Silicon dioxide composite heat insulating coating and preparation method thereof

The invention relates to a silicon dioxide composite heat insulating coating and a preparation method thereof. The silicon dioxide composite heat insulating coating comprises a subcoat and a closing layer from bottom to top. The subcoat is prepared from, by weight, 20-25 parts of coarse floating bead particles or coarse sinking bead particles, 80-100 parts of polymer mortar and 5-10 parts of water, and the closing layer is prepared from, by weight, 70-80 parts of fine floating bead particles or fine sinking bead fine particles, 3-8 parts of silicon carbide, 15-25 parts of polymer mortar and 5-6 parts of water. The preparation method is simple, floating beads and sinking beads are adopted as raw materials to prepare the silicon dioxide composite heat insulating coating, the heat resistance of silicon dioxide and silicon carbide is fully utilized, the stability of heat expansion and cold contraction of the polymer mortar is used in cooperation, therefore, the prepared coating cannot crack or fall off whether in spring or summer or autumn or winter under sunlight irradiation, the floating beads and the sinking beads are developed and utilized, energy is saved, and economic benefits 10-20 times those of the raw materials and energy-saving social benefits can be achieved.