Properties and mechanism of ceramizable silicone rubber with enhanced flexural strength after high-temperature

Abstract Ceramizable silicone rubber (SR) composites, which transform into high-strength ceramics at high temperatures, are crucial for fire-resistant applications. This study investigates the synergistic effects of ammonium polyphosphate (APP) and zinc borate (ZB) on the mechanical properties and thermal stability of ceramizable SR composites. The results show that the addition of APP and ZB significantly enhances the flexural strength and thermal stability of the composites at high temperatures, while maintaining their elasticity and electrical insulation properties at room temperature. The synergistic effect of APP and ZB leads to the formation of a liquid phase at high temperatures, which binds the residual materials and promotes the formation of mullite and aluminum borate crystals, resulting in a high-strength ceramic matrix. The composite exhibits excellent elongation at break (492.36%) and electrical insulation (volume resistance of 1.89 × 10 14 Ω m) at room temperature, and a flexural strength of 39.47 MPa after heat treatment at 1,000°C.