Experimental Investigation on the Effect of Using PVD and DLC Coatings on The Wear Properties of The Internal Combustion Engine Piston Ring

The composition of the coating used In the piston ring has a great effect on friction and wear in combustion engines. In the present study, the wear behavior of three samples of TU3 engine ring with hard chromium, chromium nitride, and diamond-like carbon coatings were studied and compared. Various coating properties including chemical composition, microstructure, thickness, roughness, and hardness were studied. Also, the microstructure and wear mechanism was studied using a scanning electron microscope (SEM) and energy dispersive analysis (EDX). A reciprocating wear test device was used to check the wear behavior of the piston rings. In the end, an attempt was made to investigate the relationship between properties and tribological behavior created in piston rings. The high hardness and the presence of graphite as a solid lubricant were among the most important factors for the appropriate wear behavior of the piston ring with a diamond-like carbon coating. Due to the lack of complexity and high hardness, the piston ring with hard chromium coating has a sticky wear mechanism and does not show proper wear behavior. The worst wear behavior was observed in the piston ring sample with chromium coating. Low adhesion to the substrate, low hardness, high roughness and thickness, and single layer can be considered as the most important factors of inappropriate wear behavior of this sample. Also, the results showed that the wear resistance of diamond-like carbon coating is almost four times that of chromium nitride coating and six times that of hard chromium.