Mechanistic study of a silicon-based intumescent coating system

The performance and working mechanism of a silicon-based intumescent coating system, comprising primarily silicone binder, fumed silica, and sodium silicate particles, were investigated. Water release from sodium silicate particles coupled with softening of the matrix, induced efficient coating expansion. The residual dehydrated silicates underwent ceramification at high temperatures, resulting in the formation of a compact and thermally stable heat barrier composed of SiO2. Optimization of the coating involved adjusting the amount of sodium silicate particles and introducing kaolin. The best-performed formulation, evaluated in a laboratory-scaled electrical furnace under UL 1709 fire scenario, exhibited a critical time of 56 min, which surpassed that of a commercial epoxy-based intumescent coating by 8 min.