Synergistic effect of surface texturing and coating on the friction between piston ring and cylinder liner contact

It is well-established that the piston ring/cylinder liner (PRCL) contact is the major contributor to friction losses in the internal combustion engine. While numerous studies have evaluated the individual effect of surface engineering techniques like surface texturing, coating, on the PRCL system, however, its combined effect has not been thoroughly explored. In this work, the combined effect of surface coating and texturing on the frictional properties of piston ring/cylinder liner (PRCL) contact in different lubrication regimes has been simulated using a reciprocating tribometer rig. A cylinder liner of cast iron material and three different types of piston ring coatings, namely Diamond-like-carbon (DLC), chrome, and moly-chrome-ceramic (MCC) were used as samples. Under all lubrication regimes, the coated samples with texturing had better frictional performance compared to non-textured coated samples. The maximum friction reduction was observed for textured DLC coated samples under boundary lubrication regime. This behaviour was proposed to be a result of the synergistic effect of graphitisation and texturing.