Thermal degradation and fire performance of intumescent silicone-based coatings

This paper deals with the thermal degradation and fire performance of silicone-based coatings for protecting steel. In this study, the fire performance of silicone coatings as virgin or formulated materials is evaluated using two homemade fire testing methodologies: one similar to the “torch test” fire testing method and the other using a heat radiator test. It was shown that the performance of the silicone-based coating used as thermal barrier can be improved incorporating a modifier (a mixture of polydimethylsiloxane and silica coated by a silane). In this case, silicone-based coating swells and exhibits same fire performance as commercial intumescent coating at the torch test. It is shown that the incorporation of modifier in the silicone makes it to swell upon heating resulting in the formation of expanded material exhibiting low heat conductivity. Thermal degradation of the coating is also investigated: it occurs in three main steps leading to the formation of a tridimensional network characterized by the formation of Q⁴ structure at high temperature. Copyright © 2012 John Wiley & Sons, Ltd.