Protection of Nd2Fe14B-based melt-spun ribbons using nanoscale sol–gel derived films of SiO2 and Al2O3

We have coated NdFeB melt-spun powders used for the production of bonded magnets with SiO2 and Al2O3 using the sol–gel technique. Highly accelerated stress tests were conducted to compare the corrosion properties of the powders by measuring the weight change. The composition and microstructure of th...

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Bibliographic Details
Published in:Surface & coatings technology 2013-10, Vol.232, p.123-130
Main Authors: Sojer, D., Skulj, I., Kobe, S., Kovač, J., McGuiness, P.J.
Format: Article
Language:English
Subjects:
Aluminum oxide
Applied sciences
Bonded magnets
Coating
Coatings
Corrosion
Corrosion environments
Corrosion prevention
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Magnetic properties
Materials science
Melt spinning
Metals. Metallurgy
Physics
Production techniques
Rare-earth magnets
Silicon dioxide
Sol gel process
Sol–gel
Spectroscopy
Surface treatment
Surface treatments
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Summary:We have coated NdFeB melt-spun powders used for the production of bonded magnets with SiO2 and Al2O3 using the sol–gel technique. Highly accelerated stress tests were conducted to compare the corrosion properties of the powders by measuring the weight change. The composition and microstructure of the powders and surface layers were determined using Auger-electron spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, secondary-electron spectroscopy and electron-diffraction spectroscopy. The magnetic properties were compared using a vibrating-sample magnetometer. Both the SiO2 and Al2O3 coatings resulted in a superior corrosion resistance and better magnetic properties. •NdFeB melt-spun powders have been coated by the SiO2 and Al2O3 via sol–gel route.•After the HAST the coated powders were unaffected by corrosion.•Magnetic properties of the coated powders remained unaffected by HAST.•This expands the use of NdFeB melt-spun powders to 110°C and 90% humidity.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2013.04.062