Enhanced Corrosion Resistance of CuAl/BN Coatings through the Addition of Rare Earth Elements and High-Temperature Oxidation Treatment

Abradable seal coatings represent a critical technology within the realm of advanced power systems, designed to minimize airflow channel leakage, thereby reducing energy consumption and enhancing overall efficiency. In the present study, CuAl/BN, CuAlLaF3/BN, and CuAlY/BN abradable seal coatings were prepared using plasma spraying technology. Both the as-deposited coatings and high-temperature oxidation-treated coatings were comprehensively investigated by means of scanning electron microscopy (SEM), open-circuit potentials (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), salt-spray corrosion testing, and bond strength evaluations. The results show that the addition of rare earth elements to the CuAl/BN coatings does not enhance the corrosion resistance of the coatings and even leads to a decrease in the corrosion resistance of the coatings. In contrast, the CuAlY/BN coatings exhibited a significant improvement in corrosion resistance following an oxidation treatment at 550 °C. This enhancement is attributed to the yttrium (Y) element, which facilitates the formation of passivation films and confers a resistance effect, thereby bolstering the coatings’ resistance to corrosion. The bond strength of the high-temperature oxidation-treated CuAlY/BN coating was improved by about 30% after 960 h of salt-spray corrosion.