Microstructure and mechanical properties of TiN/Si3N4 nanocomposites by spark plasma sintering (SPS)

TiN/Si3N4 nanocomposites were fabricated from β-Si3N4 and TiN nano powders by powder processing routes. The specimens were consolidated at 1600 °C for 3 min by spark plasma sintering, and nearly full densification was obtained in the resulting sintered bulk composites. The TiN phase grows rapidly and a typical twin structure of TiN can be observed in the composites. The grain size and distribution for TiN may affect the electrical resistivity, leading to a pulse current through the sintering compact. The resulting microstructure for the composite containing 10 wt% TiN reveals that grain coarsening behavior for β-Si3N4 based grains is accelerated, and the composite has the highest toughness of 4.9 MPa m1/2 among all these composites. The other composites show nanosized β-Si3N4 based grains with a fracture toughness of nearly 4.2 MPa m1/2.

Research highlights▶ By utilizing spark plasma sintering technique, the microstructural development of Si3N4 based nanocomposites with varying amount of nano TiN addition was demonstrated, and the relationship between microstructure and performance, such as mechanical properties and electrical conductivity, of these TiN/Si3N4 based composites was discussed. ▶ These results enable us to understand the effects of a pulse direct current during sintering and make it possible to control the resulting microstructure and properties of Si3N4 based nanocomposites in spark plasma sintering.