The invention relates to the technical field of
rare earth permanent
magnet materials, in particular to a preparation process of a core-shell structure enhanced
neodymium iron
boron magnet. Through a multi-component composite formula of high-abundance
rare earth and a small amount of heavy
rare earth and in combination with a
magnesium interface catalytic pretreatment and
grain boundary diffusion technology, a Dy-rich shell layer is formed on the surface of a main phase grain, a core-shell structure is constructed, and the
coercivity and the high-temperature stability are remarkably improved. An integrated
continuous production technology is adopted in the preparation process and comprises the steps of vacuum melting, continuous
ingot casting, jet milling,
magnetic field forming and continuous
sintering,
laser-electrochemical integrated
machining is integrated, and high-precision
cutting and
surface corrosion prevention are achieved. The invention further relates to special equipment, such as a multi-zone intelligent
temperature control vacuum sintering furnace and double-shaft stirring-composite
magnetic field powder equipment, so that the temperature uniformity and the
powder orientation degree are ensured. According to the process, heavy rare earth dependence is reduced, the coercive force reaches 24 kOe or above, the high-temperature magnetic performance attenuation is smaller than or equal to 5%, the production cost is reduced, the efficiency is improved, and the process is suitable for the fields of motors,
electronics and the like.