Piston ring and piston device

摘要

A piston ring which can sustain a superior effect of preventing aluminum cohesion for a long time in a high output engine is provided. At least one of the upper and lower side faces of a piston ring is coated with a polyimide film having hard particles dispersed therein. Employed as the hard particles may be alumina, zirconia, silicon carbide, silicon nitride, cubic boron nitride, or diamond. The hard particles are to be 0.01 to 5 μm in average particle diameter, and the film is 2 to 30 μm in thickness.

主权项

1. A piston ring having at least one of upper and lower side faces coated with a film, wherein the film is a polyimide film containing hard particles,
the hard particles have an average particle diameter of 0.01 to 5 μm, and the film has a hardness HV at 250° C. of 30 to 70 which falls within a range of ±40% of a piston hardness at 250° C.