| 摘要 |
PROBLEM TO BE SOLVED: To increase a coefficient of friction and to improve wear resistance by regulating the porosity of a sintered friction material, prepared by solidifying a raw- material powder composed essentially of copper, to a value in a specific range. SOLUTION: The porosity of the coppery sintered friction material is regulated to 35 to 60%. By this method, the increase in a friction coefficient can be made effective by the permeation of lubricating oil existing in the contact interface between a friction material and a mating material and the increase of contact area due to reduction in rigidity. This material has hard grains and a copper alloy matrix as the balance of them, and the hard grains are contained by 5 to 40% by weight and the copper alloy matrix as the balance has copper or copper alloy, lubricant, and inevitable impurities. As the hard grains, a ferrous intermetallic compound is particularly preferred from the view point of an increase in friction coefficient and excellent machinability. Further, it is preferable to regulate the average grain size of the hard grains to <=20μm. Material powders are mixed into a prescribed composition, and the resultant powder mixture is press-compacted in a die and also pressurized under electrification, and the resultant sintered compact is heat treated at 700 to 1,000 deg.C.
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