Patent ID: 6508473
Filing Date: 2003-01-21
Classification: C23C,F16J

Abstract:
A piston ring with a nitrided layer on upper and lower surfaces, or on upper and lower surfaces and an inner circumferential surface, of said piston ring, and formed with a hard film by ion plating on an outer circumferential surface and corners formed by the upper and lower surfaces and outer circumferential surface of said piston ring,wherein said nitrided layer having a Vickers hardness of 700 or more is formed on at least one of a portion of said upper and lower surfaces such that said nitrided layer having a Vicker s hardness of 700 or more and said hard film formed by ion plating on said outer circumferential surface and said corners are separated and are not in contact with each other, and wherein a distance between said nitrided layer having a Vickers hardness of 700 or more and said hard film formed by ion plating is within a range from 0.001 to 0.3 mm.