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Low temperature Al2O3 sol-gel coatings on neodymium iron boron sintered magnets: Study of adhesion and corrosion performance

  • Original Paper: Sol-gel and hybrid materials for dielectric, electronic, magnetic and ferroelectric applications
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Abstract

Sol-gel alumina coatings have been deposited on neodymium-iron-boron magnets for corrosion protection. The coatings present a compact amorphous structure due to the low thermal treatment (500 °C) with a thickness ranging from 0.8 to 2 microns, a Vickers hardness of 10 GPa and good adhesion to the substrate, measured by scratch test, with a failure mode of tensile cracking and chipping. The coatings are effective in protecting the NdFeB magnets from corrosion with reduction of current density (i.e. 2.07 × 10−6 A/cm2 for 2dip sample) of one order of magnitude with respect to the neat sample (1.15 × 10−5 A/cm2).

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Acknowledgements

We wish to thank Sisram s.p.a and Mr. Luigi Sonessa for providing the NdFeB magnets.

Author contributions

All authors contributed to the study conception and design. MB and FN were involved in planning and supervised the work. Material preparation, data collection and analysis were performed by MB, LP, LF and VS. The first draft of the manuscript was written by MB and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Authors and Affiliations

  1. Department of Enterprise Engineering “Mario Lucertini”, and INSTM RU Roma-Tor Vergata, University of Rome “Tor Vergata”, Via del Politecnico 1, 00133, Rome, Italy

    Mario Bragaglia, Lorenzo Paleari & Francesca Nanni

  2. Department of Chemistry Science and Technologies and NAST Centre, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133, Rome, Italy

    Laura Fazi

  3. Department of Physics and NAST Centre, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133, Rome, Italy

    Valerio Scacco

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  1. Mario Bragaglia
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Correspondence to Mario Bragaglia.

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Bragaglia, M., Paleari, L., Fazi, L. et al. Low temperature Al2O3 sol-gel coatings on neodymium iron boron sintered magnets: Study of adhesion and corrosion performance. J Sol-Gel Sci Technol 106, 95–106 (2023). https://doi.org/10.1007/s10971-022-06007-4

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