Influence of carbon on sintering of the Al-Si-C-N system composite

The composite in Al4SiC4-AlN and Al4SiC4-AlN-C system were sintered by a spark plasma sintering method. The powders of metal Al, Si and carbon black and AlN as starting materials were mixed. The mixture was calcined at 1300 degrees C and sintered at 1600 degrees to 1800 degrees C by spark plasma sintering. Shrinkage during sintering, density, microstructure and phase of sintered bodies were measured. X-ray diffraction analysis gave Al5SiC4N (15R) and AlN (2H) phases in the bodies sintered at 1750 degrees C. Densification did not occur in some composition in 50 to 80% AlN of the system Al4SiC4-AlN, but their densification was accelerated by addition of carbon. By the analysis of shrinkage during sintering and SEM observation of microstructure, the grain of Al5SiC4N (15R) and AlN (2H) grew, and pore exclusion was obstructed in the system Al4SiC4-AlN, though the grain did not grow, and pore exclusion was accelerated in the system Al4SiC4-AlN-C.