Corrosion resistance and mechanism of CeN, TiN and CeN/TiN bilayer composite film deposited by dual ion beam sputtering

Uranium (U) is an important engineering material in nuclear energy industry. Its environmental instability, however, posed challenges on its applications. Due to the active property and similar electronic configuration, Cerium (Ce) can be used as a reference metal to simulate the protection of uranium from corrosion. In order to improve the corrosion resistance of Ce, ceramic CeN, and ceramic TiN and CeN/TiN bilayer composite film were prepared by dual ion beam sputtering deposition system (DIBD). The crystal structure of films was identified by X-ray diffraction (XRD) and the chemical states of CeN film were characterized by the X-ray photoelectron spectroscopy (XPS). The Surface morphology and structure changes in atmospheric environment were examined by scanning electron microscopy (SEM) and XRD, The corrosion behavior was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results indicate the single film of CeN or TiN shows poor corrosion resistance, but the CeN/TiN bilayer composite film has better corrosion resistance. Based on the XPS, SEM and impedance analysis, we supposed that the loose of integrity and passivity breakdown on as deposited coating may be the corrosion inducement.