Resistance to fire of silicone-based coatings: Fire protection of steel against cellulosic fire

Abstract

The fire performance of curable silicone-based coatings containing expandable graphite, organoclay, and calcium carbonate is evaluated in cellulosic fire scenario (standard ISO834) using a lab-scale furnace test. It is shown that the use of organoclay and calcium carbonate allows achieving same insulative performance when compared with organic commercial intumescent coating. The mode of action of these silicone-based coatings is fully investigated using thermal analyses and spectroscopic analyses including X-ray photoelectron spectroscopy. It is shown that the high fire performance of intumescent silicone-based coatings is due to (1) interactions between calcium carbonate and silicone matrix increasing the thermal stability of the resin and (2) the formation of calcium silicate embedding the top of the char and permitting the formation of an additional protective ceramic layer.