Microstructures and properties of Si3N4/TiN composites sintered by hot pressing and spark plasma sintering

Abstract Microstructures and mechanical properties of the Si 3 N 4 /TiN composites sintered by hot pressing (HP) and spark plasma sintering (SPS) were studied comparatively. Compared with the non-conductive monophase Si 3 N 4 ceramic which has lower density and α – β transformation ratio prepared by SPS than by HP, the conductive Si 3 N 4 /TiN composite sample, however, has higher density and obviously higher α – β transformation ratio sintered by SPS than by HP, which means that the presence of TiN clearly improves the densification and α – β phase transformation of silicon nitride in SPS compared in HP. The microstructure analysis shows that the SPSed Si 3 N 4 /TiN composites had lower porosity and aspect ratio than the monophase Si 3 N 4 . Both the hardness and fracture toughness of the Si 3 N 4 /TiN composite with 50%TiN sintered by SPS are higher than by HP, but the hardness and fracture toughness of the non-conductive monophase Si 3 N 4 ceramics do not have a significant difference either sintered by SPS or HP.