Kobe Steel, Ltd.

Hiroaki Nii

Kenji Yamamoto

Naofumi Kanei

Hirotaka Ito

Maiko Abe

Tomohiro Otsuka

A piston ring includes a first ring portion which is fitted onto an outer circumferential portion of a piston and which is capable of sliding relative to an inner wall surface of a cylinder, and a second ring portion which is fitted onto the outer circumferential portion of the piston, arranged side-by-side with the first ring portion in the axial direction, and which is capable of sliding relative to the inner wall surface of the cylinder. The second ring portion is fitted onto the outer circumferential portion of the piston in such a way as to be positioned on a side opposite to a compression chamber inside the cylinder, relative to the first ring portion, and has a greater hardness than the first ring portion has.

Piston ring and compressor

A laminated hard coating comprising a layer A and a layer B, wherein the layer A and the layer B differ in composition and are laminated. Layer A contains (MAlCrTa)(BCN) and satisfies 0&#x2264;a&#x2264;0.35, 0.05&#x2264;d&#x2264;0.35, 0&#x2264;x&#x2264;0.15, 0&#x2264;y&#x2264;0.50, a+b+c+d=1, and x+y+z=1. M is at least one element selected from the group consisting of V, Nb, Mo, and W; a, b, c and d represent the atomic ratios of M, Al, Cr, and Ta, respectively; and x, y, and z represent the atomic ratios of B, C and N, respectively. The layer B comprises (TiSi)(BCN) and satisfies 0.05&#x2264;&#x3b2;&#x2264;0.35, 0&#x2264;x&#x2264;0.15, 0&#x2264;y&#x2264;0.50, &#x3b1;+&#x3b2;=1, and x+y+z=1. &#x3b1; and &#x3b2; represent the atomic ratios of Ti and Si, respectively, and x, y, and z represent the atomic ratios of B, C, and N, respectively. One or more layers of each of these layers have been alternately laminated.

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Kobe, Japan

Hiroaki Nii