Explosive Compaction of SiC Ceramic Powder

Abstract

Explosive compaction of ceramic powders, mainly SiC powder, was performed using by cylindrically axi-symmetric direct method. The effects of the type and mass of explosive and the material and construction of compacting container on the compactibilities of ceramic powder have been investigated by means of microhardness test, optical microscopy, scanning electron microscopy and density measurements.
Hardness of specimen compacted by explosive with slow detonation velocity (2.1-2.4Km/s) was higher than that of specimen compacted by explosive with fast detonation velocity (6-7Km/s) because of long shock duration time. In the case of using the former explosive and Cu tube for compacting container, and at the ratio of explosive mass to powder mass (E/M ratio) more than 200, the specific density ratio of the compact reached about 90%. However, hericoidal and radial cracks were formed in the compact because of the convergence of the shock wave and the interference of the reflected waves.
In the explosive compaction of Si3N4 powder, crack was little formed in the compact. This may be ue to the superior thermal properties of Si3N4, such as smaller thermal expansion and higher strength at high temperature.