Corrosion Behavior of Spark Plasma Sintering NdFeB Magnets

Polarization curve and electrochemical impedance spectroscopy(EIS)tests were applied to investigate the corrosion behaviors and corrosion kinetics of spark plasma sintering NdFeB magnets in different electrolytes.The results show that in alkaline solution the electrochemical reaction of the magnets is controlled by the step of surface charge transfer i.e.activation polarization process,the magnet with a compact passivation layer on their surface exhibits evident passive behavior in this circumstance;in weak acid solution,the electrochemical reaction of the magnets is controlled by the step of active substances adsorption process,the magnet is susceptible to corrosion in this environment since there are many active reaction channels in the anodic(Ndrich phase)areas.Compared with conventional sintered NdFeB magnet,SPS NdFeB magnet possesses excellent corrosion resistance.