Influence of forming technique on the SiC-platelet orientation in a liquid phase sintered SiC-matrix

The alignement of SiC- platelets and the effect on densification of a liquid phase sintered silicon carbide composite were studied. Dry pressing and thermoplastic forming techniques (injection moulding, thermoplastic extrusion and hot moulding) were used to shape test bars, rings, disks, tubes and balls. Corresponding to the flow of the mixtures an alignement of the platelets was observed. In some shapes there was a perfect alignement of the platelets preventing the formation of a platelet framework and resulting in high sintering densities of > 97 percent th.D. with 20 percent platelet content. It essentially demonstrates the opportunity of making dense platelet reinforced composites by pressureless sintering.