Influence of nano-boron nitride on fire protection of waterborne fire-resistive coatings

Nano-sized BN and micron-sized BN were used as fillers in fire-resistive coatings. The experimental results suggested that nano-BN with a multilayer structure could remarkably enhance the fire protection of fire-resistive coatings. Turbiscan data indicated that nano-sized BN had better dispersion stability in waterborne coatings than micron-sized BN. TGA results showed that nano-sized BN could enhance the thermal stability of the coatings, especially under high temperature. FTIR and EDS results exhibited that nano-sized BN was helpful in reducing the oxidation degree and enhancing the antioxidation property of the char layer under high temperature. The morphology observation demonstrated that nano-sized BN could improve the foam structure of the char layer so as to improve the mechanical strength of the char layer. Nano-sized BN was helpful for the even distribution of the cells; thus the efficiency of heat insulation of the char layer was enhanced. These results proved that nano-sized BN was beneficial to the forming and expanding of the intumescent char layer, and could provide better fire protection for the coatings.