摘要
Al coated NdFeB magnets were prepared by plasma-assisted-physical-vapor-deposition(PA-PVD)method fo r enhancing the corro sion resistance.Mo rphologies and structures were characterized by an Xray diffractometer and a scanning electron microscope.Corrosion behaviors of the samples with different bias voltages were studied by electrochemical methods and neutral salt spray test,respectively.The bias voltage during the deposition process was optimized according to the coating structures and corrosion resistances.The density and flatness of Al coating increase with increasing the bias voltage,and at the same time the thickness decreases.The coating density and thickness turn to be stable when bias voltage is 1800 V.Also,the corrosion behaviors of PA-PVD Al coatings in different media,such as NaOH,HNO_(3) and NaCl solutions,were studied.The self-corrosion potentials(E_(corr)) of PA-PVD Al coatings almost keep constant in NaOH and HNO_(3) solutions with diffe rent concentrations.However,the self-corrosion current densities(J_(corr)) decrease with the increasing concentrations.E_(corr) shifts to negative potential and J_(corr)decreases gradually when increasing the concentration of NaCl solution.The corrosion mechanisms of Al coatings are discussed based on the corrosion behaviors in different media.
基金
Project supported by Fundamental Research Funds for the Central Universities(JZ2019YYPY0291)。
