Thermal insulating epoxy composite coatings containing sepiolite/hollow glass microspheres as binary fillers: morphology, simulation and application

Abstract Sepiolite and hollow glass microspheres (HGMs) are used as binary fillers to prepare thermal insulating composites to improve the protecting durability of epoxy composites on Mg alloy. Sepiolite can be evenly dispersed inside epoxy at around 10% (vol.%), while HGMs are also found evenly distributed in this matrix with content up to 45% (vol.%), as shown in the scanning electron microscope pictures. Their thermal stability and thermal insulation ability improve simultaneously with the increase of the inorganic filler, as shown in the thermal gravimetric analysis results and thermal insulting tests. According to the three-dimensional finite element analysis using ANSYS software (ANSYS Inc., USA), their thermal conductivity coefficients are found to decrease linearly with the increase in HGMs volume fractions. The tested temperature changes on the opposite side of the Mg alloy coated with sepiolite/HGMs/epoxy composites match well with those on the stimulant curves, indicating the reliability of the models and the thermal insulating functions provided by the fillers.