SiO2 aerogel coating with organic montmorillonite compounded with flame retardants: A strategy for design of a multifunctional thermal barrier coating

To improve the thermal barrier properties of epoxy resin coatings, a composite waterborne aerogel multifunctional coating that possesses both mechanical properties and controllable barrier ability was prepared in this study. This coating incorporates granular silica aerogel, organic montmorillonite, and two flame retardants: aluminum hydroxide (ATH) and magnesium hydroxide (MH). The results showed that montmorillonite, modified with stearyl trimethyl ammonium bromide (STAB), exhibited antisymmetric and symmetric stretching vibrational infrared spectral absorption peaks of –CH3, –CH2, characteristic of the long-chain alkane quaternary ammonium salt. This indicated that the quaternary ammonium salt was intercalated into the montmorillonite interlayer, enhancing the surface lamellae. The coating effectively absorbed energy when stressed, resulting in a strength increase of 146.3%. Incorporating high porosity silica aerogel significantly improved the barrier behavior of the composite coating, enabling controlled thermal insulation and excellent corrosion resistance. The coating reduced heat transfer paths and effectively impeded heat transfer, maintaining a high corrosion inhibition efficiency (99.9%) in a 3.5% NaCl solution. Additionally, the individual actions of the two flame retardants led to highly effective flame retardant properties, with the total heat release rate (THR) reduced by about 43.5% and the total smoke production (TSP) by 40.1%.