BN-TiO2 multilayer coating on AZ91 for enhanced corrosion performance in marine environments

Magnesium alloys have recently been used in marine applications due to an attractive combination of low density and high strength/weight/ratio. However, the corrosion resistance of magnesium alloys should be improved for practical applications. In this study, BN-TiO2 multilayer films were deposited with different numbers of bilayers (2 and 4) on AZ91 magnesium alloys to enhance the corrosion resistance of magnesium alloys in marine environments. The microstructure and wettability properties of uncoated and multilayer film-coated alloys were comparatively investigated via XRD, SEM, AFM, and contact angle measurement systems. The corrosion performance of uncoated and coated samples has also been evaluated using electrochemical polarization and impedance measurements in artificial seawater. The corrosion performance values of multilayer film-coated alloys were better than the uncoated alloy values. Corrosion resistance and hydrophobicity of coated samples also increased with the number of bilayers owing to the smaller grain size, increased layered interfaces, and high structural density.