Development of Zn-bonded Sm-Fe-N permanent magnet and magnetic powders with high magnetic coercivity

我们试图用具有高磁各向异性和高居里温度的Sm-Fe-N化合物来制备高温高磁导率的永磁粉末。特别是，本工作是针对开发的磁性的Sm-Fe-N化合物粉末与锌膜，通过使用气相沉积和电化学沉积。1.以Sm-Fe-N和Zn粉为原料，确定了等离子烧结法制备高矫顽力材料的最佳温度、压力和时间条件。结果表明，在420 ℃、5, 000 kg/cm ^2、5 min条件下，等离子烧结获得了20 kOe的最大矫顽力。结果表明，等离子烧结是在短时间、低压力下获得高矫顽力的有力工具，2.对平均粒径为20 μ m的Sm-Fe-N粉末进行了镀锌处理（粗粉）和3 μ m（细粉），然后通过等离子烧结法烧结。结果表明，对粗粉进行镀锌可以提高磁粉的磁性，而对细粉则没有提高。3.对含Mn的Sm-Fe-N粉末进行了高分辨透射电镜观察，发现磁畴壁的钉扎是由直径约为10 nm的细晶粒晶体产生的。

We have tried to establish permanent powders with high magnetic coercivity at high temperatures by using the Sm-Fe-N compound, which has high magnetic anisotropy and high Curie tepmperature. In particular, the present work is directed toward the development of the magnetic coercivity by coating the powders of Sm-Fe-N compound with zinc films, by using vapor deposition and electro-chemical deposition. We have obtained as follows.1.We have determined optical conditions of temperature, pressure and time to prepare the high-coercivity material by the plasma sintering method, by using starting materials of the Sm-Fe-N and zinc powders. As a result we obtained the maximum coercivity of 20kOe at 420ﾟC,5,000kg/cm^2, and for 5 min. The result shows that the plasma sintering is a powerful tool to establish high coercivity in a short time and at a low pressure, compared with ordinary sintering methods.2.We have carried out zinc-coating the Sm-Fe-N powders with an average sizes of 20mum (rough powders) and 3mum (fine powders), by using vapor deposition and electro-chemical deposition, and then sintered by the plasma sintering method. As a result we have obtained the improvement of the magnetic coercivity by zinc coating for the rough powders, but no improvement for the fine powders. It is concluded that the development of new methods of zinc coating is necessary.3.We have succeeded in high-resolution transmission electron microscopy observations of Sm-Fe-N powders including Mn, which are expected to be high coercivity of pinning-type, and found that the pinning of magnetic domain walls is produced by fine-grained crystals with about 10 nm in diameter.