Synthesis of 30 wt%BAS/Si3N4 composite by spark plasma sintering

30 wt%BAS/Si3N4 composite was fabricated via spark plasma sintering (SPS) process. The as-sintered specimens were subsequently heat-treated at 1800 °C to further optimize the microstructure and mechanical properties. The results show that SPS could effectively promote the reaction synthesis of BAS glass and α- to β-Si3N4 phase transformation, resulting in a dense 30 wt%BAS/Si3N4 composite with fine elongated β-Si3N4 grains dispersed in the continuous BAS glass matrix. Post heat-treatment could realize the complete crystallization of BAS and microstructural optimization. The obtained composite exhibits excellent mechanical properties compared to unreinforced BAS glass–ceramic. The flexural strength and fracture toughness could reach 944 MPa and 8.9 MPa m1/2, respectively, which reach the level of conventional Si3N4 composites sintered by traditional sintering process. SPS followed by heat-treatment provides a feasible way to control microstructure, thus optimizes the mechanical performance of glass–ceramics matrix composites.