抄録
In this paper, the effects of oxidation on thermal debinding process for properties of sintered parts made by MIM (Metal Injection molding) were studied using 4 kinds of copper powders(Gas atomized powder, water atomized powders and flakelike powder). The difference of sintered peoperties with sintering atmosphere(H2, vacuum) was investigated. The scale of oxidation of powders in air related to the binder removal, impurity oxygen content and specific surface area of powders. Copper oxides(Cu2O, CuO) formed on surface of particles during debinding process were reduced in H2 at 500°C, but which presented inside particles was remained and influenced densification of parts. The density of sintered parts at 980°C in Ha and vacuum was influenced by the scale of oxidation of powders. Sintered density tended to be low with increasing the scale of oxidation of powder, independently of sintering atmosphere. Residual oxygen content decreased with increasing sintered density and decreasing the scale of oxidation of powders. These tendencies were remarkably appeared with flakelike powder, but hardly with the other powders. In comparision with sintering properties in Ha and vacuum, sintered density and residual oxygen content of sintered parts had little difference.
