Abstract
Magnetic fields parallel to electrodes were introduced during plating process to obtain ZnNi alloy films from acid baths. Effects of different magnetic intensities on the composition, nucleation magnetism, surface morphology and anticorrosion of ZnNi films were investigated. With the increase in magnetic intensity, deposition rate and nickel contents increased gradually due to magnetohydrodynamic (MHD) effects caused by Lorentz force. It was found that magnetic force Fm in the magnetic electrodeposition process could have a significant effect on the mass transfer to dramatically improve deposition rate. Maximum deposition rate (90 m h−1) was achieved when the magnetic intensity was equal to 1 T. The films were densely covered with typical nodular structure. Films of smaller grain size and smooth surface could be formed under high magnetic intensity as a result of Lorentz force and MHD effects. Moreover, ZnNi films obtained with higher magnetic intensity possessed more positive self-corrosion potential and optimal anticorrosion performance. However, much higher nickel contents in ZnNi films may drop anticorrosion performance.
Acknowledgements
This research was supported by the National Natural Science Foundation (grant no. 21171155), International Science and Technology cooperation Program of China (grant no. 2011DFA52400), Important Science and Technology innovation team of Zhejiang China (grant no. 2010R50016) and Natural Science Foundation of Zhejiang Province (grant no. LQ12E01007).