Low-temperature densification by plasma activated sintering of Mg2Si-added Si3N4

In this study, highly dense Si3N4 ceramics with excellent mechanical properties were fabricated using Mg2Si as a sintering additive by plasma-activated sintering at 1400-1500 degrees C. The effects of the sintering temperature and content of Mg2Si on the densification, microstructures, and mechanical properties of the Si3N4 ceramics were investigated. The mechanism responsible for the effect of Mg2Si in the promotion of the sinterability of Si3N4 is discussed. The results showed that the addition of Mg2Si could effectively remove the oxide layers on the Si3N4 particles and form a liquid phase during the sintering, promoting the densification and phase transition of the Si3N4 ceramics. The Si3N4 ceramic sintered at 1450 degrees C with 6.0 wt% of Mg2Si exhibited the maximum strength of 1050 MPa.