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Corrosion Properties of NdFeB Magnets Coated by a Ni/Cu/Ni Layer in Chloride and Sulfide Environments

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Abstract

In this study, the corrosion behavior of a permanent magnetic alloy, Nd-Fe-B, coated by a triple layer of nickel-copper-nickel was studied. The corrosion resistance was investigated by (i) flux tests, carried out at 90 °C in an atmosphere containing chlorides or at 70 °C containing sulfides, (ii) electrochemical impedance spectroscopy (EIS), and (iii) potentiodynamic polarization tests, carried out in solution at different temperatures (0-90 °C) containing chlorides or sulfides. The morphology and the composition of the samples and the corrosion products were analysed by optical microscopy and scanning electron microscopy, equipped with an energy dispersive x-ray detector. The magnetic properties were characterized by magnetic flow measurements. The flux tests indicated that the triple layer of coating provided a greater corrosion resistance in atmosphere containing chlorides than the one with sulfides. The potentiodynamic and the EIS tests showed that the corrosion rate increased with temperature. The magnetic properties of the sample remained unchanged after exposure to the aggressive environment.

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References

  1. K. J. Strnat, Modern Permanent Magnets for Applications in Electro-Technology, Proc. IEEE, 78(6), 1990, p 923-946

    Article  ADS  Google Scholar 

  2. J.M.D. Coey, Permanent Magnet Applications, J. Magn. Magn. Mater., 2002, 248, p 441–456

    Article  CAS  ADS  Google Scholar 

  3. D. Brown, B.M. Ma, and Z. Chen, Developments in the Processing and Properties of NdFeB-Type Permanent Magnets, J. Magn. Mater., 2002, 248, p 432–440

    Article  CAS  ADS  Google Scholar 

  4. A.M. El-Aziz, A. Kirchner, O. Gutfleisch, A. Gebert, and L. Schultz, Investigations of the Corrosion Behaviour of Nanocrystalline Nd-Fe-B Hot Pressed Magnets, J. Alloy Comp., 2000, 311, p 299–304

    Article  CAS  Google Scholar 

  5. A.A. El-Moneim, O. Gutfleisch, A. Plotnikov, and A. Gebert, Corrosion Behaviour of Hot-Pressed and Die-Upset Nanocrystalline NdFeB-Based Magnets, J. Magn. Mater., 2002, 248, p 121–133

    Article  CAS  ADS  Google Scholar 

  6. L. Schultz, A.M. El-Aziz, G. Barkleit, and K. Mummert, Corrosion Behaviour of Nd-Fe-B Permanent Magnetic Alloys, Mater. Sci. Eng. A, 1999, A267, p 307–313

    CAS  Google Scholar 

  7. I. Costa, M.C.L. Oliveira, H.G. de Melo, and R.N. Faria, The Effects of Magnetic Field on Corrosion Behaviour of Nd-Fe-B Permanent Magnets, J. Magn. Mater., 2004, 278, p 348–358

    Article  CAS  ADS  Google Scholar 

  8. I. Gurappa, Corrosion Characteristics of Permanent Magnets in Acid Environments, J. Alloy Comp., 2003, 360, p 236–242

    Article  CAS  Google Scholar 

  9. D.F. Cygan and M.J. McNallan, Corrosion of NdFeB Permanent Magnets in Humid Environments at Temperatures up to 150°C, J. Magn. Mater., 1995, 139, p 131–138

    Article  CAS  ADS  Google Scholar 

  10. S. Sunada, K. Majima, Y. Akasofu, and Y. Kaneko, Corrosion Assessment of Nd-Fe-B Alloy with Co Addition Through Impedance Measurements, J. Alloy Comp., 2006, 408-412, p 1373–1376

    Article  CAS  Google Scholar 

  11. J. Xiao and J. Otaigbe, Polymer-Bonded Magnets III. Effect of Surface Modification and Particle Size on the Improved Oxidation and Corrosion Resistance of Magnetic Rare Earth Fillers, J. Alloy Comp., 2000, 309, p 100–106

    Article  CAS  Google Scholar 

  12. H.H. Man, H.C. Man, and L.K. Leung, Corrosion Protection of NdFeB Magnets by Surface Coatings—Part I: Salt Spray Test, J. Magn. Mater., 1996, 152, p 40–46

    Article  CAS  ADS  Google Scholar 

  13. H.H. Man, H.C. Man, and L.K. Leung, Corrosion Protection of NdFeB Magnets by Surface Coatings—Part 2: Electrochemical Behaviour in Various Solutions, J. Magn. Mater., 1996, 152, p 47–53

    Article  CAS  ADS  Google Scholar 

  14. A. Walton, J.D. Speight, A.J. Williams, and I.R. Harris, A Zinc Coating Method for Nd-Fe-B Magnets, J. Alloy Comp., 2000, 306, p 253–261

    Article  CAS  Google Scholar 

  15. S.M. Tamborim Takeuchi, D.S. Azambuja, A.M. Saliba-Silva, and I. Costa, Corrosion Protection of NdFeB Magnerts by Phosphating with Tungstate Incorporation, Surf. Coat. Tech., 2006, 200, p 6826–6831

    Article  CAS  Google Scholar 

  16. C.B. Ma, F.H. Cao, Z. Zhang, and J.Q. Zhang, Electrodeposition of Amorphous Ni-P Coatings onto Nd-Fe-B Permanent Magnet Substrates, Appl. Surf. Sci., 2006, 253, p 2251–2256

    Article  CAS  ADS  Google Scholar 

  17. L.M. Weisenberger and L. Gianelos, Metal Handbook—Surface Cleaning, Finishing and Coating, Vol 5, 9th ed., American Society for Metals, Metals Park, OH, 1987, p 161–200

    Google Scholar 

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Acknowledgments

The authors would like to acknowledge SIT La-Precisa S.p.a. for the magnetic measurements and the samples supplies.

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Authors and Affiliations

  1. DPCI, University of Padua, Via Marzolo 9, 35131, Padua, Italy

    I. Rampin, F. Bisaglia & M. Dabalà

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  1. I. Rampin
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  2. F. Bisaglia
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  3. M. Dabalà
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Correspondence to I. Rampin.

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Rampin, I., Bisaglia, F. & Dabalà, M. Corrosion Properties of NdFeB Magnets Coated by a Ni/Cu/Ni Layer in Chloride and Sulfide Environments. J. of Materi Eng and Perform 19, 970–975 (2010). https://doi.org/10.1007/s11665-009-9568-6

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  • DOI: https://doi.org/10.1007/s11665-009-9568-6

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