Study on Demagnetization and Magnetization to Reuse NdFeB-based Magnets

In this study, batch-type demagnetization heat-treatment conditions were studied via computational simulations to reuse waste NdFeB-based permanent magnets. t room temperature, the time delay for the Nd magnet specimen to reach the target temperature in the furnace There was a delay in the time required for the temperature of the specimen and the furnace temperature to reach the target temperature. This delay time was observed to decrease from 27 min to 12 min as the heat treatment temperature increased from 100℃ to 400℃. The magnetic fluxes of the Nd magnets decreased with an increase in the heat treatment temperatures, and the magnets demagnetized at 300℃. The completely demagnetized magnet was fully remagnetized when more than 6000 J of magnetizing energy was applied. Further, by analyzing the surface soundness of the demagnetized Nd magnet, it was confirmed that the magnet could be reused.