| In recent years,with the major breakthroughs in aerospace related research,the development of aerospace technology has put forward higher technical indicators for the thermal protection system in terms of service environment,heat dissipation efficiency,structural stability,etc.,and thermal insulation coating has become a key factor restricting space development.Broadening the resistance to harsh environments and high temperature resistance of existing thermal barrier coating systems has become an urgent need to develop advanced materials for defense aviation.According to the performance requirements of the subject,this paper selects the methyl vinyl silicone rubber with simple vulcanization process as the base rubber,and vulcanizes the rapid 2,4-dichloroperoxybenzoyl peroxide as the vulcanizing agent.Due to the high temperature structural stability of the silicone rubber itself,the coating is poor.The layer completely degrades in the high temperature environment,so a variety of inorganic particles are added as a filler to ensure the high temperature insulation effect of the silicone rubber coating.By regulating the influence of the parameters analysis of each component of silicone rubber thermal insulation coating on the performance,the influence of glass powder content on the thermal properties of silicone rubber coating was discussed in depth.It was found that the glass powder can significantly improve the overall mechanical strength of the coating and ensure the mechanical strength of the coating.The coating works better at each gradient temperature.Through the research on the theory of thermal insulation,the introduction of low-density,low-conductivity hollow glass beads to block the heatinsulating flow,prolong the heat transfer path and reduce the thermal conductivity of the coating.100 phr of methyl vinyl silicone rubber,40 phr of hollow glass beads,and 30 phr of glass powder were selected as the optimum formulation.In order to investigate the performance change of the heat-insulating silicone rubber coating during high temperature,the composition of the temperature-treated samples was investigated by infrared spectroscopy(FTIR)to study the composition change of the coating,X-ray diffraction(XRD)and scanning electron microscopy(SEM).The study of coating structure changes,the results indicates that the silicone rubber coating gradually becomes ceramized with increasing temperature.The thermal degradation characteristics of the insulating silicone rubber coating are studied by thermal degradation kinetics,which is of great significance to the coating material system.The change of thermal conductivity of the coating at different temperatures was investigated and found to be only 0.109 W/(m*k)after treatment at 500 °C.In order to investigate the actual thermal insulation effect,the coating was applied to the pretreated steel plate after dissolving the coating with petroleum ether.After the step curing,a heat-insulating silicone rubber coating was prepared.The thermal shock test and high temperature experiment were carried out to investigate the bonding properties of the coating with the substrate,and it was found that the bonding was still tight at 700 °C.The static insulation performance test device was used to statically evaluate the thermal insulation performance of the coating at different thicknesses,different times and different temperatures.The heat convection stabilization time of the steel plate with 3 mm coating was increased from 80 s to 350 s,and the coating had a good actual insulation effect. |
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