SmF₃/NdF₃复合夹层钕铁硼磁体结构和性能研究

Structural and Functional Analysis of NdFeB Magnets with SmF₃/NdF₃ Composite Sandwich Layers

摘要: 为了满足钕铁硼磁体在高温下运作的需求，减少磁体产生的涡流损耗，本文以夹层的方式制备了高电阻率的SmF₃/NdF₃复合钕铁硼磁体，探究了SmF₃/NdF₃复合粉添加量和比例对于钕铁硼磁体的电阻率、磁性能及力学性能的影响。研究表明，当SmF₃/NdF₃比例为3:1时，随着添加量的增加，磁体夹层的厚度提高，电阻率增大，磁能积和抗弯强度呈现下降趋势。当单位面积添加量达到6.52 × 10⁻⁴ g/mm²时，磁体电阻率增大到6.12 mΩ·cm，较未夹层的钕铁硼磁体电阻率146 μΩ·cm提高了一个数量级，但是磁体的最大磁能积和抗弯强度分别下降到39.61 MGOe/164 MPa；当保持夹层添加量不变，随着复合夹层中SmF₃占比减小，夹层粉体逸散现象减弱，磁体的电阻率增大，当复合夹层SmF₃/NdF₃比例为1:5时电阻率最高，为24.3 mΩ·cm；当复合夹层SmF₃/NdF₃比例为1:1时，磁体的磁能积最高为43.91 MGOe，复合SmF₃/NdF₃的比例对磁体的抗弯强度影响并不相同，当复合夹层SmF₃/NdF₃比例为3:1时抗弯强度提高到了270 MPa，较无夹层钕铁硼磁体抗弯强度254 MPa提高了6%。

Abstract: To meet the operational requirements of NdFeB magnets under high-temperature conditions and mitigate eddy current losses, this study fabricates high-resistivity SmF₃/NdF₃ composite NdFeB magnets via a laminated structure. The effects of SmF₃/NdF₃ composite powder contents and stoichiometric ratios on resistivity, magnetic properties, and mechanical performance were systematically investigated. Results demonstrate that at a SmF₃/NdF₃ ratio of 3:1, increasing additive contents enhances interlayer thickness and resistivity of the magnets, reaching 6.12 mΩ·cm when the additive content achieves 6.52 × 10⁻⁴ g/mm². While the magnetic energy product (BH)_max was reduced to 39.61 MGOe and flexural strength to 164 MPa. Notably, the achieved resistivity of 6.12 mΩ·cm represents a one-order-of-magnitude improvement compared to non-laminated NdFeB magnets, which exhibit a resistivity of 146 μΩ·cm. Under constant interlayer additive content, the reduction of SmF₃ proportion in the composite interlayer mitigates powder dispersion phenomena and enhances interlayer density, leading to increased resistivity. The resistivity reaches its maximum value of 24.3 mΩ·cm at a SmF₃/NdF₃ ratio of 1:5. The magnetic energy product peaks at 43.91 MGOe for a 1:1 SmF₃/NdF₃ ratio. The influence of SmF₃/NdF₃ ratios on flexural strength exhibits distinct trends, with the SmF₃/NdF₃ ratio of 3:1 demonstrating optimal mechanical performance. Specifically, the flexural strength increases to 270 MPa at a 3:1 ratio, representing a 6% enhancement compared to non-laminated NdFeB magnets (254 MPa).