Densification on the Capsule Free Sinter-Hipping with Timing of Pressurizing after Onset of Heating.

In this study, densification process of the capusle free sinter-Hipping was investigated by using Al2O3 experimentally. In green compact with many pores, it is known that the densification of capsule free sinter-Hipping is inhibited when these pores in the inside has been connected with the surface and pressurization gas invades into the pores. Then, for the samples which carried out pressureless pre-sintering using electric furnace at 1100°C, the densification process was traced by measuring the density of the samples at any times of capsule free sinter-Hipping process which was pressurized after the onset of heating. As the results, though the increase of relative density to about 58% was very slightly, the rate of densification was rapidly improved to the end of heating up after it and was lowered during the temperature holding process.