Nd₂Fe₁₄B sintered magnets are used in the drive motors of
hybrid, electric and other vehicles. A magnet in which rare earth
content is reduced by means of a localized diffusion method has
been developed in order to reduce the volume of dysprosium.
The distribution of the demagnetization fields in a motor is not
uniform, so the necessary coercivity distribution for the magnets
was quantified using Computer-Aided Engineering (CAE). Then
material specifications of the localized dysprosium diffusion
satisfied with this coercivity distribution was determined, and
optimal manufacturing conditions including the position of
dysprosium diffusion were set. The coercivity distribution in every
position of the magnet using localized diffusion method was
inspected. As a result, the magnet was satisfied with coercivity
distribution demanded by CAE.
Furthermore, evaluation of motor characteristics, especially the
demagnetizing characteristic concerned with dysprosium reduction,
showed this developed magnet to possess identical characteristics
to a conventional magnet.
Dysprosium resources represent a particular issue among the rare
earths more generally, and the technology developed in this project
is able to reduce dysprosium use in magnets by approximately 30%
without compromising motor performance.
