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| Salt Spray Corrosion Behavior of Environmentally Friendly Zn-Al Coatings on NdFeB Magnets |
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| DOI：10.7643/issn.1672-9242.2023.04.012 |
| KeyWord:Zn-Al coating NdFeB magnet salt spray corrosion corrosion mechanism self-corrosion potential electrochemical physical shielding |
| Author | Institution |
| HU Na |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| XIE Fa-qin |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| WU Xiang-qing |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| LI Shu-liang |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| HUANG Ke-chao |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| HE Dong-dong |
School of Civil Aviation, Northwestern Polytechnical University, Xi¢an , China |
| LU Chuang |
Ningbo Polytechnic, Ningbo , China |
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| Abstract: |
| The work aims to study the corrosion behavior of environmentally friendly Zn-Al coatings on NdFeB magnets in the salt spray environment. The morphology, phase and composition of Zn-Al coatings were analyzed by SEM, XRD, EDS, Raman spectroscopy, Fourier transform infrared spectroscopy and other methods. The corrosion behavior of Zn-Al coatings in the salt spray environment was studied with electrochemical curves. The corrosion time of the environmentally friendly Zn-Al coating prepared on the NdFeB magnet was not less than 1 000 hours. In the salt spray corrosion environment, the Zn-Al coating was gradually covered with white rust and lost its metallic luster; 1 126 hours later, there were red rust spots on the Zn-Al coating which showed honeycomb microstructure and microcracks. The corrosion products consisted of Zn5(OH)8Cl2∙H2O, Al9SiAl12(OH)18(AlO4)(Si5O16)Cl, Fe2O3 and a small amount of Zn and Al. In early corrosion, the passivation film and silane film on the Zn-Al coating played a protective role; as the corrosion developed, the film was destroyed, the flake metal powder was exposed and activated, and the coating acted as a sacrificial anode protective effect; In later corrosion, the corrosive medium penetrated the coating into the substrate through the micro-cracks. The protection and physical shielding of the coating¢s sacrificial anode were significantly weakened until failure. Environmentally friendly Zn-Al coatings can significantly improve the NSS corrosion resistance of NdFeb magnets. |
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