| 摘要 |
PURPOSE: To obtain sintered parts having excellent mechanical characteristics in a short binder removing time without using costly iron powders by composing the above compsn. of a binder consisting of reduced iron powder and specific components. CONSTITUTION: This compsn. is prepd. by kneading the binder components consisting, by weight%, of 1 to 2 polystyrene, 1 to 2 acrylic resin, 0.5 to 1 polyethylene, 1.5 to 2.5 paraffin and 0.5 to 1 stearic acid and the reduced iron powder for the balance. Such compsn. is injection molded in metal molds and is formed to a preform, which is then heated at a temp. below the m.p. of the reduced iron power and is thus subjected to the binder removing treatment; thereafter, the molding is subjected to a sintering treatment, by which the sintered parts are obtd. The reduced iron powder is obtd. by subjecting iron oxide to reduction by heating, then to decarburization refining followed by annealing. The reduced iron powder having an average grain size of 6.0 to 11.0μm and a specific surface area of 0.30 to 0.80m<2> /g is more preferable for averting the increase in the viscosity at the time of injection molding by the increase in the specific surface area and the degradation in the mechanical characteristics of the sintered parts by the increase in the particle size.
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