IRON-BASE POWDER MIXTURE FOR POWDER METALLURGY HAVING EXCELLENT FLUIDITY AND MOLDABILITY AND PROCESS FOR PREPARING THE SAME

摘要

An iron-base powder mixture for powder metallurgy which exhibits enhanced fluidity and moldability when heated to about 423 K and filled into a mold for molding is prepared by adding a surface modifier to an iron-base powder and an alloying powder, conducting primary mixing to prepare an iron-base powder mixture, adding at least one member selected from the group consisting of fatty acid amides, metallic soaps having higher melting points than the fatty acid amides, thermoplastic resins, thermoplastic elastomers, and inorganic and organic compounds having lamellar crystal structures to the iron-base powder mixture to conduct secondary mixing, agitating thereafter the mixture while heating to at least the melting point of the added amide to melt the amide, cooling the mixture while mixing the same to adhere the alloying powder and the lubricant having a higher melting point than the amide onto the surface of the iron powder by taking advantage of the binding force of the melt, and adding thereto, during cooling, at least one member selected from the group consisting of metallic soaps, thermoplastic resin and thermoplastic elastomer powders, and inorganic and organic compounds having lamellar crystal structures to conduct tertiary mixing.