Abstract: Silicon nitride (Si₃N₄) honeycombs are gaining increasing attention due to their high specific strength, excellent dielectric properties, and superior heat resistance. However, producing Si₃N₄ honeycombs with complex geometries and precisely controlled pore structures remains a significant challenge. This study successfully fabricates eight types of Si₃N₄ honeycomb ceramics with intricate designs using vat photopolymerization (VPP) technology. To enable these advanced structures, a slurry with enhanced curing depth was developed by hydroxylating Si₃N₄ powders and incorporating a highly reactive photosensitive resin, achieving a curing depth of 120 µm. The viscosity of the slurry decreased from 1782.17 to 0.70 Pa s as the shear rate increased from 1 to 100 s^âˆ'1, with no noticeable sedimentation observed after 30 days. The study also investigates the failure mechanisms and mechanical properties of the different honeycomb structures. It was found that the failure modes were closely linked to their cell structure, with re-entrant, triangular, and square honeycombs exhibiting exceptional compressive properties. Notably, the re-entrant honeycomb demonstrated superior compressive strength, elastic modulus, energy absorption, specific energy absorption, and specific strength of 453.8 ± 41.6 MPa, 7.7 ± 0.8 GPa, 14.4 ± 1.3 kJ, 6.6 ± 0.4 kJ kg^âˆ'1, and 210.2 ± 18.6 MPa cm³g^âˆ'1, respectively. The results indicate that the re-entrant structure, with its negative Poisson’s ratio, benefits from an interplay of strut deformations that delay failure, enhancing the overall structural strength. This work highlights the potential of VPP 3D printing to fabricate Si₃N₄ ceramic honeycombs with sophisticated structures and controllable pore geometries. It offers valuable insights into the mechanical properties and failure behaviors of different honeycomb designs, providing a foundation for the future design and application of Si₃N₄ honeycomb ceramics.

Key words: Additive manufacturing, Honeycomb structure, Si₃N₄ ceramics, Compressive strength, Energy absorption