Reinforced intumescent char combined with hollow glass microspheres to improve the fire-retardant and heat-insulation properties of fireproof coatings

The intumescent fireproof coatings (IFC) constructed on the surface of steel can effectively delay the heating rate of the steel under the fire environment, so as to strive for a longer time for personnel evacuation. The char layer formed by the traditional IFC has the disadvantages of easy cracking and falling off. In this work, by using insulating filler hollow glass microspheres (HGM), the I (D) /I (G) value of the coating with the best performance decreased from 1.26 to 0.98. The problem of char layer cracking and falling off was solved. Its 10-minute back temperature is only 181 °C, and the heat insulation effect is significantly improved. In addition, the synergistic effect of HGM and flame retardant system endows the coating with better flame retardant properties. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), cone calorimeter (CCT) and laser Raman spectroscopy (LRS) were used to study the mechanism of improved flame retardant and thermal insulation properties. The HGM uniformly distributed in the coating forms a network structure with Si-O-Si bonds as the skeleton at high temperature. This structure connects the char layer, thereby increasing the strength of the expanded char layer. Therefore, the flame retardant and thermal insulation properties of the coating are improved.