PISTON RING

PURPOSE:To prevent a piston ring and a piston material from being stuck with each other, by providing an outer surface containing a solid lubricant at the upper and lower surfaces thereof to satisfy the initial conformability between the piston ring and the piston material. CONSTITUTION:A skin (base layer) 6 made of 4-3 iron-oxide or the like having 0.5-5mum is formed on each of both upper and lower surfaces of a mother material 2 made of cast iron steel or the like, and an outer surface layer 4 containing molybdenum disulfide is formed thereover so that a pressure ring 1 is obtained. Further, a hard-chrome plated layer 7 is formed to give a barrel face shape to the outer peripheral surface of the pressure ring 1. In this arrangement, the based layer 3 is disposed between the mother material 1 and the outer surface layer 4 to satisfy the adhesion therebetween. Further, the outer surface layer 4 is formed such that solid lubricant particles 5 are dispersed in heat-resistant resin 6. The pressure ring 1 has the outer surface layer 4 on each of upper and lower surface thereof, containing the solid lubricant particles 5, and therefore, it is possible to satisfy the initial comformability between the piston ring and a piston material.