| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston ring in which tension in a low temperature-low load state and tension in a high temperature-high load state can be changed, thus a friction loss is suppressed to the minimum, and the improvement of fuel consumption is made possible. SOLUTION: The piston ring is formed of a shape memory alloy comprising nickel of 34.7 to 48.5 mol%, at least either zirconium or hafnium of 9 to 22.5 mol%, niobium of 1 to 30 mol%, and the balance titanium with inevitable impurities. COPYRIGHT: (C)2008,JPO&INPIT
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