utilized to study fatigue wear behaviors of the DLC coating under a combination of an impact force, Fi, and pressing force, Fp (Fi/Fp = 200 N/400 N), for up to 10 000 cycles. A 10 mm steel (AISI 52100) bearing ball is used as the impacting and sliding object. Due to the low coefficient of friction of the WC DLC coating against the steel counterface, which creates a reduced tangential force on the coating surface and less tensile stress within the coating, the WC DLC coating exhibits high endurance when impacted in dry air conditions. A scanning electron microscopy study showed that different types of fatigue wear cracks appeared and were distributed in the different areas (head and tail parts) of the impact and sliding tracks. Most of those cracks penetrated the coating and caused sawtooth-like deformation in the substrate. Material transfer from the counterface ball was not detected by energy-dispersive x-ray spectroscopy.