Fabrication of Porous Si ₃ N ₄ Ceramics With Complex Architectures by Direct Ink Writing Combined With Combustion Synthesis

ABSTRACT Porous Si 3 N 4 ceramics with complex architectures have attracted extensive interest for structural–functional integration, yet their fabrication remains constrained by energy‐intensive post‐sintering and limited shape complexity. Here, we reported a hybrid strategy combining direct ink writing (DIW) with combustion synthesis (CS) to address these challenges. The rheological mechanism analysis and computational fluid dynamic simulations provide ideal guidance for flowability and shape retention, achieving defect‐free green bodies with lattice structures. During CS, the volume filling ratio (VFR) was further exploited to modulate thermal conditions. As the VFR increased from 40% to 70%, the combustion temperature elevated by approximately 30°C and the liquid‐phase duration was extended, enabling systematic control over the α→β phase transformation and the grain growth of β‐Si 3 N 4 (aspect ratio from 4.3 to 5.8). The resulting ceramics exhibited tailorable compressive strength (8.9–35.2 MPa) and pronounced anisotropy, with failure mechanisms dictated by the underlying strut architecture. This DIW‐CS approach offers a low‐energy, near‐net shaping route for fabricating porous Si 3 N 4 ceramics with tailored microstructures and mechanical performance for advanced applications.