Preparation of Ni-SiC composite coatings by magnetic field-enhanced jet electrodeposition

To improve the effective working life of sintered NdFeB magnets, Ni-SiC composite coatings were prepared on NdFeB by magnetic field-enhanced jet electrodeposition. It was found that the influence of the magnetic field on the ions in the electrolyte improved the edged effect that is most likely to occur in traditional jet electrodeposition, accelerated the mass transfer of ions, and improved the coating morphology, as compared with Ni-SiC prepared by traditional jet electrodeposition. The microstructure and nanoparticle content of the coatings was characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The coating microhardness, adhesion and corrosion resistance were tested by a microhardness instrument, scratch tester and electrochemical workstation, respectively. The results show that the magnetic field enhanced jet electrodeposition caused a decrease in defects in the Ni-SiC coating surface and an increase in the flatness. When the nano-SiC particle concentration was 3  g/L, the nano-SiC content in the coating increased to 3.27%, which is higher than the 2.13% of traditional jet electrodeposition. Also, the adhesion between the coating and the NdFeB was obviously improved and there was no gap, and the corrosion resistance was also further improved.