A thermal expansion-matched corrosion-resistant ceramic coating on low-carbon steel

Low-carbon steel, widely used for industrial liquid storage and processing vessels, requires protective coatings to endure corrosive conditions. A key challenge for ceramic-coated steel is thermal mismatch. Here, a ceramic coating was prepared on low-carbon steel using three glass powders and one enamel powder. The coating is amorphous, with a microhardness of 620 ± 11 HV and adhesion strength of 6.15 MPa. The coating's coefficient of thermal expansion closely matched that of the substrate over 25 °C to 500 °C, with only a slight deviation of 2 × 10 −6 °C −1 . After 15 thermal cycles, the coating showed <0.1% mass change and no cracking. In neutral salt spray testing, only slight edge rusting occurred after 240 h. Electrochemical impedance spectroscopy tests in acidic, neutral and alkaline electrolytes revealed a nearly ideal capacitive phase angle of 65° to 85°. The corrosion current densities of the coated samples in acidic ((2.492 ± 0.101) × 10 −7 A/cm 2 ), neutral ((6.199 ± 0.373) × 10 −8 A/cm 2 ) and alkaline ((5.584 ± 0.559) × 10 −8 A/cm 2 ) environments were reduced by 3.3 to 3.7 orders of magnitude compared to the bare steel. This highly compatible and durable ceramic coating is a promising candidate material for the protection of industrial liquid processing and storage equipment.