| 摘要 |
PURPOSE:To eliminate masking treatment and to provide excellent resistance to scuff and resistance to wear, by a method wherein almite treatment is applied on at least the upper end surface and the side slide surface of a piston, a ring groove surface, and the inner peripheral surface of a piston pin bearing part. CONSTITUTION:In an upper end surface 11a of a piston 11 made of aluminum and a side 11b thereof, an oxidation film 12 by almite treatment is formed on the whole of the inner peripheral surfaces of first and second ring grooves 11c and 11d, an oil ring groove 11e, and the inner peripheral surface of a piston bearing part 11f. Since, as noted above, almite treatment is applied approximately on the whole surface of the exposed surface of the piston 11, during treatment, there is no need to apply masking, and a process can be simplified. In a piston bearing part and the skirt slide surface of a side, wear and scuffing can be effectively prevented from occurring without especially forming a lubricating oil passage.
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