Construction and corrosion behavior of Al2O3/Al2O3-Ca2SiO4 double ceramic coating

In this study, Al2O3/Al2O3-Ca2SiO4 powders was sprayed on stainless steel substrate which contains a nickel-chromium connecting layer. At the same time, Al2O3 coatings were produced by air-plasma-spraying technology as comparison. Anti-corrosion tests in acidic corrosive atmosphere, potentiodynamic polarization measurements and thermal shock resistance tests were carried out to evaluate the protection performance of coatings. The effects of inorganic sealing agent on the microstructure and properties of the coatings were studied. The results indicated that Al2O3/Al2O3-Ca2SiO4 double ceramic coating showed a better corrosion resistance, lower corrosion rate and a better thermal shock resistance than Al2O3 coating. The sealing treatment can improve the corrosion resistance of coatings while decreasing the thermal shock resistance dramatically.