Abstract
The work aims to develop a new environment-friendly copper plating technology on the surface of NdFeB. The CuCl-EMIC ionic liquid was used to pretreat the NdFeB matrix by anodic activation, and the copper layer was prepared on NdFeB surface by electrodeposition. Cyclic voltammetry curves of the CuCl-EMIC ionic liquid and potentiodynamic polarization curves of copper coating samples were measured by electrochemical workstation. The morphology, composition and phase structure of the NdFeB matrix and copper coatings were investigated by scanning electron microscopy, energy dispersive spectrometry and X-ray powder diffraction. The surface roughness of the NdFeB matrix and the bonding force of copper coatings were detected by the roughness meter and the drawing tester. CuCl-EMIC could be melted at room temperature when the molar ratio was 2:3~3:2, and crystalline copper layers could be obtained by electrodeposition from the CuCl-EMIC ionic liquid. The CuCl-EMIC ionic liquid with molar ratio of 1 had larger reduction peak current density. The NdFeB matrix was activated by the anodic current density of 20~30 mA/cm2, the surface became smoother and the voids were less. Copper coatings on NdFeB surface were more uniform and denser after activation, and the bonding force was more than 9.2 MPa. The porosity of copper coatings on NdFeB surface decreased with the increase of the coating thickness. When the thickness was 6 μm, the corrosion potential of the samples was similar to that of pure copper, and the porosity was 0.005 23%. By CuCl-EMIC ionic liquid with molar ratio of 1, the NdFeB matrix with smoother surface, fewer holes and no oxide film can be obtained by anodic activation, and the thin compact and uniform copper layer with good bonding can be electrodeposited on the surface of NdFeB.
Key words
ionic liquids; CuCl-EMIC; NdFeB; copper coating; anodic activation; porosity
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ZHUANG Chen, LING Guo-ping.
Electrodeposition of Copper on NdFeB in CuCl-EMIC Ionic Liquid[J]. Surface Technology. 2019, 48(9): 260-265
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