Synergistic Modulation of Conductivity and Oxidation Stability in SiHfBCN Ceramics via UV-Assisted Structural Evolution

High-temperature energy systems require robust functional coatings and sensing materials capable of operating under extreme thermal and oxidative environments. The polymer-derived SiHfBCN ceramics system shows strong potential owing to their outstanding thermal stability and oxidation resistance. However, achieving compatibility with high-resolution patterning remains challenging due to the lack of suitable photosensitive precursors. Herein, a photoresponsive quinary SiHfBCN preceramic resin is rationally designed via sequential grafting of acrylate photosensitive units onto the polymer backbone, enabling efficient photolithography and dense ceramic film formation. Compared with conventional thermal processes, UV curing significantly enhances microstructural order and promotes the formation of conductive networks, yielding a low resistivity of 0.087 Ω·m at 1200 °C. Further incorporation of carboxylated multi-walled carbon nanotubes reduces the resistivity to 4.49 × 10⁻³ Ω·m by constructing chemically coupled conductive networks. The ceramic films exhibit a Young's modulus of 93.38 ± 0.50 GPa and a hardness of 9.34 ± 0.09 GPa. Notably, negligible changes in internal resistivity are observed after 50 h oxidation at 1200 °C in air, owing to a self-sealing oxide layer reinforced by carbon nanotube–oxide nano-pinning interfaces. This work elucidates the synergistic roles of UV curing and carbon nanotube incorporation in tailoring phase evolution, electrical transport, and oxidation stability in complex polymer-derived ceramic systems, highlighting the strong potential of photo-induced SiHfBCN ceramic films as integrated conductive and self-sensing coatings for high-temperature energy applications.