Recent developments of measurement of permanent magnetic materials

Recent advances of measurement of permanent magnetic materials in National Institute of Metrology (NIM) have been reviewed. A closed-magnetic-circuit hysteresisgraph has been built to investigate the sweep rate dependence of coercivity on permanent magnets. The linear relationship between coercivity...

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Bibliographic Details
Published in:Materials research innovations 2015-05, Vol.19 (sup3), p.S41-S45
Main Authors: Gong, W. J., Hou, R. F., Zhang, Z. G., He, J., Lin, A. L., Xu, Z. Y., Fan, W., Wang, J. P.
Format: Article
Language:English
Subjects:
Calibration
Coercive force
Coercivity
Constants
Helmholtz coils
Magnetic materials
Measurement
NdFeB
Orientation angle
Permanent magnets
Sweep rate
Three dimensional
Two dimensional
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Summary:Recent advances of measurement of permanent magnetic materials in National Institute of Metrology (NIM) have been reviewed. A closed-magnetic-circuit hysteresisgraph has been built to investigate the sweep rate dependence of coercivity on permanent magnets. The linear relationship between coercivity and logarithmic sweep rate has been found, and the maximum difference of H C in the sweep rate is 1·1%. The obtained thermal activation length is comparable with the characteristic length of the magnets and the underlying mechanisms are discussed. Then, the constant of Helmholtz coils has been calibrated by a new current method and the uncertainty of the value is
ISSN:1432-8917
1433-075X
DOI:10.1179/1432891715Z.0000000001424