Preparation of C _f /Si ₃ N ₄ composites based on vat photopolymerization combined with precursor infiltration and pyrolysis

Abstract The development of vat photopolymerization (VPP) 3D printing technology has created the conditions for the fabrication of complex structured Si 3 N 4 ceramics. However, Si 3 N 4 ceramics produced through VPP often lack sufficient mechanical properties, which limiting their applications. This study introduces short carbon fibers (C f ) into the VPP‐Si 3 N 4 ceramics, combined with the polymer infiltration and pyrolysis (PIP) process, to prepare C f /Si 3 N 4 composites. The effect of C f content on slurry preparation, green part printing, and mechanical properties of the C f /Si 3 N 4 composites was systematically investigated. The results indicate that C f significantly enhances the mechanical properties of C f /Si 3 N 4 composites. At 6 wt.% C f content, the samples exhibit the highest strength and fracture toughness, reaching 183.2 MPa and 6.2 MPa·m 1/2 , respectively, representing increases of 29.7% and 92.3% compared to samples without C f . The improvement in mechanical properties is partly due to the ‘pinning effect’ of C f , which enhances interlayer bonding strength in the printed green parts, positively impacting the overall mechanical properties of the composites. Additionally, inherent toughening mechanisms of C f , such as fiber pull‐out, crack deflection, and crack bridging, further enhance the composite's mechanical properties. This study confirms the feasibility of using C f to enhance the mechanical properties of VPP‐Si 3 N 4 ceramic.