Sintered composite machine part and manufacturing method thereof

A method of manufacturing a sintered composite machine part comprising:

• a main body being composed of sintered porous iron alloy and having airtightness;
• and a sliding part being composed of sintered porous copper alloy and being bonded direct to the main body, the method comprising:
• preparing the main body being composed of sintered porous iron alloy and having one of a projection and a depression that are engaged with each other;
• preparing a green compact for the sliding part, the green compact having a shape corresponding to the sliding part, having the other of the projection and the depression and having a plurality of axis-symmetrically formed notches on the outer circumference thereof, and being formed of a raw material metal powder having a composition substantially corresponding to said copper alloy;
• contacting tightly the green compact for the sliding part with the main body, and engaging the projection and the depression with each other to position the green compact for the sliding part to the main body;
• heating the green compact for the sliding part in contact with the main body to a temperature lower than the temperature that copper melts, thereby sintering the green compact for the sliding part to produce the sliding part and occurring diffusion of metal to bond the sliding part to the main body;
• and
• subjecting the main body bonded to the sliding part to steam treatment to provide an iron oxide layer on the surface of the main body, thereby imparting airtightness to the main body.