Wear Properties and Scuffing Resistance of the Cr-Al2O3 Coated Piston Rings: The Effect of Convexity Position on Barrel Surface

This work investigates the effect of convexity position of ring barrel surface on the wear properties and scuffing resistance of the Cr-Al2O3 coated piston rings against with the CuNiCr cast iron cylinder liner. The scuffed surface morphology and elements distribution as well as the oil film edge were analyzed to explore the influencing mechanism of the convexity position on the scuffing resistance. The results show that the convexity offset rate on the barrel surface of the ring has no noticeable influence on both friction coefficient and wear loss near the dead points, but a suitable convexity position will result in the improved scuffing resistance. The shape of the barrel face not only affects the worn area on the ring, but also determines the oil film wedge and pressure distribution, consequently influences the scuffing resistance.