| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylinder block in which any etching treatment or post- treatment of etching solution is unnecessary, surface roughness can be fined, friction characteristic can be improved, piston sliding resistance is reduced, an excellent oil film can be formed because reinforcing material of the bore surface is porous, and oil holding property can be improved. SOLUTION: In this cylinder block, the reinforcing material 4 formed of porous metal is compounded on the metal matrix in which at least a cylinder bore sliding part 3 forms the cylinder block 1. The surface roughness Rz of the cylinder bore sliding part 3 is 1 to 6μm, the reinforcing material 4 is dispersed in a mesh-like or island-like manner in the metal matrix with the shorter length thereof in a range of 10-500μm, and protruded by a predetermined quantity inwardly in the bore diameter direction from the metal matrix surface.
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