Micro-laminated (ZrO2-Y2O3)/(Al2O3-Y2O3) coatings on Fe-25Cr alloy and their high temperature oxidation resistance

The micro-laminated (ZrO2-Y2O3)/(Al2O3-Y2O3) composite coatings were prepared on the surface of Fe-25Cr alloy by an electrochemical process and a sintering process alternately. FESEM analyses show that the cross section of the micro- laminated coatings has alternate six- layer films of ZrO2-Y2O3 and Al2O3-Y2O3, with the thickness of each layer in the range of nanometer or submicron. The surface of the micro- laminated coatings is composed of nanoparticles. SEM, XRD, and mass gain measurements were adopted to study the oxidation resistance of coatings on the Fe-25Cr alloy. It has been found that all the coatings are effective in protecting the substrate from oxidation, and micro- laminated coatings exhibit more excellent protectiveness performance, and the oxidation resistance is increased with increasing the layers of the micro- laminated coatings. These beneficial effects can be contributed to the mechanism, by which such a micro- laminated coating synthesizes all the beneficial effects and overcomes all the disadvantages of both the ZrO2-Y2O3 coating and the Al2O3-Y2O3 coating during the oxidation of the alloy.