RAW MATERIAL FOR POWDER METALLURGY AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To improve the fatigue strength, impact resistance, wear resistance and reliability by incorporating alumina powder with the oversize of a screen having specified openings into the raw material in a specified weight ratio. SOLUTION: The oversize is controlled to be <=0.01 wt.% when alumina powder is screened by the use of a screen having 30μm openings, and 0.5-10 vol.% alumina powder is incorporated. The average grain diameter of the alumina powder is preferably adjusted to 1.5-10μm, and the powder having <=1.5μm and >=10μm grain diameters is controlled to be <=10 wt.%. The average grain diameter D50 (by laser diffraction method) should be 1.5-10μm. The water content of the alumina powder is preferably adjusted to <=0.15 wt.% based on the alumina powder and the water content in the alumina powder plus aluminum alloy powder to <=0.1 wt.%.