Thermal stability of anisotropic bonded magnets prepared by additive manufacturing

Abstract

In this research, anisotropic NdFeB + SmFeN hybrid and NdFeB bonded magnets are additively printed in a polyphenylene sulfide (PPS) polymer binder. Printed NdFeB + SmFeN PPS bonded magnets displayed excellent magnetic properties (Br [remanence] = 6.9 kG [0.69 T], Hcj [coercivity] = 8.3 kOe [660 kA/m], and BHmax [energy product] = 9.9 MGOe [79 kJ/m3]) with superior corrosion resistance and thermal stability. The anisotropic NdFeB bonded magnet shows a high coercivity of 14.6 kOe (1162 kA/m) with a BHmax of 8.7 MGOe (69 kJ/m3). The coercivity and remanence temperature coefficients for NdFeB + SmFeN hybrid bonded magnets are −0.10%/K and −0.46%/K, and for NdFeB bonded magnets are −0.14%/K and −0.53%/K in the range of 300–400 K, indicating that the hybrid bonded magnets are thermally stable. The average flux aging loss for hybrid magnets was also determined to be very stable over 2000 h at 448 K (175°C) in air with 2.04% compared to that of NdFeB magnets with 3.62%.

Recent Advances in Corrosion Inhibition of Bonded NdFeB Magnets

“…The effect is illustrated in Figure 3a-c. both NdFeB and SmFeN because the magnetic flux decreased by much less than 1% of the value measured for uncoated magnets [12]. after dipping in the acid solution for 24 h at room temperature, the uncovered NdFeB magnet partially corroded, so the saturated magnetization dropped to 98 emu, while the covered magnet remained intact; (c) after dipping in the acid solution for 100 h at 80 °C, the uncovered NdFeB magnet corroded significantly, so the saturated magnetization dropped to 32 emu, while the covered magnet remained intact.…”

“…The unfavorable results reported by Paranthaman et al [ 10 ] at larger temperatures between 100 and 200 °C may be explained by structural modification of this adhesive, as the highest recommended curing temperature is 93 °C. The same adhesive was also reported to be beneficial for coating hybrid magnets containing both NdFeB and SmFeN because the magnetic flux decreased by much less than 1% of the value measured for uncoated magnets [ 12 ].…”

“…The effect is illustrated in Figure 3a-c. same adhesive was also reported to be beneficial for coating hybrid magnets containing both NdFeB and SmFeN because the magnetic flux decreased by much less than 1% of the value measured for uncoated magnets [12]. An epoxy coating to improve the corrosion resistance of bonded NdFeB magnets was also applied by Yang et al [13].…”

Advanced multimaterial shape optimization methods as applied to advanced manufacturing of wind turbine generators

“…In terms of the BAAM process described in references, 20,22 the feedstock is obtained by first pelletizing the composite magnet powder (Sm-Fe-N and Nd-Fe-B suspended in polymer binder) and then extruded through a heated nozzle that precisely deposits each layer onto a build platform. Each layer thickness corresponds to the extruder's nozzle diameter.…”

“…The optimized magnet designs presented in this work can be produced by FDM 3D printing. ORNL's BAAM 3D printer has shown that it is possible to produce these magnets 20,22 because it can handle very high magnet filler loading. However, other commercially available printers may not be equipped to process the high-volume fraction material necessary for these magnets.…”