Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets
Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets
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DOI：
10.1016/j.jmmm.2016.11.105
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发表时间：
2017-03
影响因子：
2.7
通讯作者：
J. L. Xu;Q. Xiao;D. Mei;Z. Zhong;Y. Tong;Yufeng Zheng;Li Li-Li
中科院分区：
文献类型：
--
作者：
J. L. Xu;Q. Xiao;D. Mei;Z. Zhong;Y. Tong;Yufeng Zheng;Li Li-Li
采用微弧氧化技术在烧结NdFeB磁体表面制备了SiO2非晶涂层。采用扫描电子显微镜（SEM）、能量色散X射线能谱仪（EDS）、X射线光电子能谱仪（XPS）、动电位极化测试和物理性能测试系统（PPMS）研究了涂层的表面和横截面形貌、元素和相组成、耐腐蚀性和磁性能。结果表明，微弧氧化膜的表面形貌为珊瑚礁状结构，不同于典型的微弧氧化多孔结构。随着电压的增加，镀层厚度从12.72 μ m增加到19.90 μm，Si元素含量增加，Fe、Nd和P元素含量减少。涂层主要由非晶态SiO2和少量非晶态Fe2O3、Nd2O3组成。非晶态SiO2涂层具有良好的抗热震性，但随着电压的升高，涂层的抗热震性降低。涂层的耐蚀性随电压的增加而增加，与未涂层的NdFeB磁体相比，可提高一个数量级。微弧氧化膜层对NdFeB样品的磁性能有不同程度的降低。
Amorphous SiO2coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO2and a few amorphous Fe2O3and Nd2O3. The amorphous SiO2coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees.