Protective coating for high-temperature heat treatment of carbon steel and preparation method of protective coating

The invention discloses carbon steel high-temperature heat treatment protective paint and a preparation method thereof and belongs to the field of high-temperature processing protection. The protective coating for high-temperature heat treatment of the carbon steel comprises the following components in percentage by mass: 50%-55% of MgO-SiO2 amorphous ceramic powder, 4%-6% of alumina powder, 1%-1.5% of zinc oxide powder, 1%-1.5% of chromium sesquioxide powder, 6%-7% of sodium silicate powder, 1%-1.5% of hydroxyethyl cellulose, 1.5%-2% of polyethylene glycol 4000 and the balance of water. MgCl2. 6H2O and Na2SiO3. 9H2O are used as precursors of the MgO-SiO2 amorphous ceramic powder, and the MgO-SiO2 amorphous ceramic powder is prepared by a sol-gel method. The product has high homogeneity, the MgO-SiO2 amorphous ceramic powder is high in activity, crystallization transformation occurs at the high temperature, in-situ sintering is performed to form a compact and stable forsterite phase, in-situ generation of an