Using electrophoretic deposition(EPD)method,the TbF_(3)powders were deposited on the surface of sintered Nd-Fe-B magnets,and the effects of MgCl_(2)on electrophoretic deposition and grain boundary diffusion were inves...Using electrophoretic deposition(EPD)method,the TbF_(3)powders were deposited on the surface of sintered Nd-Fe-B magnets,and the effects of MgCl_(2)on electrophoretic deposition and grain boundary diffusion were investigated.The results show that addition of 5 wt%MgCl_(2)can significantly improve the EPD efficiency and improve the adhesion of the coating by releasing local stress through the formation of special gully morphology.Combining with Biesheuvel equation,the effects of suspension concentration,voltage and time on EPD amount were studied.The Biesheuvel equation can be simplified asγ=AUSct/L,and A(=0.0141-0.0144)in this experiment was calculated to achieve the quantitative calculation of EPD amount.After heat treatment of 875℃×10 h+500℃×1 h,the coercivity of 48H(7 mm)sintered magnet with 0.3 wt%TbF_(3)increases from 18.5 to 22.4 kOe,with an increase of 21.1%.The core-shell structure was observed by a back-scattered scanning electron microscope(BSE-SEM),which proves that the addition of MgCl_(2)has no adverse effect on the grain boundary diffusion of Nd-Fe-B sintered magnets.展开更多
Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under va...Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under various wheel velocities to investigate the influence of Nb doping for the compounds. It is found that TbCu7-type structure is able to be obtained even though the wheel velocity is reduced to 20 m/s（x = 0.3）. An significant increase（△T_c=70 ℃） of the Curie temperature is obtained with Nb doping at x = 0.1 due to the lattice expansion revealed by Rietveld analysis. The optimum coercivity with the value H_（cj） of 810 kA/m is achieved at x = 0.2 in the nitrides, in which a reasonable distribution of grain sizes of both TbCu_7-type SmFe_9 N_δ and α-Fe can be found. However, an excess of Nb doping may lead to the increase of the weight fraction of α-Fe, which in turn deteriorates the magnetic properties.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB3500201,2021YFB3500202)the Beijing Youth Top-Notch Team Support Project of China(2018000021223TD10)+2 种基金the Beijing NOVA Program(Z211100002121092)the Natural Science Foundation of Hebei Province(E2021103006)the Hebei Province International Science and Technology Cooperation Base Construction Project of China(20591002D)。
文摘Using electrophoretic deposition(EPD)method,the TbF_(3)powders were deposited on the surface of sintered Nd-Fe-B magnets,and the effects of MgCl_(2)on electrophoretic deposition and grain boundary diffusion were investigated.The results show that addition of 5 wt%MgCl_(2)can significantly improve the EPD efficiency and improve the adhesion of the coating by releasing local stress through the formation of special gully morphology.Combining with Biesheuvel equation,the effects of suspension concentration,voltage and time on EPD amount were studied.The Biesheuvel equation can be simplified asγ=AUSct/L,and A(=0.0141-0.0144)in this experiment was calculated to achieve the quantitative calculation of EPD amount.After heat treatment of 875℃×10 h+500℃×1 h,the coercivity of 48H(7 mm)sintered magnet with 0.3 wt%TbF_(3)increases from 18.5 to 22.4 kOe,with an increase of 21.1%.The core-shell structure was observed by a back-scattered scanning electron microscope(BSE-SEM),which proves that the addition of MgCl_(2)has no adverse effect on the grain boundary diffusion of Nd-Fe-B sintered magnets.
文摘Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under various wheel velocities to investigate the influence of Nb doping for the compounds. It is found that TbCu7-type structure is able to be obtained even though the wheel velocity is reduced to 20 m/s（x = 0.3）. An significant increase（△T_c=70 ℃） of the Curie temperature is obtained with Nb doping at x = 0.1 due to the lattice expansion revealed by Rietveld analysis. The optimum coercivity with the value H_（cj） of 810 kA/m is achieved at x = 0.2 in the nitrides, in which a reasonable distribution of grain sizes of both TbCu_7-type SmFe_9 N_δ and α-Fe can be found. However, an excess of Nb doping may lead to the increase of the weight fraction of α-Fe, which in turn deteriorates the magnetic properties.
