Patent ID: 8240676

Claim:
A piston ring comprising: a piston ring main body; and a surface coating film on at least one of i) an upper surface and a lower surface of the piston ring main body, wherein, the surface coating film comprises heat-resistant resin and copper based powder contained therein, a rate of content of the copper based powder in the whole of the surface coating film is between 20 and 80% by mass, the copper based powder is any of the group consisting of pure copper, copper oxide, and copper alloy, the copper based powder has a scale shape in powder and an average diameter particle thereof is between 8 and 12 μm, the heat-resistant resin includes a solid lubricant comprising one selected from the group consisting of molybdenum disulfide, tungsten disulfide, and graphite, a rate of content of the lubricant in the whole of the surface coating film is between 2 and 10% by mass, and the copper based powder is accumulated in a thickness direction of the surface coating film.