Abstract: To investigate the flame-retardant effect of carbon materials on silicone rubber foam, this study used five different types of carbon materials as flame retardants to prepare flame-retardant silicone rubber foam composites, and conducted a comparative analysis of their comprehensive properties. The results show that: the introduction of carbon materials affects the micromorphology of silicone rubber foam, leading to smaller pore size and pore wall, thereby changing the mechanical properties of the foam; among the five carbon materials, expandable graphite has the least impact on the mechanical properties of silicone rubber foam; compared with other carbon materials, expandable graphite and carbon nanotubes exhibit higher flame-retardant efficiency in silicone rubber foam. When their addition amount is only 1 part, the Limiting Oxygen Index（LOI） of silicone rubber foam can reach 28.0% and 28.2% respectively, and by vertical buring test, the flame retardancy rating can reach FV-0 grade; the silicone rubber foam with expandable graphite added has a high char residue (58.7%) at 900 °C, and its maximum thermal decomposition temperature is also significantly increased, showing good thermal stability; the cone calorimeter test results indicate that the total heat release and total smoke release of silicone rubber foam with expandable graphite and carbon nanotubes added are significantly reduced, which means it has higher fire safety.

Key words: silicone rubber foam, carbon-based materials, flame retardant performance, thermal stability, combustion behavior