Improved Corrosion Resistance and Electrical Insulation Behavior of Plasma Sprayed Alumina Coatings Treated by Inorganic Sealant

In this study, alumina coatings are deposited by atmospheric plasma spraying and sealed using an aluminum phosphate solution containing a small fraction of alumina nanoparticles. Potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray tests are used to evaluate the corrosion behavior of both the as-sprayed and sealed coating samples. Besides improving corrosion resistance, the sealing treatments are also shown to increase the electrical resistance of the coatings, making them better electrical insulators.