To solve a problem in which it is necessary to form a plurality of fine oil sump portions in the sliding surface of a sliding member in the sliding member excellent in abrasion resistance with another material compounded into a foamed metal member and lubricating oil easily flows in a peripheral direction in streaks in a structure for forming many streaks extending in the peripheral direction in the peripheral surface of the skirt part of a piston.
In the reciprocating engine piston formed by using aluminum alloy as base material, the foamed metal member 4 comprising Fe or Ni as a main component is inserted into the surface layer portion of a part of the skirt portion of the piston and compounded with the aluminum alloy, a plurality of streaks extending in the peripheral direction and mutually separated is formed in the surface of the skirt, a chemical conversion coating film 8 is formed on the whole surface including a compounded portion 4A, a chemical conversion coating film 8b on the surface of the foamed metal member 4 is set to have thickness about 3 to 5 times thicker than a chemical conversion coating film 8a on the surface of an aluminum alloy portion 5, and many fine oil sump portions are formed by the chemical conversion coating film 8b.
SAKATE NOBUO
UOSAKI YASUO
SHIBAHARA MASAHIKO
WAKASAKI AKIO
KADOSHIMA SHINJI
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