| Abstract Scope |
The fabrication of Si3N4 ceramics typically requires high temperatures (above 1700°C) and prolonged sintering times to achieve densification, resulting in high energy consumption, elevated manufacturing costs. In this work, we proposed a low-temperature rapid spark plasma sintering strategy by introducing fine-grained β-Si3N4 powder with high lattice strain energy as an “additive”. Dense biphasic Si3N4 ceramics, predominantly α-Si3N4, were successfully fabricated at a mechanical pressure of 200 MPa and a temperature of 1300°C, achieving a relative density of 97%. The application of high pressure promoted particle rearrangement and uniform liquid-phase distribution, providing additional driving forces for sintering. The introduction of β-Si3N4 seeds facilitated an in-situ solution-reprecipitation process, enabling rapid densification with minimal liquid phase and without significant grain growth, resulting in nanometer-scale grains. The fabricated Si3N4 ceramics exhibit a desirable combination of high hardness (20.2±0.5 GPa) and excellent fracture toughness (6.7±0.2 MPa·m1/2). |