Combustion‐Driven Rapid Synthesis of Multifunctional Porous Si ₃ N ₄ /SiC Ceramics: Synergistic Strength–Toughness and Electromagnetic Wave Absorption

Abstract Porous ceramic materials exhibit broad multifunctional application prospects. However, the inherent conflict between their structural stability and functional properties, particularly under liquid‐phase sintering conditions, presents a significant challenge. Here, a combustion‐driven rapid synthesis strategy is introduced that overcomes this limitation, fabricating porous Si 3 N 4 /SiC ceramics with exceptional multifunctionality. Leveraging the Si─N─C reaction system, this approach simultaneously achieves a hierarchical pore structure, submicron grain morphology, and a uniform nanoscale graphitic carbon coating, establishing a multiscale architecture. This synergistic microstructure optimization yields low shrinkage (3.4% at 79% porosity), remarkable strength–toughness coupling (62.4 MPa and 4.8 MPa·m 1/2 at 69.3% porosity), outstanding thermal stability (>1200 °C in air), and superior electromagnetic (EM) wave absorption (RL min = −70.97 dB). The facile, energy‐efficient (<0.3 h/batch, <$0.7/L) and low‐carbon synthesis route provides a transformative pathway for designing high‐performance multifunctional porous ceramics.