Structural optimization and mechanical property enhancement of MgSiN ₂ ceramics: Strategy of interface strengthening

Abstract In this study, dense MgSiN 2 ceramics were successfully fabricated for the first time using SPS technology. The effects of Y 2 O 3 sintering additives and sintering temperature on the densification mechanism and mechanical properties of the ceramics were systematically investigated. Results indicate that Y 2 O 3 enhances the mechanical properties of MgSiN 2 ceramics through the formation of the secondary phase Y 2 Si 3 O 3 N 4 at 1300°C. When the sintering temperature exceeds 1400°C, Y 2 Si 3 O 3 N 4 transforms into an amorphous phase. A robust interfacial bond forms between the amorphous phase and the MgSiN 2 matrix, promoting both material densification and the coalescence and growth of MgSiN 2 grains. The synergistic effect of strong interfacial bonding and grain growth markedly improves the densification and mechanical properties of MgSiN 2 ceramics. Notably, MgSiN 2 ceramics containing 1 mol% Y 2 O 3 prepared at 1400°C exhibit bending strength and fracture toughness values of 477.2 MPa and 5.3 MPa·m 1/2 , respectively, with a high relative density of 99.3%.