Enhanced Corrosion Resistance of Zn‐Coated NdFeB Magnets in a Chloride Environment

ABSTRACT In this study, the corrosion behavior of NdFeB magnets coated with Zn from an acidic chloride bath was comprehensively analyzed at tuned coating thicknesses of 5, 8, and 15 µm. The surface morphology, elemental composition, and phase structure of the coatings were examined using scanning electron microscopy, energy‐dispersive x‐ray spectroscopy, and x‐ray diffraction. The results revealed dense morphology, high crystallinity, and strong adherence of Zn to the NdFeB surface across all thicknesses. Electrochemical analyses, including potentiodynamic polarization and electrochemical impedance spectroscopy, were conducted to assess corrosion behavior. In particular, the 15 µm thick Zn coated NdFeB exhibited a tenfold reduction in corrosion current density (0.369 × 10 − 6 A/cm 2 ) and a tenfold increase in polarization resistance (5857 Ω.cm 2 ), compared to bare NdFeB (7.94 × 10 − 6 A/cm 2 ; 548 Ω.cm 2 ) while retaining over 95% of magnetic performance. A comprehensive analysis of corrosion‐induced degradation was conducted to further elucidate the role of protective Zn (OH) 2 /ZnO barrier layer in the enhanced corrosion resistance of thicker coatings.