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<p>Hexagonal boron nitride (hBN) nanosheets were functionalized with polydopamine (PDA) to form PDA-modified hBN (PhBN) hybrids, enhancing their dispersibility in aqueous systems. PhBN-reinforced epoxy resin composite coatings were then deposited onto sintered NdFeB magnets via cathodic electrophoresis to improve corrosion resistance. The morphology and microstructure of the coatings were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Corrosion behavior was analyzed using dynamic potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and static full immersion tests. Compared to pristine hBN, PhBN filler significantly enhanced the corrosion resistance of the epoxy coating. The optimized EP/PhBN(0.5) coating maintained an impedance modulus (|Z|₀.₀₁ Hz) of 4.22 × 10⁶ Ω·cm² after 40 days of immersion in 3.5 wt% NaCl solution, two orders of magnitude higher than the EP/hBN(0.5) coating. Concurrently, the corrosion potential (<i>E</i><sub>corr</sub>) exhibited a positive shift by 379 mV (from − 0.805&#xa0;V to -0.426&#xa0;V), and the corrosion current density (<i>j</i><sub>corr</sub>) decreased from 1.15 × 10⁻⁶ A·cm⁻² to 1.12 × 10⁻⁸ A·cm⁻². This superior corrosion resistance is attributed to the PDA modification improving the aqueous dispersion of hBN nanosheets, thereby enhancing their ability to fill internal pores within the epoxy coating and strengthen its passive barrier effect.</p>

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Fabrication and corrosion resistance of PhBN-reinforced epoxy composite coatings on sintered NdFeB magnets

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Haihong Zhang,
  • Xiunan Li,
  • Pengjie Zhang,
  • Dongmei Wang,
  • Jiajia Si,
  • Minna Guo,
  • Wangqiang Shen,
  • Guangqing Xu,
  • Jun Lv

摘要

Hexagonal boron nitride (hBN) nanosheets were functionalized with polydopamine (PDA) to form PDA-modified hBN (PhBN) hybrids, enhancing their dispersibility in aqueous systems. PhBN-reinforced epoxy resin composite coatings were then deposited onto sintered NdFeB magnets via cathodic electrophoresis to improve corrosion resistance. The morphology and microstructure of the coatings were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Corrosion behavior was analyzed using dynamic potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and static full immersion tests. Compared to pristine hBN, PhBN filler significantly enhanced the corrosion resistance of the epoxy coating. The optimized EP/PhBN(0.5) coating maintained an impedance modulus (|Z|₀.₀₁ Hz) of 4.22 × 10⁶ Ω·cm² after 40 days of immersion in 3.5 wt% NaCl solution, two orders of magnitude higher than the EP/hBN(0.5) coating. Concurrently, the corrosion potential (Ecorr) exhibited a positive shift by 379 mV (from − 0.805 V to -0.426 V), and the corrosion current density (jcorr) decreased from 1.15 × 10⁻⁶ A·cm⁻² to 1.12 × 10⁻⁸ A·cm⁻². This superior corrosion resistance is attributed to the PDA modification improving the aqueous dispersion of hBN nanosheets, thereby enhancing their ability to fill internal pores within the epoxy coating and strengthen its passive barrier effect.