3D printing of NdFeB bonded magnets with SrFe12O19 addition

Rectangular, square, ring and horseshoe-shaped NdFeB bonded magnets with SrFe12O19 addition have been prepared by additive manufacturing, also known as 3D printing. The prepared NdFeB slurries with ferrite addition were deposited to form shaped parts using a 3D printer. Highly loaded pseudo-plastic printing slurries were employed to print bonded magnets with 98% of theoretical density. In the printed magnets with 20 wt.% strontium ferrite (SrFe12O19), good dimensional accuracy and surface quality were obtained with a relatively low surface roughness of similar to 6 mu m. In addition, good coalescence without obvious defects or pores was observed, and the ultimate tensile strength was 12 MPa. The magnetic properties of the hybrid magnets decreased with the increase of SrFe12O19 content due to a lower volume fraction of the NdFeB powder and lower magnetic performance of the SrFe12O19 powder. Nevertheless, the coercivity temperature coefficient beta increased from -0.4%/degrees C to -0.2%/degrees C with the SrFe12O19 content increase to 20 wt.%, indicating better thermal stability of hybrid magnets. The proposed method of fabricating NdFeB bonded magnets significantly reduces the manufacturing cost of complex-shaped magnets, enables efficient utilization of rear earth elements and broadens elevated operating temperature applications. (C) 2018 Elsevier B.V. All rights reserved.