Optimization of spark plasma sintering parameters of Si3N4-SiC composite using response surface methodology (RSM)

The Si3N4-SiC micro-nano composites were fabricated via the spark plasma sintering method using MgSiN2 as an additive. Response surface methodology and central composite design were applied to optimize the spark plasma sintering process for the fabrication of Si3N4-SiC/MgSiN2 with improved density. The relation between the three parameters of sintering including temperature, pressure, and holding time was modeled and the optimized parameters were obtained. The best sintering results obtained for the sintering temperature, holding time, and pressure are 1700 °C, 487 s, and 49 MPa, respectively. The addition of MgSiN2 as an additive and SiC as a secondary phase were also investigated in the present work. The Si3N4−5 vol% SiC composite exhibited high hardness (19 GPa) and fracture toughness values (6.5 MPa m1/2) at room temperature.