Effect of Tungsten Carbide on Densification and Mechanical Properties of Silicon Nitride Ceramics by Spark Plasma Sintering

The high-performance beta-phase silicon nitride ceramics were prepared by spark plasma sintering (SPS) with Al2O3-Y2O3 as a sintering aid. A novel approach was adopted to fabricate the silicon nitride by introducing WC via mechanical ball milling. The effects of tungsten carbide on densification and mechanical properties of silicon nitride ceramics were investigated. The results show that the introduction of tungsten carbide can effectively reduce the activation energy of beta phase precipitation and growth, which promotes the phase transformation of silicon nitride ceramic, and the densification of sintered samples. With the increase of the amount of tungsten carbide, the flexural strength of sintered samples increases from 729 to 1090 MPa, which is increased by 49.5%.