Investigation of enamel coatings failure in desulfurization flue gas

•We found the whole process of enamel coating from corrosion to complete failure in flue gas after wet desulfurization.•The micro mechanism of enamel coating corrosion failure was obtained through various characterization methods. The enamel coating rich in alkali metal would be preferentially corroded by HCl, making the enamel coating become a porous SiO2 matrix, so that the coating gradually failed.•We compared the corrosion resistance of three enamel coatings with different compositions. The difference in the content of alkali metal, Ca, Al, Ti, Zr and other metals will affect the corrosion resistance of enamel coatings.•In order to enhance the resistance of enamel coating to desulfurization flue gas corrosion, it is necessary to reduce the content of alkali metal, ensure the uniformity of coating components and coating thickness, and eliminate sharp corners.