| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston ring that does not eliminate a recessed part in a surface even when abrasion on a sliding surface progresses, can keep good seizing resistance, and has abrasion resistance and separation resistance better than those of a conventional piston ring having a porous chrome plated layer. SOLUTION: This piston ring includes a laminated layer hard Cr plated layer having a plurality of hard Cr plated layers on an outer peripheral surface, a micro crack is formed on each hard Cr plated layer, the micro crack on hard Cr plated layers other than the outermost hard Cr plated layer forms a micro cavity independently in the coating direction. A surface area ratio of the micro cracks on the hard Cr plated layer is 0.5-5.0%, and number of the micro cracks is 50-1200/10 mm.
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