Preparation of rare earth Nd2O3 synergistic toughening Si3N4 ceramics by low temperature pressure-less sintering

This study used YAG and MgO as composite sintering aids, Nd 2 O 3 doped Si 3 N 4 ceramics were successfully fabricated at 1620 °C using pressure-less sintering. The results demonstrate that an appropriate amount of Nd 2 O 3 significantly enhances the mechanical properties of the material. At a doping level of 6 wt.%, the fracture toughness,hardness and flexural strength were 13.59 ± 0.30 MPa·m 1/2 , 18.41 ± 0.21 GPa and 796.6 ± 46.65 MPa. Phase and microstructural analyses reveal that α-Si 3 N 4 has been largely transformed into β-Si 3 N 4 , accompanied by the formation of rod-like grain morphology. This research confirms that YAG can serve as an effective sintering aid, and when combined with Nd 2 O 3 doping, high-toughness Si 3 N 4 ceramics can be obtained under pressure-less sintering conditions. The findings provide a solid research foundation for the application of Si 3 N 4 ceramics in engineering and defense-related fields.