RARE-EARTH MAGNET INDUSTRY IN JAPAN: CURRENT STATUS FUTURE TRENDS

摘要

After the development of Nd-Fe-B magnets, rare earth magnets are now essential components in many fields of technology, because of their ability to provide a strong magnetic flux. There are two, well-established techniques for the manufacture of rare earth magnets: powder metallurgy is used to obtain high performance, anisotropic, fully dense magnet bodies; and melt-spinning is widely used to produce magnet powders for isotropic bonded magnets. Another technique is the Hydrogenation, Disproportionation, Desorption, and Recombination (HDDR) process, which is effective for the production of high performance, anisotropic bonded magnet powders. In the industry of sintered Nd-Fe-B magnets in Japan, the total amount of production has increased about 20 % from year to year. The dominant application has been for voice coil motors (VCM), however, the total amounts has been decreasing because of down sizing of HDD. On the other hand, the applications for motors and communications are now increasing. In addition, the use for the motor in hybrid cars is considered as one of the most attractive applications in Japan. The total amount of bonded magnet production in Japan has also increased rapidly because of their use for small motors. In addition to the research of nanocomposite magnets, the research of Sm-Fe-N bonded magnet powders has been spread. Recently, high performance injection molded Sm-Fe-N magnets produced by RD method, whose (BH)_(max) over 15MGOe, has been developed. Mass production of anisotropic Nd-Fe-B bonded magnets with (BH)_(max) over 20MGOe produced using HDDR process or rapid solidification technology combined with plastic deformation process, has been announced. This article reviews the current status and future trend in the rare-earth magnet industry in Japan.