HEAT-RESISTANT COATING COMPOSITION

PURPOSE:To obtain a coating composition which, when applied to the surface of a metal, can form a coating film excellent in heat resistance, oxidation resistance and adhesion by adding an aqueous polyphenylene sulfide dispersion to an inorganic composition based on colloidal silica and a silicate. CONSTITUTION:The title heat-resistant coating composition is obtained by adding 1-10pts.wt. (in terms of the solid matter) aqueous polyphenylene sulfide dispersion to 100pts.wt. (in terms f the solid matter) inorganic composition comprising 20-45wt.% colloidal silica, 20-45wt.% potassium silicate, 5-15wt.% sodium silicate, 1-3wt.% hydrated aluminum silicate and 5-30wt.% oxide or hydroxide of a Group II-IV metal [e.g., MgO, Ca(OH)2, Al2O3 or ZrO2]. This coating composition can give a film which can exhibit heat resistance and corrosion resistance in a high temperature region (650 deg.C) when it is treated at a low temperature (200 deg.C) for a short time, can be applied to a substrate subjected to only a simple surface treatment, and is particularly suitable as a rust-preventive coating for an automobile engine or its peripheries.