In situ preparation of Si3N4–TiN composite by pyrolysis of polytitanosilazane (PTSZ)

Abstract: Si3N4–TiN composite powders were obtained by in situ pyrolysis of polytitanosilazane. Dense Si3N4–TiN composites were prepared by hot-pressing at 1800°C under 20MPa for 2h without sintering additive. Crystallization of amorphous PTSZ powders occurred between 1400 and 1500°C with major phases, α-Si3N4, β-Si3N4, and small amount of phase TiN. Mechanical properties and microstructure of Si3N4–TiN composites were characterized. The results showed that the mechanical strength was 620MPa, the fracture toughness was 7.8MPam1/2 and the Vickers hardness was 8.5GPa. SEM analysis indicated that Si3N4–TiN composite possessed excellent fracture toughness because TiN grains produced by in situ pyrolysis were well dispersed in Si3N4 matrix. [Copyright &y& Elsevier]