Preparation And Performance Analysis Of High Performance Silicate Based Intumescent Fireproof Coatings

With the developing of society,fire safety and the fire performance of materials are receiving increasing attention.It is an efficient and convenient measure to protect the materials or extend the effective escape time in a fire by brushing fireproof coatings.Intumescent flame-retardant coatings can achieve high fire resistance efficiency with a thinner coating layer,and its impact on the properties of the matrix material is small.So Intumescent flame-retardant coating has received widespread attention.Currently,it has been widely used in ships,buildings,and various large public facilities.Inorganic intumescent flame-retardant coating is a type of intumescent flame-retardant coating,mainly composed of intumescent silicate.Intumescent silicate loses water and crosslink when encountering flames,forming an expanded silicon layer with thermal insulation and fire prevention effects.The expanded silicon layer is dense and sturdy,with good adhesion,and can maintain good fireproof effect in the scene of a fire.The silicate coating is nonflammable,and does not produce toxic smoke during the expansion process.However,the expansion layer of the coating will melt and soften at high temperatures,resulting in a decrease in fire resistance.Therefore,further improvement to fully tap into its fire resistance potential and make up for its defects of high-temperature softening is of great significance for the use and promotion of silicate fire retardant coatings.This study is divided into the following three parts.In the first part of the study,ammonia and boric acid are used to modify the culture medium sequentially,and serve as a biological carbon source.The modified culture medium is blended with silicate coating,and obtain an organicinorganic flame-retardant coating(B-AM/SS).Ammonia and boric acid can stimulate the potential catalytic carbonization of culture medium,which can be applied in silicate coatings.Ammonia and boric acid work together to enhance the flame resistance of silicate coatings.At the same time,boric acid can also promote the cross-linking of sodium silicate,further improving the fireproof effect of the coating.The ultimate combustion test shows that the maximum fire resistance time of B-AM/SS coating can be increased to 69.7 min.The structural characterization proves that B-AM,boric acid,and silicates have a synergy in the fire prevention process,promoting the formation of char and silicate network.Observing the surface and internal morphology of the layer after the fire test,it is found that the expansion layer is denser and the pore size distribution was more uniform.In the second part of the study,we explore the rational utilization of the fluorosilicone powder,a kind of industrial waste accompanying in the phosphorus chemical industry.A modified sodium silicate(FSS)flameretardant coating is synthesized by fluorosilicic powder it with silica and sodium hydroxide directly.The fluorosilica powder under alkaline conditions can generate sodium fluorosilicate with cross-linking and curing effects,promote the formation of silicate cross-linked network structure,and improve fire prevention effect.The ultimate combustion test shows that the fire resistance time of FSS can reach up to 67.4 min,and X-ray diffraction(XRD)testing proves that the expansion layer structure is more regular and less prone to cracking during the fire resistance process.The results of thermogravimetric analysis(TGA)shows that fluorosilicone powder as a raw material can improve the thermal stability of the coating.Microscopic observation reveals that the modified expansion layer has a denser structure and more uniform pore size distribution,and a silica nanowire structure is generated to prop up the expansion layer.In the third part of the study,expanded vermiculite is added as an inorganic filler to the silicate flame-retardant coating,obtaining an expanded vermiculite modified silicate flame-retardant coating(EVM/SS).The reinforce and support effect of the layered structure of expanded vermiculite is utilized to compensate for defect of the high-temperature softening of the coating.In the hightemperature and high-power combustion test,the fire resistance time of EVM/SS can still reach 54.3 min,and the expansion layer remains unbroken after 20 min of flame impact from the spray gun.XRD testing has proven that expanded vermiculite partially transforms into cordierite at high temperatures,improving the thermal stability of the expanded silicon layer.The SEM images demonstrate the reinforcing effect of expanded vermiculite on the pores.