Vat photopolymerization of hierarchical TPMS SiC ceramics: tunable heat transfer via gradient porosity and checkerboard design

This study explores the additive manufacturing (AM) of silicon carbide (SiC) ceramics featuring gradient triply periodic minimal surface (TPMS) architectures fabricated using vat photopolymerization, a high-resolution AM technique. We systematically evaluate the thermal performance of three TPMS topologies – Schoen gyroid (38 mm pores), Neovius surface (20 mm), and Schwarz diamond (14 mm) – under varying hotspot dimensions (1.5–2.5 cm). Results demonstrate that gradient TPMS configurations significantly improve thermal resistance by modulating porosity distribution while maintaining structural volume. Specifically, the Schoen gyroid achieves optimal thermal insulation at 1.5 cm hotspots, stabilising surface temperatures at 250°C, whereas the Schwarz diamond minimises conductive losses at 2 cm hotspots, reducing temperatures to 280°C. Sintering-induced defects, including gas-entrapped bubbles and stress-driven cracks, are identified as critical disruptors of heat transfer pathways in larger hotspots (2.5 cm), causing localised temperature deviations. To address this, we propose a hierarchical checkerboard design integrating in-plane Schoen gyroid layers (for radiative-dominated 1.5/2.5 cm hotspots) and cross-plane Schwarz diamond layers (for conduction-critical 2 cm hotspots). This hybrid configuration adaptively confines heat flux through synergistic insulation mechanisms. Collectively, this work establishes a defect-mitigated design paradigm for TPMS-based SiC ceramics, advancing their utility in aerospace thermal protection systems subjected to heterogeneous thermal loads.