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Corrosion resistance of environment‐friendly sealing layer for Zn‐coated sintered NdFeB magnet
Author(s) -
Liu F.,
Li Q.,
Yang X. K.,
Dai Y.,
Luo F.,
Wang S. Y.,
Zhang H. X.
Publication year - 2011
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201006039
Subject(s) - corrosion , neodymium magnet , materials science , dielectric spectroscopy , microstructure , scanning electron microscope , coating , metallurgy , fourier transform infrared spectroscopy , electrochemistry , chemical engineering , composite material , magnet , chemistry , electrode , physics , quantum mechanics , engineering
In this paper, a protective sealed Zn coating (SZC) was prepared on sintered NdFeB magnet by the combination of electrodeposition and sol–gel method. The unsealed Zn coating (UZC) was also studied for a comparison. The surface morphology of UZC and the cross‐section morphology of SZC were investigated using scanning election microscope (SEM). The microstructure of Zn coating and structure of sealing layer were studied by X‐ray diffraction (XRD) and Fourier transform infrared (FT‐IR) spectrum, respectively. The corrosion characteristics of SZC and UZC in neutral 3.5 wt% NaCl solution were evaluated using electrochemical measurements including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test, indicating that the anticorrosive properties of SZC coated specimens increased 20 times compared with that of UZC coated specimens. In order to further investigate the anticorrosive properties of SZC, a long‐term immersion test was carried out in neutral 3.5 wt% NaCl solution using EIS. The results of long‐term corrosion test showed that the SZC could provide long‐term protection in neutral 3.5 wt% NaCl solution for NdFeB magnet.