ABSTRACT Although silicone rubber‐based thermal protective coatings are widely used in the thermal protection field due to their outstanding properties, their inherent drawbacks of low mechanical strength and char residue require synergistic regulation via matrix modification and filler optimization. In this study, short‐cut high‐siloxane fibers (HSiF) and short‐cut aramid fibers (AFs) were used as ablation‐resistant fillers, and phenolic hollow microspheres (PF) were co‐filled into silicone rubber to prepare heat‐protective coating materials. A detailed comparative analysis of the properties of the different samples prepared was carried out. The results showed that the addition of both HSiF and AF could improve the residual carbon rate of silicone rubber composites, with HSiF acting more significantly. The residual carbon rate of the composites with 6 phr HSiF increased from 39.14% to 43.45% at 1000°C, and the line ablation rate and mass ablation rate decreased by 28.1% and 39.8%, respectively. The addition of AF also enhanced the ablation resistance, but the effect was relatively weak, and the line ablation rate and mass ablation rate of the composites with 6 phr AF decreased by 2.5% and 30.6%, respectively. This study provides insights for the development of silicone rubber composites in thermal protection applications.
Zhang et al. (Fri,) studied this question.