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This standard is drafted in accordance with rules given in GB/T 1.1-2009.
This standard is redrafted by reference to IEC TR 62331: 2005 "Pulsed Field Magnetometry" and not equivalent to IEC TR 62331: 2005.
This standard is proposed by the China Electrical Equipment Industry Association.
This standard is under the jurisdiction of National Standardization Technical Committee of Electrical Alloy (SAC/TC 228).
Chief drafting organizations of this standard: China National Institute of Metrology, Guilin Electrical Equipment Scientific Research Institute, China Jiliang University, Tianjin Sanhuan Lexi New Material Co., Ltd., Ningbo Jinji Strong Magnet Material Co., Ltd., Ningbo Ketian Magnet Co., Ltd., Ningbo Shengshida Magnetics Co,.Ltd.
Chief drafting staff of this standard: He Jian, Shu Kangying, Xie Yongzhong, Lin Anli, Liu Wuli, Hu Yuanhu, Wang Yuping, Fan Wen, Zheng Zhishou, Wang Zhanguo, Wang Xuelin.
Introduction
The electromagnet is recommended by GB/T 3217 "Permanent Magnet (Magnetically Hard) Materials-Methods of Measurement of Magnetic Properties" for the magnetization device of closed magnetic circuit and its pole head is recommended to be made of the magnetically soft material with high saturation magnetic polarization strength and high magnetic permeability and the magnetic flux density in the pole head shall be much lower than saturation magnetic flux density during the measurement. However, the saturation magnetic polarization strength can only reach 2.45 T when the pole head is made of the best ferrocobalt, i.e. the maximum field can only reach 1950kA/m, but much rare earth permanent magnet has an intrinsic coercivity (HcJ) greater than 2000 kA/m, therefore, the pole head of electromagnet will be in the hyper-saturated state during the measurement, in this case, the results will have large error, even stopping the measurement. For this kind of materials, the measurement method of generating higher magnetic field strength shall be used.
The vibrating sample magnetometer with superconductive magnetization device may generate a (6400~8000)kA/m quasi-static field but the application range of this method is limited due to the complicated technology, high purchasing and maintenance cost and the requirements for the low temperature environment by cooling with liquid helium.
The pulse field generator made of the general conducting material may reduce the heat effect generated by the coil to the acceptable level by limiting the pulse width, thereby obtaining the high and strong field. The cost to obtain the (16000~24000)kA/m high field by pulse field is much lower than that to obtain 4000 kA/m field by superconductive magnetization device, therefore, it is necessary to meet the measurement of all the permanent magnet materials with the lower cost.
Due to the dynamic effect caused by the pulse field, the effect of eddy current in the specimen must be considered fully in the application of the PFM method.
The design and manufacture of the PFM system is complicated but has many advantages to other methods, in particular, it has solved the problems of inaccurate measurement of the rare earth permanent magnet with intrinsic coercivity above 2000 kA/m by the methods in GB/T 3217. The publication of this standard will enable more engineering workers to use this method and this is the first step for it to become the international standard.
NATIONAL STANDARD
OF THE PEOPLE'S REPUBLIC OF CHINA
中華人民共和國國家標(biāo)準(zhǔn)
GB/T 29628-2013
Guides for Methods of Measurement of the Magnetic Properties of Permanent (Magnetically Hard) Materials by Pulsed Field Magnetometry
永磁(硬磁)脈沖測量方法指南
1 Scope
This standard specifies the methods for measuring magnetic properties of permanent (magnetically hard) materials using pulsed field magnetometers.
This standard is applicable to the measurement of the magnetic properties of permanent materials with high intrinsic coercivity like rare earth cobalt and Re-Fe-B.
The methods of measurement of the magnetic properties of magnetically hard material have been specified in this standard for open magnetic circuit and in GB/T 3217 for closed magnetic circuit. The measurement curve comparison of the same testee at the methods in this standard and GB/T 3217 is detailed in Appendix A.
2 Normative References
The following documents are indispensable for the application of this document. For dated references, only the dated edition applies. For undated references, the latest edition (including all the amendments) of the normative document applies.
GB/T 2900.60 "Electrotechnical Terminology - Electromagnetism" [IEC 60050(121)]
GB/T 3217 "Permanent Magnet (Magnetically Hard) Materials – Methods of Measurement of Magnetic Properties" (IEC 60404-5)
GB/T 9637 "Electrotechnical Terminology-Magnetic Materials and Components" [IEC 60050(221)]
IEC 60050(151) "International Electrotechnical Vocabulary - Part 151: Electrical and Magnetic Devices"
3 Terms and Definitions
For the purpose of this document, terms and definitions in GB/T 2900.60, GB/T 3217, GB/T 9637and IEC 60050(151) apply.
4 General Principle
The basic principle of operation of the pulsed field magnetometer depends upon an intense transient magnetic field being generated by the magnetic field strength generator and being applied to the test specimen to be measured. The magnetic field strength and resultant magnetization of the test specimen are recorded and processed and the hysteresis loop is obtained. See Figure 1 for the measuring principle.
Note: In the actual instrument, the test specimen is in the specimen coil which is located in the magnetizing solenoid.
Figure 1 Basic Principle for Permanent-magnetic Pulse Measurement
In Figure 1, the magnetic field is generated by the pulse magnetic field circuit composing of capacitor bank, semiconductor control circuit and magnetizing solenoid. During the measurement cycle, the test specimen is in the specimen coil which is located in the magnetizing solenoid and the tested specimen is magnetized by the pulse magnetic field. The specimen coil consists of magnetic polarization specimen coil (J coil) and magnetic strength specimen coil (H coil), for respectively inducing magnetic polarization and magnetic strength where the test specimen are located. The output voltage of the coil is the time derivative of the magnetic flux Ф. The magnetic polarization and magnetic strength signal are obtained after the output voltage is converted by the integral and module and two cycles are known as "J" channel and "H" channel. The J(H) hysteresis loop is obtained after the signal combination of the two channels.
The hysteresis loop shall be corrected for the self demagnetization of the open magnetic circuit measurement; the eddy current will be generated inside the magnetic body under the action of pulse magnetic field for the conductive test specimen and the eddy current effect will have an influence on the permanent magnet measurement, so the measuring result shall be subjected to the eddy current effect correction so that the intrinsical J(H) hysteresis loops identical with that at static state and closed magnetic circuit are obtained.
5 Size of Test Specimen
The results shown in this standard are for cylinders of a maximum dimensions of 30 mm diameter and 25mm length and minimum dimensions of 5 mm diameter and 5 mm length. The direct limitation is not required for the size of the test specimen due to measurement of the test specimen in the open magnetic circuit; if the eddy current effect is compensated, and the design of test instrument complies with the homogeneity range of magnetic field, the test specimen of different sizes are measurable.
Foreword I
Introduction II
1 Scope
2 Normative References
3 Terms and Definitions
4 General Principle
5 Size of Test Specimen
6 Basic Composition
7 Temperature Influence
8 Calibration
9 Reproducibility
10 Test Report
Appendix A (Informative) Comparison of Measurement
Bibliography
