高保磁力Nd-Fe-B系焼結磁石の履歴曲線の精密測定に関する検討

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This paper reports the effects of the thermal fluctuation aftereffect and the eddy current on the measurement of hysteresis curves for high-coercivity Nd-Fe-B sintered magnets. Hysteresis curves were measured with a vibrating sample magnetometer using a superconducting magnet (SCM-VSM) and a pulsed field magnetometer (PFM) over a long period in the same maximum field of 4 MA/m. Spherical specimens with a diameter of 6.0 mm were used, and the demagnetization field was compensated for by using ademagnetizing factor N= 1/3. In this experiment, the anisotropy field value obtained from the intersection of the magnetization curves of an M-type Sr ferrite magnet sintered at 1240℃ was used for common magnetic field normalization. In the case of the SCM-VSM method, where the waiting time varied from 2 to 20 s, the difference in the H_<CJ> value was small. However, the difference in H_K was 40-90 kA/m. In a comparison of the SCM-VSM and PFM methods, the values of H_<CJ> and H_K in the PFM method showed increases of 30 and 90-190 kA/m, respectively. The eddy current influence strongly affected the measured value of H_K in the case of the PFM method. Hysteresis curves swelled under the influence of the eddy current.
社団法人日本磁気学会の論文
2003-09-01