| 摘要 |
PROBLEM TO BE SOLVED: To improve sliding characteristic, particularly seizure resistance. SOLUTION: The outside peripheral surface of a piston ring 1 is coated with a hard film 2 by means of arc ion plating. The hard film 2 contains [O] in the form of solid solution in the crystal structures of CrN and Mo2 N and has a composition consisting of, by weight ratio, 40-78% Cr, 3-35% Mo, 3-20% O, and the balance N, and the sizes of respective crystalline grains are regulated to <1μm. Preferred hardness of the film 2 is 1600 to 2500 by Vickers hardness, and preferred film thickness is 1 to 60μm. Moreover, [C] can be allowed to enter into solid solution by 0.5 to 8 wt.% as the alternative to [O], or both of [O] and [C] can be allowed to enter into solid solution under the following conditions: the amounts of [O] and [C] are 3-20 wt.% and 0.5-8 wt.%, respectively; the total amounts of [O] and [C] is <=25 wt.%. |
