A MgO–SiO2–Al2O3–ZnO ceramic-glass coating to improve the anti-oxidation of carbon steel at high temperature

Abstract

In this paper, a MgO–SiO2–Al2O3–ZnO ceramic-glass coating sprayed on carbon steel was studied at high temperature. The property of the MgO–SiO2–Al2O3–ZnO ceramic-glass coating was analyzed in a range of 900°C and 1 150°C a share. The experimental results indicated that the MgO–SiO2–Al2O3–ZnO coating exhibited powerful anti-oxidation property for carbon steel. The MgO–SiO2–Al2O3–ZnO coating could improve the anti-oxidation performance of carbon steel by 84% at 1 050°C for 60 min. The Ea of blank and coated samples were 108.65 and 202.55 kJ/mol, respectively. The kp of the blank sample (0.61 mg2·cm-4·s-1) was 7.6 times as much as that of coated sample (0.08 mg2·cm-4· s-1). It demonstrated the coating slowed down oxidation reaction rate and then improved the anti-oxidation performance of carbon steel. The possible protection mechanisms of the MgO–SiO2–Al2O3–ZnO ceramic-glass coating were also investigated using the SEM-EDS, XRD and TG-DTA characterization methods. The mixture formed between the coating and steel substrate (such as MgFe2O4, ZnFe2O4, MgSiO3, FeSiO4, ZnSiO4, SiO2, Al2O3, and (FexMg1-x)2SiO4 (x=0.4, 0.85, 0.94)) played a role in blocking the spread of ions and improved the oxidation resistance of carbon steel during heating treatment. The synergy of the formed Al, Mg and Zn compound layers in the coating could also block spread of oxygen and iron ions and exert an influence on enhancing anti-oxidation property.