Comparison of the corrosion resistances of chromium-passivated and cerium-passivated Zn/NdFeB magnets
Author:
Zhang Pengjie123, Chen Jing4, Yang Hongyi4, Xu Guangqing45, Lv Jun45, Cui Jiewu45, Sun Wei12, Li Bingshan12, Wang Dongmei45, Wu Yucheng45
Affiliation:
1. BGRIMM Technology Group Co, Ltd , Beijing 102600 , China 2. National Engineering Research Center for Magnetic Materials , Beijing 102600 , China 3. State Key Laboratory of Rare Earth Permanent Magnet Materials , Hefei 231500 , China 4. School of Materials Science and Engineering , Hefei University of Technology , Hefei 230009 , China 5. Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Anhui Provincial International S&T Cooperation Base for Advanced Energy Materials , Hefei University of Technology , Hefei 230009 , China
Abstract
Abstract
Chromium-free passivation of Zn coating on NdFeB magnets becomes a research hotspot due to the serious harm of chromium ions to the human body. Chromium-based and cerium-based passivation technologies are conducted on electroplating Zn/NdFeB respectively. Morphologies, elemental compositions and phase structures of the two passivated coatings are characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The corrosion resistances of the two passivated specimens are compared by neutral salt spray test, accelerated aging test and electrochemical measurements. A complete and smooth passivation film can be obtained on the surface of Zn/NdFeB, filling the gaps and pores in Zn coating. Compared with un-passivated Zn/NdFeB, Zn(Ce)/NdFeB and Zn(Cr)/NdFeB possess excellent corrosion resistance. In comparison, Zn(Ce)/NdFeB possesses excellent anti-corrosion performance, increasing the red-rust appearing time from 288 to 432 h, which is still lower than that of Zn(Cr)/NdFeB (528 h). Therefore, the self-repair effect of cerium passivation technology during the corrosion process should be further studied to achieve the purpose of replacing chromium passivation technology.
Funder
Hefei Municipal Natural Science Foundation The Key Project of BGRIMM Technology Group Co. Ltd The Key Research and Development Project of Anhui Province The Fundamental Research Funds for the Central Universities
Publisher
Walter de Gruyter GmbH
Subject
General Materials Science,General Chemical Engineering,General Chemistry
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