| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston ring combining scuffing resistance and wear resistance. SOLUTION: On the whole surface of a piston ring 1, a gas-nitriding layer 2 is formed, and on the gas nitriding layer 2 of the outer circumferential face, a hard coating 3 is formed in a thickness of 0.5 to 10μm. The hard coating 3 is formed of diamondlike carbon in which the carbides of one or >= two elements selected from the group of Si, Ti, W, Cr, Mo, Nb and V are dispersed. The diamondlike carbon has any form among 1. an amorphous carbon structure, 2. an amorphous carbon structure partially having a diamondlike structure and 3. an amorphous carbon structure partially having a graphite structure. The contents of the above elements lie in the range of, by atom, 5 to 40%, and the hardness of the hard coating 3 lies in the range of 700 to 2000 HV. In stead of the gas nitriding layer 2, Cr plating coating or ion plating coating 4 may be used. The hard coating 3 may be formed directly on the outer circumferential face of the piston ring 1 in a thickness of 10 to 30μm.
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