Ndfeb Permanent Magnet Material Preparation Process Optimization And Performance

Nd-Fe-B permanent magnet, with outstanding magnetic properties, is the most widely used and fastest-growing permanent magnet material recently. Both the obsolete equipments and backward technology lead to poor performance, consistency and stability. Based on this situation, we choose this project.In this work, Nd-Fe-B permanent magnet with high magnetic performance was prepared by promoting technology. The microstructure and particle size were characterized by scanning electron microscope (SEM) and laser particle size analyzer; the magnetic properties was studied by using AMT-4 automatic measurement instrument.HD technology with the traditional process were compared to make sure the powder particle size and distribution. The influence of sintering and tempering temperature on the microstructure and magnetic properties were studied.Small difference between Hcj and Hcb and high-Coercivity is obtained when ingot speed is 1.5m/s. HD process is useful for obtaining high-performance Nd-Fe-B magnets. Due to the reduced proportion of crystalline particles and nice magnetic orientation degree, high performance magnetic materials can be prepared. Meanwhile single-crystal particles which is also conducive to inhibit the formation of anti-magnetic core can improve the intrinsic coercivity. The more Uniform particle size distribution, the higher magnetic properties is.The remanence,coercivity and BH are very sensitive to the sintering temperature, and all of them reach the maximum value at 1105℃. Low-temperature tempering can significantly increase the coercivity, two-step tempering process is favorable for the overall magnetic properties. High coercivity is obtained when the samples are tempered for 2.5h at 600℃.The Ho is doped into Nd-Fe-B as Ho ore with low cost has similar magnetic properties with Nd-Fe-B. Coercivity with the increase of Ho element content decreases goes down very slowly. The coercivity and remanence is 13.8kOe(1098.48 kA·m-1) and 12.3kGs (1.23T) when 0.8wt% of the Ho is added. A large number of idle problems can be solved and the utilization of rare earth resources can be improved.Dy can form Dy2Fe14B by replacing Nd, The anisotropy field is much greater than the Dy2Fe14B the refined grain can inhibit a-Fe precipitation and result in high coercivity, The coercivity and remanence is 15.5kOe (1233.8 kA·m-1)and 12.1kGs(1.21T) when 1wt% of the Dy is added.