IEC TR 63304:2021
(Main)Methods of measurement of the magnetic properties of permanent magnet (magnetically hard) materials in an open magnetic circuit using a superconducting magnet
Methods of measurement of the magnetic properties of permanent magnet (magnetically hard) materials in an open magnetic circuit using a superconducting magnet
IEC TR 63304:2021(E) describes the general principle and technical details of the methods of measurement of the DC magnetic properties of permanent magnet materials in an open magnetic circuit using a superconducting magnet (SCM).
This method is applicable to permanent magnet materials, such as those specified in IEC 60404-8-1, the properties of which are presumed homogeneous throughout their volume.
There are two methods:
– the SCM-Vibrating Sample Magnetometer (VSM) method;
– the SCM-Extraction method.
This document also describes methods to correct the influence of the self-demagnetizing field in the test specimen on the demagnetization curve measured in an open magnetic circuit. The magnetic properties are determined from the corrected demagnetization curve.
NOTE These SCM-methods can determine the magnetic properties of permanent magnet materials with coercivity higher than 2 MA/m. The methods of measurement in a closed magnetic circuit specified in IEC 60404-5 can lead to significant measurement error due to saturation effects in the pole pieces of yoke for the magnetic materials with coercivity higher than 1,6 MA/m (see IEC 60404-5).
General Information
Standards Content (Sample)
IEC TR 63304 ®
Edition 1.0 2021-04
TECHNICAL
REPORT
Methods of measurement of the magnetic properties of permanent magnet
(magnetically hard) materials in an open magnetic circuit using a
superconducting magnet
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IEC TR 63304 ®
Edition 1.0 2021-04
TECHNICAL
REPORT
Methods of measurement of the magnetic properties of permanent magnet
(magnetically hard) materials in an open magnetic circuit using a
superconducting magnet
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20; 29.030 ISBN 978-2-8322-9714-8
– 2 – IEC TR 63304:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 General principle . 11
4.1 Principle of the method . 11
4.2 Superconducting magnet (SCM). 12
4.3 Magnetic field strength sensor (H sensor) . 13
4.4 Magnetic dipole moment detection coil (M coil) . 13
4.5 Specimen rod and moving device . 14
4.6 Measuring devices and the data processing device . 14
5 Test specimen . 14
6 Preparation of measurement . 15
6.1 Measurement of volume of the test specimen . 15
6.2 Initial magnetization of the test specimen to saturation . 15
7 Determination of magnetic polarization . 15
7.1 Measurement of the magnetic dipole moment . 15
7.2 Determination of magnetic polarization . 16
8 Measurement of magnetic field . 17
9 Calibration of the magnetic dipole moment detection coil (M coil) . 17
10 Determination of demagnetization curve . 17
11 Demagnetizing field correction . 18
11.1 General . 18
11.2 Method A: Method using a demagnetizing factor determined by the shape of
the test specimen only . 20
11.3 Method B: Method using a demagnetizing factor determined by the shape
and the magnetic susceptibility of the test specimen . 20
11.4 Method C: Method using an inverse analysis considering the spatial
distribution of the self-demagnetizing field strength in the test specimen . 21
12 Determination of principal magnetic properties . 21
12.1 Remanent magnetic polarization J . 21
r
12.2 Maximum energy product (BH) . 22
max
12.3 Coercivity (H and H ) . 22
cJ cB
13 Reproducibility . 22
14 Test report . 22
Annex A (informative) SCM-Magnetometer method . 24
Annex B (informative) Effects of the test specimen dimensions . 26
Annex C (informative) Superconducting magnets (SCMs) . 27
Annex D (informative) Magnetic dipole moment detection coils (M coils) . 29
Annex E (informative/normative) Details of the demagnetizing field correction . 31
E.1 General . 31
E.2 Symbols . 31
E.3 Method using a demagnetizing factor determined by the shape and magnetic
susceptibility of the test specimen (Method B). 32
E.4 Method using an inverse analysis considering the spatial distribution of the
self-demagnetizing field strength in the test specimen (Method C) . 34
Annex F (informative) Result of the international round robin test of magnetic
properties of permanent magnets using the SCM-VSM and SCM-Extraction methods . 39
F.1 General . 39
F.2 Protocol of the RRT . 39
F.3 Result of the RRT . 40
F.4 Reproducibility of the measurements . 43
Bibliography . 45
Figure 1 – Demagnetization curve J(H) . 10
Figure 2 – Schematic diagrams of the test apparatus . 11
Figure 3 – Schematic diagrams of the first order gradiometer coil . 13
Figure 4 – Relationship between magnetic polarization and self-demagnetizing field . 18
Figure 5 – Schematic diagram of the demagnetizing field correction . 19
Figure 6 – Conceptual diagram of the procedure of Method C . 21
Figure A.1 – Schematic diagram of the test apparatus for the SCM-Magnetometer
method . 24
Figure A.2 – Schematic diagrams of the test apparatus for the method in a closed
magnetic circuit in accordance with IEC 60404-5 . 25
Figure B.1 – Effects of test specimen dimensions on magnetic properties [B , H , H
r cJ cB
and (BH) ] for Nd-Fe-B sintered magnets with different coercivities . 26
max
Figure C.1 – Typical cross-sectional structure of the ceramic SCM . 28
Figure D.1 – Schematic diagram of the second order gradiometer coil for the SCM-
VSM method . 29
Figure D.2 – Schematic diagram of the dependence of induced voltage on the position
of the test specimen in the SCM-Extraction method . 30
Figure E.1 – Axes of a cuboid magnet . 32
Figure E.2 – Conceptual diagram of the procedure of Method C. 35
Figure E.3 – Flowchart of the procedure of Method C . 36
Figure E.4 – Comparison of the demagnetization curves corrected using demagnetizing
field correction Methods A, B and C . 38
Figure F.1 – Comparison of J measured by the laboratories . 40
r
Figure F.2 – Comparison of H measured by the laboratories . 41
cJ
Figure F.3 – Comparison of (BH) measured by the laboratories . 41
max
Figure F.4 – Comparison of hysteresis loops measured by the laboratories . 43
Figure F.5 – Relative standard deviation of J , H and (BH) . 44
r cJ max
Table 1 – Features of the demagnetizing field correction methods in comparison with
Method B . 20
Table 2 – Reproducibility of the magnetic properties . 22
– 4 – IEC TR 63304:2021 © IEC 2021
Table C.1 – Performance of SCMs . 27
Table F.1 – Nominal values of coercivity . 39
Table F.2 – Participating laboratories and their employed measuring methods . 40
Table F.3 – Comparison of magnetic properties measured by the laboratories . 42
Table F.4 – Comparison of the reproducibility . 44
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHODS OF MEASUREMENT OF THE MAGNETIC PROPERTIES OF
PERMANENT MAGNET (MAGNETICALLY HARD) MATERIALS IN AN OPEN
MAGNETIC CIRCUIT USING A SUPERCONDUCTING MAGNET
FOREWORD
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