MICROSTRUCTURE OF LIQUID PHASE SINTERED SILICON CARBIDE CERAMICS WITH HIGH FRACTURE TOUGHNESS

By SEM observation and EDX analysis, the relation between the fracture mechanism and the high toughness in the liquid-phase sintered (LPS) SiC ceramic with high toughness was revealed. The effects of two kinds of sintering methods, pressureless (PLS) and hot-pressing (HP), on their microstructure features and the characteristics of fracture mode were investigated. The results show that both the crack-break ways along the grain-boundary and the transgranular fracture were together enable the toughness higher in the PLS specimen, and the crack-break way along the grain-boundary was the key reason for the higher toughness in HP specimen.