Self-Catalytic Ceramicization in Transparent Ablation-Resistant Organosilicon–Boron Coatings for Advanced Fire Protection

The high-quality preservation of precious cultural artifacts requires advanced coatings with stringent demands for transparency, mechanical robustness, and ablation resistance. However, achieving an optimal balance among these performances remains a formidable plight. In this work, we propose a strategy for the synergistic self-catalytic ceramicization of an organosilicon-boron dual-network structure to address these challenges. High-transparency, ablation-resistant silicone-boron fire-retardant coatings were prepared via sol-gel processing using triethyl borate and trimethoxysilane. These coatings achieved remarkable mechanical properties with a level of 9H and flexibility characterized by a bending diameter of ≤2 mm, while maintaining a light transmittance of up to 99.9%. They also exhibited excellent adhesion to diverse substrates including glass and ceramic. The coatings effectively protected substrates from fire, achieving an UL-94V-0 rating and a limiting oxygen index of up to 35.5%. Upon exposure to a high-temperature flame, the coatings rapidly formed a compact ceramic barrier layer on the substrate surface, demonstrating outstanding ablation resistance. Furthermore, this study elucidated the mechanisms underlying the unique combination of toughness, transparency, and flame-retardant ablation resistance in silicone-boron coatings: The dual cross-linked network structure enhanced both the hardness and flexibility. Meanwhile, the synergistic catalytic effect of boron and phosphorus (Si/B/P) promoted the formation of a compact cross-linked ceramic network from silicone, effectively blocking heat and flame propagation. This work provides a versatile approach to designing transparent, ablation-resistant coatings for advanced fire protection.