| 摘要 |
PROBLEM TO BE SOLVED: To reduce the costs of manufacture, and reduce abrasion by plating covering metal having hardness lower than that of a compound layer with a specified thickness on the compound layer. SOLUTION: A piston ring 1 is made of cast iron, and nitride layer is formed on the whole of an outer peripheral surface of the piston ring 1 or its surface. The layer consists of a dispersion layer 2 and a compound layer 3 whose thickness is about 15μm and which is very hard and weak. A very thin layer 4 made of non-ferrous metal is covered on the compound layer 3 with the thickness of 5μm and less by means of electric plating. A material having a perlite type foundation texture and spherical or helminth shaped graphite precipitation particle is suitable as the cast iron, and is suitable to a high temperature load. It is thus possible to eliminate mechanical treatment completely, and it is also possible to form an optimal contact surface on a piston ring surface.
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