钕铁硼稀土永磁材料交流失磁  

Excitation loss in a Nd-Fe-B magnetic materials with alternating magnetic fields

作　　者：黄浩[1] 柴建云[2] 姜忠良[3] 陈秀云[3] 

机构地区：[1]清华大学料科学与工程系,北京100084 [2]清华大学电机工程与应用电子技术系,北京100084 [3]清华大学材料科学与工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2004年第6期721-724,共4页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目 ( 5 0 0 770 10 )

摘　　要：Nd- Fe- B稀土永磁材料的失磁现象制约了其在大型永磁电机中的应用。针对电机的实际工作环境 ,研究了不同工作状态的磁体在交变磁场作用下表面磁感应强度随时间的变化。研究发现 ,常温 2 5℃下磁体只有起始最低工作点低于其退磁曲线拐点时才会发生失磁现象 ,且随着磁场交变频率的升高 ,磁体失磁程度逐渐增大。并且运用磁体磁畴畴壁钉扎与运动模型和畴壁钉扎的热激活效应对实验现象进行了合理解释。这对 Nd- Fe-The loss of excitation limits the use of Nd-Fe-B permanent magnetic materials in large permanent magnets. The operating conditions in a permanent magnet were analyzed to quantity the magnetic induction changes on the surface with an alternating magnetic field. At normal temperatures (25 ℃), the loss of excitation occurs only when the initial excitation is below the inflexion of the demagnetization curve of the Nd-Fe-B material and higher alternating magnetic field frequencies cause the Nd-Fe-B material to more rapidly lose its excitation. The results were explained by the classical equation for the motion of a domain wall in ferromagnetic systems and by the thermal activation of magnetic domain walls from pinning sites. The result can be used to improve the design of Nd-Fe-B permanent magnets to control the loss of excitation.

关 键 词：永磁材料 钕铁硼 失磁 交变磁场 工作点 

分 类 号：TM273[一般工业技术—材料科学与工程]