烧结NdFeB永磁体表面微弧氧化涂层的制备及性能

Fabrication and properties of micro-arc oxidation coatings on sintered NdFeB permanent magnets

摘要:

为了提高烧结NdFeB永磁体的耐蚀性,本文在铝酸盐溶液中采用二步微弧氧化工艺在烧结NdFeB永磁体表面制备了氧化铝陶瓷涂层。微弧氧化过程中,电压-时间曲线可大致分为四个阶段,与阀金属处理的曲线基本一致。烧结NdFeB表面制备的涂层呈现出典型的微弧氧化多孔形貌,厚度大约为5 μm。涂层中仅含有Al₂O₃结晶相,并含有少量的Fe、Nd和P元素。微弧氧化处理后,烧结NdFeB的表面粗糙度有所增加,耐蚀性较基体提高了1个数量级。然后,微弧氧化处理后,烧结NdFeB磁体的剩磁和最大磁能积较未处理NdFeB有所下降。

Abstract:

In order to improve the corrosion resistance of the sintered NdFeB permanent magnets, Al2O3 ceramic coatings were prepared by a two-step micro-arc oxidation process in an aluminate solution. During the micro-arc oxidation process, the voltage-time curve could be divided into four regions consistent with the valve metals. The coating exhibited a typical micro-arc oxidation porous surface with the thickness of ~5 μm, and was only composed of Al2O3 crystalline phase with some Fe elements and a few Nd and P elements. The surface roughness of coated NdFeB magnets was higher than that of uncoated sample, while the corrosion resistance was enhanced by one order of magnitude. Unfortunately, the magnetic properties (remanence and maximum energy product) of coated NdFeB sample decreased in different degrees.