Abstract: The inorganic lightweight foam materials with excellent thermal insulation were prepared using sodium silicate as main raw materials.The heating temperature was determined by TG-DSC.The microporous structure of foaming material was characterized by scanning electron microscope.The influence of fly ash，aluminum chloride，and silicone on the properties of the material was studied.Compressive strength was improved by the addition of the fly ash and aluminum chloride.The hydro- phobicity was enhanced by adding silicone.The lightweight sodium silicate foam insulator with additive of 12%（mass fraction， same below） fly ash，4.5% aluminum chloride，and 0.8% silicone was prepared by controlling the heating temperature at 250 ℃. The prepared inorganic lightweight foam materials showed enhanced compressive strength of 0.81 MPa，better hydrophobicity with contact angle of 159°，and lower shrinkage percentage of 1.91% at 100 ℃ for 10 h.

Key words: sodium silicate, insulation material, compressive strength, hydrophobicity