Self-repairing non-expanded flame-retardant coatings prepared by sol-gel method

The frequent occurrence of building fires has triggered a compelling need for flame-retardant coatings. However, the existing flame-retardant coating technologies are high-cost, inefficient, and environmentally unfriendly. In this work, a silica-alumina sol has been developed as the substrate of the flame-retardant coatings. Boron nitride (h-BN) and glass powders with low melting temperature are employed as fillers to improve the flame retardancy. This kind of hybrid coatings can form a high-viscosity liquid-solid phase and be re-paired in high-temperature environments. The experimental results indicate that the as-prepared hybrid coating can act as an oxygen barrier to protect the substrates against fire. Besides, a carbonous layer has been formed on the coating surfaces when exposed to flames, which can stem the spread of the flame spread. Due to the low cost, high stability, self-repairing and easy preparation, the self-repairing hybrid coatings show great potential for application in the fields of fire-proof and flame retarding.