RESEARCH PAPER |
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Magnetic Properties and Thermal Stability of Nd-Fe-B Magnets by Recycling Fabrication |
Toujun ZHOU1,Jiajie LI1,2,Chengjun GUO1,Yunfeng DING1,Jinshui CHEN1
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1 School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 2 Institute of Engineering and Research, Jiangxi University of Science and Technology, Ganzhou 341000 |
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Abstract The sintered Nd-Fe-B magnets were fabricated by short-circuit recycling process. The magnetic properties and thermal stability of the magnets with adding PrNd mixed rare earth were also investigated. The magnetic properties of the magnets with 2% PrNd addition were as follows: the remanence (Br) of 1.31 T, the coercivity (Hcj) of 1 474.86 kA/m, and the maximum energy product [(BH)max] of 353.90 kJ/m 3. Compared to the new qualified magnets, the Br, Hcj and (BH)max values of 95%, 102% and 90%, respectively, were recovered. The magnet thermal stability could be improved by PrNd addition. The temperature coefficient of the coercivity reduced from -0.589 9%/K to -0.556 4%/K in the range of 293—393 K. This is mainly because the addition of mixed rare earth PrNd enhances the demagnetization exchange coupling and the magnetocrystalline anisotropy field of the main phase. Thus the coercivity and thermal stability of the magnets are improved.
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Published: 25 January 2018
Online: 2018-01-25
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Samples No. | Br T | Hcj kA/m | (BH)max kJ/m3 | Hk/Hcj % | 1# | 1.38 | 1 447.01 | 353.90 | 94.5 | 2# | 1.29 | 1 374.62 | 319.67 | 75.9 | 3# | 1.32 | 1 436.67 | 325.09 | 63.9 | 4# | 1.31 | 1 474.86 | 319.99 | 68.5 |
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Magnetic properties of the sintered Nd-Fe-B magnets at room temperature
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Demagnetization curves of the sintered Nd-Fe-B magnets at room temperature
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Backscattered electron images of the sintered Nd-Fe-B magnets with various amounts of PrNd
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Elements | 1 | 2 | 3 | 4 | Nd | 21.68 | 68.22 | 21.44 | 72.23 | Pr | 3.08 | 12.54 | 6.02 | 11.54 | Fe | 66.85 | 0.98 | 66.57 | 0 | O | 0 | 9.47 | 0 | 10.70 | C | 2.12 | 6.15 | 1.71 | 5.54 |
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EDS analysis result (wt%) of 1,2,3 and 4 spots in Fig.2
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Samples | Temperature K | Br T | Hcj kA/m | (BH)max kJ/m3 | 2# | 293 | 1.29 | 1 374.62 | 319.67 | | 323 | 1.27 | 1 092.22 | 311.40 | 353 | 1.24 | 847.21 | 292.13 | 373 | 1.21 | 698.21 | 276.05 | 393 | 1.18 | 563.77 | 254.48 | 4# | 293 | 1.31 | 1 474.86 | 319.99 | | 323 | 1.26 | 1 186.89 | 301.13 | 353 | 1.23 | 937.89 | 282.50 | 373 | 1.20 | 785.95 | 267.77 | 393 | 1.17 | 654.30 | 249.86 |
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Magnetic properties of the sintered Nd-Fe-B magnets at 293 K,323 K,353 K,373 K and 393 K
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The variation of magnetic properties as a function of temperature of the sintered Nd-Fe-B
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