Vat photopolymerization of complex-shaped silicon nitride ceramics with high mechanical and thermal performance by optimization sintering aids and kinetics

In this study, the impact of sintering aid content and sintering time on the density, phase composition, microstructure, thermal conductivity, and mechanical properties of silicon nitride (Si₃N₄) ceramics through vat photopolymerization (VPP) was systematically investigated. The results revealed that an increase in sintering aid amount promoted the network distribution of the grain boundary phase along with densification, grain coarsening and microstructure uniformity. The extension of sintering time improved density, thermal conductivity, and mechanical properties of the material. Superior performance with relative density of 99.4 %, thermal conductivity of 64.4 W·m⁻¹·K⁻¹, flexural strength of 879 ± 37 MPa, and hardness of 15.0 ± 0.4 GPa was achieved in sample containing 8 wt% MgO/Y₂O₃ sintered for 12 h. Finally, high-precision Si₃N₄ ceramic heat sink elements were successfully fabricated via VPP, opening up new prospects in thermal management applications associated with electronics and automotive industries.