| 摘要 |
PURPOSE:To obtain a piston ring having excellent wear resistance, solid lubricity and gas sealability by forming a compd. layer of Al3Ni2 and AlNi on the sliding surface of a piston ring made of a Ni-resist cast iron used for an Al alloy piston body. CONSTITUTION:The piston rings 3 of the piston 1 of an engine provided with compression rings 3a and an oil ring 3b to the Al alloy piston body 2 are made of the Ni-resist cast iron having the coefft. of thermal expansion equal to the coefft. of thermal expansion of the piston body 2 so that the set value of the groove clearances between the rings 3 and the ring grooves can be set as small as possible. The compd. layer in which the AlNi having the excellent resistance to heat, wear and corrosion and the Al3N2 having the excellent solid lubricity mixedly exist is formed by a low-temp. aluminum pack treatment to about >=5mu, more preferably about >=10mu on at least the sliding surface of the rings 3 with the piston. |
