四探针方法测量钕铁硼永磁体电阻率  

Measurement of Resistivity of NdFeB Magnet with Four-probe Method

作　　者：周博阳 任少卿 鲁富强 郝茜[1,2] 吕科 ZHOU Bo-yang;REN Shao-qing;LU Fu-qiang;HAO Qian;LYU Ke(State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization,Baotou 014030,China;Baotou Research Institute of Rare Earths,Baotou 014030,China)

机构地区：[1]白云鄂博稀土资源研究与综合利用全国重点实验室,内蒙古包头014030 [2]包头稀土研究院,内蒙古包头014030

出　　处：《稀土》2024年第2期136-142,共7页Chinese Rare Earths

基　　金：北方稀土企业项目(2020H2087,2020z2217,2021H2312)。

摘　　要：钕铁硼永磁材料电阻率的测量相关因素有粗糙度、厚度、面积、温度等等,准确设置以上条件是保证电阻率测量精确度的必要条件。利用四探针方法测量钕铁硼永磁体电阻率,无UPS电源的情况下,电阻率测量的最高值与最低值偏差为5%,加入UPS电源以后,电阻率测量的偏差为1.2%,偏差明显降低。当钕铁硼表面粗糙度为0.39μm时,电阻率测量值为139.84μΩ·cm,而当表面粗糙度为7.79μm时,电阻率测量值为147.20μΩ·cm。样品的电阻率随着样品厚度的增加而上升,当厚度在1 mm~5 mm范围内,所测量的电阻率随厚度增加而快速上升;厚度超过5 mm之后,电阻率呈现小平台内的波动。对于1 mm的探针间距,面积在20 mm×20 mm以上的样品才能满足测量要求。由厚度和面积相关的电阻率实验可以得知,测量样品尺寸越大,越利于测量的精确性。随着温度的升高,样品的电阻率有增加的趋势。但是对于M,H,SH牌号样品,200℃的电阻率均小于170℃的电阻率;对于UH牌号样品,电阻率的峰值则出现在110℃。Roughness, thickness, area dimension, temperature, etc are relevant factors for the measurement of resistivity of NdFeB permanent magnet. The appropriate setting of the above conditions is necessary to ensure the accuracy of resistivity measurement. Without UPS power supply, the deviation between the highest and lowest value of the resistivity measurement is 5%, while the UPS power supply is added, the deviation of the resistivity measurement is 1.2%, which is significantly reduced. When the roughness of NdFeB sample is only 0.39 μm, the measured value of resistivity is 139.84 μΩ·cm, and when the roughness is 7.79 μm, the measured value of resistivity is 147.20 μΩ·cm. As sample becomes thicker, the resistivity increases. When the thickness is in the range of 1 mm~5 mm, the measured resistivity rises rapidly with the increase in thickness;after the thickness exceeds 5mm, the resistivity exhibits fluctuations in a small platform. For a probe interval of 1 mm, samples with an area of 20 mm×20 mm or more can meet the measurement requirements. It can be known from the resistivity experiment related to thickness and area that the larger the sample size, the better the accuracy of the measurement. As the temperature increases, the resistivity of the sample has a tendency to increase. But for M, H, SH brand samples, the resistivity at 200 ℃ is less than 170 ℃;for UH brand sample, the peak value of resistivity appears at 110 ℃.

关 键 词：钕铁硼 电阻率 四探针法 涡流 

分 类 号：TM273[一般工业技术—材料科学与工程] TM930.12[电气工程—电工理论与新技术]