Self-healing metal-enamel composite coating and its protection for TiAl alloy against oxidation under thermal shock in NaCl solution

Isothermal oxidation and thermal shock behavior of enamel coatings added with or without nano-nickel particles on TiAl alloy at 800 degrees C were investigated. Both the two enamel coatings provide high oxidation resistance for the alloy substrate, and the metallic particles impose little impact. Under thermal shock, however the pure enamel coating suffers serious cracking and spallation. For the metal-enamel composite coating, its thermal shock resistance is largely improved. Once cracking, the nano-nickel particles are oxidized in hot air and expanded in volume, which combines with the high-temperature viscoelasticity of enamel to make the crack heal completely and avoid spallation.