Si3N4/TiN Ceramic Composites Produced by Hot Pressing

Si3N4/TiN ceramic composites have been prepared by hot pressing in a nitrogen atmosphere using fine Si3N4 and Ti powders and CaO–Al2O3 sintering aids and investigated. The results demonstrate that hot pressing was accompanied by titanium nitridation, yielding titanium nitride with the composition TiN0.9. Reaction between silicon nitride and the sintering aid led to the formation of a Ca-α-SiAlON with the composition Ca0.67(Si10Al2)(N15.3O0.7). In addition to the major phases, calcium aluminosilicate with the composition Ca3Al2Si3O12 was identified. Increasing the percentage of titanium nitride in the composites prepared at a temperature of 1650°C led to an increase in their density and Vickers microhardness: from 3.18 ± 0.03 to 4.33 ± 0.03 g/cm3 and from 17 ± 1.1 to 29.4 ± 0.9 GPa, respectively.