IEC TR 63304 pdf – 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 pdf – Methods of measurement of the magnetic properties of permanent magnet (magnetically hard) materials in an open magnetic circuit using a superconducting magnet
1 Scope
This Technical Report describes the general principle and technical details of the methods ofmeasurement of the DC magnetic properties of permanent magnet materials in an openmagnetic circuit using a superconducting magnet (SCM).
This method is applicable to permanent magnet materials，such as those specified inIEC 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 fieldin the test specimen on the demagnetization curve measured in an open magnetic circuit.Themagnetic properties are determined from the corrected demagnetization curve.
NOTE These SCM-methods can determine the magnetic properties of permanent magnet materials with coercivityhigher than 2 MAm. The methods of measurement in a closed magnetic circuit specified in lEC 60404-5 can lead tosignificant measurementerror due to saturation effects in the pole pieces of yoke for the magneticmaterials withcoercivityhiligher than 1,6 MA/m (see IEC60404-5).
Normative references
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references, only the edition cited applies.
For undated’references,the latest edition of the referenced document (including anyamendments) applies.
IEC 60404-5，Magnetic materials – Part 5: Permanent magnet (magnetically hard) materials -Methods of measurement of magnetic properties
IEC 60404-8-1，Magnetic materials – Part 8-1: Specifications for individual materialsMagnetically hard materials
IEC 60050-121,International Electrotechnical Vocabulary – Part 121: Electromagnetism
IEC 60050-151,International Electrotechnical Vocabulary – Part 151: Electrical and magneticdevices
IEC 60050-221,International Electrotechnical Vocabulary – Chapter 221:Magnetic materialsand components
Terms and definitions
For the purposes of this document,the terms and definitions given in IEC 60050-121.lEC 60050-151,IEC 60050-221 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
IEC Electropedia: available at http://www.electropedia.org/
ISO Online browsing platform: available at http://www.iso.org/obp
3.1
demagnetization curve
part of a hysteresis loop in which the magnetic polarization goes from the remanent magnetic polarization to zero when the applied magnetic field strength varies monotonically, as illustrated in Figure 1
Note 1 to entry: A demagnetization curve can be measured from near magnetic saturation.
[SOURCE: IEC 60050-121:1998, 121-12-72, modified – magnetic flux density is replaced by magnetic polarization and Note 1 to entry and Figure 1 have been added]
3.2
magnetic dipole moment
m
vector quantity given by the volume integral of the magnetic polarization [SOURCE: IEC 60050-221:1990, 221-01-07, modified – the symbol j is changed to m which is
used industrially and the note has been removed]
3.3
M coil
detection coil for magnetic dipole moment
3.4
J coil
detection coil for magnetic polarization
4 General principle 4.1 Principle of the method Figure 2 illustrates schematic diagrams of typical test apparatuses. The test apparatus consists of a superconducting magnet (SCM), a moving device, a specimen rod, a magnetic field sensor (hereafter H sensor), a magnetic dipole moment detection coil (hereafter M coil), measuring devices and a data processing device (PC). The measurement is carried out in an open magnetic circuit to enable the determination of magnetic properties of permanent magnet materials with coercivity higher than 2 MA/m. The axis of the DC magnetic field generated by the SCM is vertical and coaxial with the M coil and the specimen rod. The moving test specimen is placed in a zone where the magnetic field strength is uniform with a tolerance of ±1 % at the centre of the SCM. The H sensor is placed in a zone where the influence of the magnetic dipole moment of the test specimen can be ignored. A test specimen is firmly attached on the specimen rod so that the direction of magnetization is parallel to the axis of the specimen rod, and then placed in the test apparatus as shown in Figure 2.