Influence Of Low-melting Glass And Design Of Double-layer Structure On Performance Of Inorganic Ultra-thin Steel Structure Fire-Retardant Coatings

This paper addresses the issues of organic ultra-thin fire-retardant coatings for steel structures that emit toxic fumes during fires and poor heat-resisting performance of fire-resistant structures.The inorganic ultra-thin steel fire-retardant coatings prepared by our research team can effectively solve these problems,but During the experimental fire test,the coating appeared hollow and melt-through,which greatly affected the fire performance of the coating.In order to ensure the stable and excellent fireproof performance of the inorganic ultra-thin steel structure fire-retardant coating during the fire,we used low-melting glass and The double-layer structure is designed to optimize the intumescent structure and high temperature resistance of the inorganic fireproof system,and to solve the hollow and melt-through problems of the paint in the fire.Using the fire temperature-time curve,TG,flue gas analysis,and bondability analysis methods,the low-melting glass most suitable for the inorganic fireproof system was determined,and the inner and outer coating formulations and the painting ratio of the double-layer coating were obtained.Preparation of inorganic fire-retardant system with excellent fireproof performance,high heat insulation efficiency and low smoke emission.The main research work is as follows:?1?The influence of the basic composition of the inorganic swelling system on the properties of the paint,film formation,fire prevention,and the like was investigated.The experimental results show that the addition of 3.0-mode liquid sodium silicate 45%,magnesium hydroxide 25%,alumina 20%,low-melting glass 6%,latex powder 4%,the coating at room temperature coating surface is smooth and flat The steel plate substrate is tightly bonded and has excellent fire resistance.?2?The influence of the composition,melting range and dosage of the low-melting glass on the fire performance of the inorganic ultra-thin intumescent steel structure fire-retardant coatings was studied.Fire test results show that the addition of 6%Bi₂O₃-B₂O₃-ZnO?325-390-435°C?can effectively improve the expansion structure and thermal insulation properties of the coating.The expansion ratio of the fire protection coating is about 13 times and can be guaranteed.More than 2h stable fire resistance.Thermogravimetric analysis tests show that the coating can still retain 77.34%residue at high temperatures,ensuring thermal stability of the coating at high temperatures.?3?The influence of the double-layer structure design on the fire performance of the inorganic ultra-thin intumescent steel structure fire-retardant coatings was studied.The internal and external coating formulations and the thickness of the internal and external coating layers during construction were optimized.The experimental results show that:The optimized inner coating formula is:3.0 mode liquid sodium silicate,59.8%,aluminum hydroxide,36.3%,latex powder,3.9%;the optimized outer coating formula is:3.0 mode liquid sodium silicate 43.2%,aluminum hydroxide 32.4%,magnesium oxide 14.4%,low-melting glass 5%,latex powder 5%.Excellent fire performance was exhibited,and the thermal expansion rate reached 10.24.The inner thermal insulation structure is dense,the hole structure is evenly distributed,and the fire resistance of the outer layer is stable.When the thickness of the inner and outer layers is 1:2 to 1:1:1,the inner coating can be expanded by a relatively large number to form a uniform expansion structure,and is fully bonded with the steel structure,and exhibits excellent fire resistance and heat insulation effect.Improve the fire-retardant properties of fire-retardant coatings.The final optimized fire-retardant paint passed the fire test,and the final temperature was maintained at about 240°C,which was far below the fire-resistant limit temperature of the steel structure.?4?Comparing the fire performance of the two-layer inorganic fire retardant coating obtained after o ptimization with the commonly used organic fire retardant coatings and predecessors'single-layer inorganic fire retardant coatings,through fire test,expansion structure,smoke emission,and fire retardant residue And other analysis.The experimental structure shows that the optimized two-layer inorganic fireproof coating can form a porous expanded structure in the fireproof test process,its expansion ratio reaches about11 times,and the final fireproof temperature is maintained at about 230°C.It is the fireproof temperature in three kinds of coatings.The lowest one,at the same time,the double-layer coating significantly reduces the release of flue gas,which is reduced by about 78%compared with the organic coating.The final quality of the coating residue is maintained at more than 75%,and the steel structure is effectively protected.