Effect of Sintering Temperatures on the Reaction-Bonded Si3N4/SiC Composite Ceramics

Effect of sintering temperatures on reaction-bonded Si3N4/SiC composite ceramics under pressureless was investigated. Si3N4/SiC composite ceramics were sintered at different temperatures from 1450 to 1700 °C under nitrogen atmosphere by using SiC with different particle sizes, Si and additives Y2O3 as raw materials. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive strength tests. The results demonstrated that when the particle gradation consists of silicon carbide of 74 μm (5 wt.%), 44 μm (10 wt.%) and 0.5 μm(35 wt.%) and silicon powder of 74 μm (42 wt.%), the more dense samples with the bulk density of 2.43 g/cm3 and the higher compressive strength of 324 MPa could be obtained at the sintering temperature of 1550 °C for 3h as the optimum processing parameters.