High-temperature thermal treatment of co-deposition of Zn-10ZnO-25Ant hill particulate composite coating on mild steel

Zinc coating is usually restricted to the operating temperature of not more than 250 °C. In order to increase the operating temperature of zinc coating that motivates the presence study, a composite coating of Zn-10ZnO-25Ant hill on mild steel surface was produced by a co-deposition route. Thermal treatment was done at temperature of 500, 700 and 900 °C. The microstructure, hardness values, corrosion and wear test were determined. The presence of hard phases of ZnSiO₃, Al₂O₃·SiO₃ and SiO₂ were obtained in the coated sample. Fine, uniform distributed structure of coated sample was obtained at 700 °C. The increases in the hardness values of the coated samples were attributed to the hard phases of ZnSiO₃, Al₂O₃·SiO₃ and SiO₂ formed. Zn-10ZnO-25Ant hill + 700 °C have the higher potential and lower corrosion rate of all the samples. Corrosion rates of 4.268 and 0.933 mpy were obtained for the uncoated mild steel and coated mild steel at 700 °C. The work has established that thermal stability of Zn-10ZnO-25Ant hill + 700 °C was in improving the properties of the developed coating.