Composite chromium plating film and sliding member covered thereof

摘要

A piston ring formed with a nitrided layer over all surfaces and formed with a composite chromium plating film over the nitrided layer in the outer circumferential surface. The composite chromium plating film has a network of cracks formed on the outer surface and interior. Si3N4 particles are fixed in these cracks. The average size of the Si3N4 particles is 0.8 to 3 mu m and the dispersion ratio of the Si3N4 particles is 3 to 15 percent by volume.