High temperature oxidation of NiCrAlY, nanocrystalline and enamel-metal nano-composite coatings under thermal shock

Thermal shock behavior of the NiCrAlY coating, the nanocrystalline coating with the same composition of the alloy substrate, and the enamel-metal nano-composite coating is investigated. All the three coatings perform well under thermal shock in air. When thermal shock is conducted in water, cracks nucleate at surface, grow in oxide scale and some of them penetrate into the underlying NiCrAlY or nanocrystalline coatings. For the enamel composite coating, its mass gain after thermal shock is the lowest among the three coatings with no cracks developing at surface. It performs better than the two metallic coatings do in thermal shock conditions.