Study on preparation and fire-resistant property of an organic silicone coating with compounding glass powder

To improve the fire resistance performance of silicone resin, a silicone coating which can resist a flame temperature at 1200°C was designed and prepared by compounding glass powder, Mg(OH)₂, talcum powder, kaoline, Al₂O₃, TiO₂, and SiO₂ as functional fillers. After burning and oxidizing by acetylene flame at 1200°C for 90 min, there is no penetration and peeling of silicone coating. Moreover, the highest temperature on the back of the substrate is 263°C and the average temperature of it is 207°C, which are both lower than the softening temperature of steel. As analyzed, the functional fillers in silicone coating are evenly distributed. There are still high-temperature-resistant fillers including talcum powder, kaoline, SiO₂, TiO₂, and Al₂O₃ in the char layer formed by the fire-resistant coating. After fire resistance test, the char layer of silicone coating does not possess a large area of voids, which indicates that the composite glass powder may melt and flow in time in the range of 400–500°C. The glass powder with low-melting point supplements the vacancies caused by pyrolysis of organic silicone resin film former. Furthermore, the existence of glass powder and Mg(OH)₂ composite improves the high-temperature adhesion of silicone coating, while talcum powder, kaoline, SiO₂, TiO₂, and Al₂O₃ in the silicone coating have the function of reinforcement. The high-temperature resistance of talcum powder, kaoline, SiO₂, TiO₂, and Al₂O₃ improves the fire resistance of the silicone coating as well.