抄録
This study aims to make clear the mechanism of heterogeneous sintering, where the sintering is more delayed in the near surface of the material compared to that of the interior. This phenomenon is unique in metal injection molding. The mixed slurry with 93wt% SUS304 steel powders with mean dia. of 11.2μm and 7 wt% binder were subjected to the injection at 150°C, followed by isothermal debinding in air at temperatures of 250-300°C, then vacuum sintering isothermally at 1000-1300°C. During sintering. more amount of retained binder contained carbon in the near surface causes to generate higher vapor pressure of CO gas, implying that this results in delayed sintering because of the higher pressure which prevails against the reduction forces of necks, voids, or pores, whereas in the material interior, the vapor pressure is lower than the reduction forces.
