To address high-temperature corrosion at heating surface of coal-fired boilers
a composite ceramic coating on surface of 20G steel sheet was prepared by slurry method. After sintering
the composite ceramic coating had a relatively dense surface and good bonding to the substrate. Both uncoated and ceramic-coated steel sheets were studied for high-temperature corrosion resistance in sulfur dioxide (SO2) by thermal kinetic analysis method. The results show that corrosion of the coated and uncoated steel sheets adheres to one dimensional diffusion reaction kinetic model at 400-500℃. Although activation energy of coated steel corrosion was lower than the uncoated one
the coating provided preferable high-temperature corrosion resistance. After exposure to SO2
the appearance
element contents and phase structure of the sheets were characterized. Potassium sulfate (K2SO4) crystal grains were found to form on the coating surface. However
K2SO4 was not detected inside coating because relatively dense coating blocked sulfur diffusion.