Influence of pore structure in green compacts on the densification of SiCAl 2O 3Y 2O 3

Abstract

Pore size, pore size distribution (PSD), and the resultant densification behavior of α-SiC granular compacts, which were shaped under the uniaxial compaction pressure of 6.8–154 MPa, were investigated. Three kinds of SiC granules were used, namely Powder R (as-received spray-dried granules), Powder C (after classification of the Powder R), and Powder G (after grinding of the Powder R). Experimental results showed that at low compaction pressures, the green compacts derived from Powder R and Powder C exhibit a bimodal PSD, which is primarily caused by the presence of intergranular porosity. At relatively high compaction pressures, all of the green compacts display a roughly similarly unimodal PSD and exhibit a similar densification behaviour regardless of the starting granule characteristics. The green compacts with a narrow and unimodal PSD can be easily densified to a high-density sintered body and this behaviour was particularly pronounced for the green compacts derived from the ground granules even when the applied compaction pressure is relatively low.