Synergistic Design of High-Emittance Ceramicizable B4C-LaB6/Silicone Rubber Thermal Protection Coatings and Their Ultra-High-Temperature Ablation-Radiation Coupling Mechanism

Aerodynamic heating threatens hypersonic vehicles, making lightweight, flexible thermal protection coatings essential. This paper designs and prepares a multifunctional B 4 C-LaB 6 /silicone rubber high-emissivity ceramicizable thermal protection coating. By incorporating chopped high-silica silica fibers and aramid fibers as ablation-resistant fillers into the silicone rubber matrix, and combining them with the high-emissivity functional components B 4 C and LaB 6 , a coating material with both ablation protection and radiative heat dissipation capabilities was achieved. Research indicates that the synergistic effect of B 4 C-LaB 6 significantly enhances the thermal stability and thermal insulation performance of the composite coating: At a B 4 C:LaB 6 ratio of 20:20, the coating's mass retention rate at 1000°C increased from 43.45% to 80.68%, with an average infrared emissivity reaching 0.947. Concurrently, the coating exhibited lower linear ablation rates and a denser ceramic layer structure. This research offers new insights for multifunctional silicone rubber thermal protection coatings, showing potential for hypersonic vehicles. Highlights The B 4 C-LaB 6 system significantly improves the thermal stability of silicone rubber composites. The B 4 C-LaB 6 system densifies the ceramic layer during high-temperature ablation. The B 4 C-LaB 6 system achieves high near-infrared emissivity. The B 4 C-LaB 6 /silicone rubber coating demonstrates a multifunctional design for thermal protection materials.