Oxidation and hot corrosion behavior of a novel enamel-Al2O3 composite coating on K38G superalloy

A novel enamel-Al2O3 composite coating with a thin NiCoCrAlY bond coat was prepared on K38G superalloy. Results indicated that this composite coating exhibited excellent high temperature oxidation resistance at 900 and 1000 °C and hot corrosion resistance in molten sulfate salts at 900 °C, much better than solo NiCoCrAlY coating and uncoated K38G. The protection mechanism of this composite coating was different from those of traditional metallic coatings. It was no longer oxidized during tests and acted as a barrier to effectively hinder the corrosive species from migrating into substrate.