Study On Preparation Of Low Melting Phosphate Glass And Its Application In Inorganic Thin Fire Retardant Coating For Steel Structure

At present, water-thin intumescent fire-retardant coating for steel structure are widely used, the choice of polyphosphate as a dehydrating agent, melamine as a blowing agent and pentaerythritol as a carbon agent, which is the most classic and efficient intumescent flame retardant system.The emphasis of the research of domestic and foreign researchers is how to further improve the existing organic expansion system, improve performance or eliminate the part defects, but not fundamentally change the release of large amounts of toxic smoke and other defects of organic intumescent fire-retardant layer, which is too soft and easy to be damaged in the high temperature.This study select the new ideas, starting from the inorganic material of non-toxic and inexpensive, developed a new type of inorganic ultrathin intumescent fire retardant coating for steel structure. It is creatively to make the green low melting glass powder applied in the coating. In the fire, the melt foaming principle of producing foamed ceramic is used to form a high efficiency and stability intumescent layer.First of all, the Ba O-B2O3-P2O5 system low melting glass powder is developed, the melting temperature of the best low melting glass powder formula is about 550 ℃, the products of this formula meet the requirements of new type fire retardant coating intumescent system on melt material.After the research, two kinds of new inorganic intumescent system formulas of fire-retardant coating are developed. One of them, with the emulsion as binder, with magnesium hydroxide, low melting glass powder and other inorganic materials for flame retardant system materials, is an inorganic intumescent fire retardant coating based on emulsion; another formula with high modulus sodium silicate as binder, low melting point glass powder as high temperature melt foaming material, expanded graphite and magnesium hydroxide as foaming agent, prepared a dense, stable and high strength expanded layer. TG,DTG, SEM, the flame test, gas analysis experiment and other analysis means are adopted on the fire retardant coating performance and flame retardant mechanism were studied, then compared these performance with the P-C-N organic expansion system coating.The research results show that, the obtained formula groups in this research in various temperature ranges can be efficient matching, with synergistic effect. Among them, emulsion based thin intumescent fire retardant coating for steel structure and P-C-N organic expansion system coating have the similar flame retardant performance, after the flame test for two hours, the back surface temperature of steel are stable at around 210 ℃, but the emulsionbased inorganic thin intumescent fire retardant coatings relative organic expansion system coating of toxic smoke decreased by 93.7%, the expanding layer intensity increased more than60%, the inorganic residues of the expanding layer which is very important to the flame retardant effect increased by 102.6%.The new inorganic super thin fire retardant coatings formulation relative to P-C-N organic expansion system formulation performance a breakthrough promotion, after 2 hours of fire retardant coating experiment, the back temperature of steel with new formula of coatings stable at 150℃, significantly lower than 210℃ in the organic formula, more stable and long flame retardant effect. Toxic smoke quantity relative emulsion based inorganic thin intumescent fire retardant coatings further reduced about 34.6%, witch relative organic system formula to reduce the amount of toxic smoke more than 95.9%. The intensity of the expansion layer relative organic system of carbon foam layer is improved more than 350 times, the inorganic residues of the final expansion layer relative organic system formula coating increased 156.8%, after XRD test and analysis, the new inorganic formulation coating generated Mg Si O3·Mg O ceramic materials in the flame retardant process.The new type of inorganic super thin fire retardant coating for steel structure have been developed in this paper, which comprehensive performance is very excellent. The formed dense, high stability inorganic flame retardant expanding layer is composite with obturator structure Mg Si O3·Mg O ceramics and low melting glass powders. A new inorganic expansion system with highly efficient and non-toxic characteristics will be an important development direction of the future of fire retardant coating.