Corrosion mechanism of Ni deposits on magnets by pulse current electro-deposition

Abstract Ni was deposited on sintered NdFeB magnets by pulse current (PC) electro-deposition. And a better corrosion resistance of the deposits was observed. Growth direction of the Ni particles was changed to be in two dimensions, which provided the minimal defects and smooth interface, the smooth and pyknotic Ni deposits were observed. The texture of the Ni deposits by PC showed a preferred orientation along the (111) plane and a reduction in the number of extra phases, which improved the quality and corrosion resistance of the Ni deposits. In addition, the difference of the diffusion energy barrier on the different crystal surfaces results in electrochemical corrosion of the Ni deposits by first-principles calculation. These results can provide an appropriate explanation for the corrosion mechanism of Ni deposits, the theoretical corrosion model of Ni deposits was established.