M-H characteristics and demagnetization resistance of samarium-cobalt permanent magnets to 300 C
M-H characteristics and demagnetization resistance of samarium-cobalt permanent magnets to 300 C
复制标题
300℃钐钴永磁体的M-H特性和抗退磁性能
DOI：
10.4271/929263
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发表时间：
1992
影响因子：
4.4
通讯作者：
J. Niedra
中科院分区：
文献类型：
--
作者：
J. Niedra
温度对永磁体M-H退磁特性的影响是在抗退磁永磁体器件中充分利用钐钴磁体高温性能的重要信息。在高温空间功率转换器中，如自由活塞式斯特林发动机驱动的直线交流发电机，磁体退磁可能是磁畴热搅拌和冶金变化的长期结果，也可能是外加磁场过大的直接结果。这里研究的是由基本M-H数据得出的外加磁场的短期退磁阻力。这个准静态退磁数据是从5个来源获得的，商业的，高本征矫直磁力，Sm2Co17型磁体，在23到300℃的温度范围内，使用电磁铁驱动的电子磁滞仪来测试1厘米立方体样品。观测到的第二象限M-H特性的变化是典型的M-矫顽力的快速损失，而剩磁的损失随温度的升高相对较小。第二象限M-H曲线拐点被用来定义在给定的温度下磁通密度摆动时，由于过大的屈曲场而导致的不可逆退磁的操作安全极限。这样的安全作业区图显示了不同来源样品的高温能力。对于大多数样品，它们的第二象限M-H环方形度随着温度的升高而增加，在250℃以上达到峰值或平台值。
The influence of temperature on the M-H demagnetization characteristics of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperatures in demagnetization-resistant permanent magnet devices. In high temperature space power converters, such as free-piston Stirling engine driven linear alternators, magnet demagnetization can occur as a long-term consequence of thermal agitation of domains and of metallurgical change, and also as an immediate consequence of too large an applied field. Investigated here is the short-term demagnetization resistance to applied fields derived from basic M-H data. This quasistatic demagnetization data was obtained for commercial, high-intrinsic-coercivity, Sm2Co17-type magnets from 5 sources, in the temperature range 23 to 300 C. An electromagnet driven, electronic hysteresigraph was used to test the 1-cm cubic samples. The observed variation of the 2nd quadrant M-H characteristics was a typical rapid loss of M-coercivity and a relatively lesser loss of remanence with increasing temperature. The 2nd quadrant M-H curve knee point is used to define the limits of operation safe against irreversible demagnetization due to an excessive bucking field for a given flux density swing at temperature. Such safe operating area plots are shown to differentiate the high temperature capabilities of the samples from different sources. For most of the samples, their 2nd quadrant M-H loop squareness increased with temperature, reaching a peak or a plateau above 250 C.