1、 TECHNICAL REPORT IECTR 62331First edition 2005-02Pulsed field magnetometry Reference number IEC/TR 62331:2005(E) Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1. Consolidated
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7、arding this publication or need further assistance, please contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00 TECHNICAL REPORT IEC TR 62331First edition 2005-02Pulsed field magnetometry PRICE CODE IEC 2005 Copyright - all rights reserved No part of
8、 this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission, 3, rue de Varemb, PO Box 131, CH-1211 Geneva 20, Switzerland Telep
9、hone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmailiec.ch Web: www.iec.ch W For price, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission 2 TR 62331 IEC:2005(E) CONTENTS FOREWORD 4 INTRODUCTION 6 1 Scope and object7 2 Normative refe
10、rences .7 3 Pulsed field magnetometer (PFM).7 3.1 General principles .8 3.2 Size of test specimen 10 4 Field generator.10 4.1 General.10 4.2 Power supply.10 4.3 Magnetizing solenoid.14 5 Polarization and magnetic field strength sensors (pick-up coils) 14 5.1 General.14 5.2 The polarization sensor (J
11、 coil)15 5.3 The magnetic field strength sensor (H coil) 16 6 Transient instrumentation and digitizing hardware.16 6.1 General.16 6.2 Analogue integration and digitization .17 6.3 Digitization and numerical integration 17 6.4 Digitization rate .17 7 Data processing .17 7.1 Data processing elements .
12、18 7.2 Temperature23 7.3 Magnetic viscosity .25 7.4 Calibration.25 8 Comparison of measurements 29 8.1 Permeameter, “large magnet“ comparison29 8.2 Extraction method, ”small” test specimen comparison 30 8.3 Comparative measurement conclusions .33 9 Conclusion .33 Bibliography .34 Figure 1 M and H ti
13、me traces for a permanent magnet.9 Figure 2 J(H) and B(H) loop for a permanent magnet .9 Figure 3 Sine wave (decaying) electrical configuration .11 Figure 4 Unidirectional pulses (1/2 sine wave) electrical configuration12 Figure 5 Unidirectional pulses (decaying) electrical configuration .12 Figure
14、6 Three arrangements of J coil assembly configurations (drawing with permission of EMAJ ref. 30.15 Figure 7 M and H time traces and (H) plot of a “zero signal” 19 Figure 8 J(H) loops of a sintered NdFeB permanent magnet.23 TR 62331 IEC:2005(E) 3 Figure 9 J(H) loop including eddy currents of a conduc
15、tive bulk nickel specimen measurement result from a PFM system .27 Figure 10 Copper specimen eddy current measurement result27 Figure 11 J(H) loop for eddy current “corrected” nickel specimen .28 Figure 12 Results of a permeameter and a PFM measurement of a “large” specimen29 Figure 13 Detail of the
16、 1 stand 2 ndquadrants of the measurement results shown in Figure 12 “large magnet” 29 Figure 14 Comparison of a “small magnet” measured in a super-conducting, extraction method magnetometer (EMM) compared with a PFM measurement result of the same magnet 28 .30 Figure 15 Measurement result of a NEOM
17、AX 32EH NdFeB cylinder of diameter 10 mm length 7 mm on the TPM-2-10 system 34.31 Figure 16 Measurement result of a NEOMAX 32EH NdFeB cube of dimensions 7 mm 7 mm 7 mm 34.32 Figure 17 Measurement result of a sintered Sm2Co17 cylinder of diameter 10 mm and length 7 mm 3433 Table 1 Comparison of metho
18、ds of generating the magnetic field strength 13 Table 2 Classification of the influences of eddy currents.21 Table 3 A comparison of values taken from the measurement results presented in Figure 11 and Figure 1230 Table 4 Comparison of values measured in Figure 14 above (see NOTE) .30 4 TR 62331 IEC
19、:2005(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ PULSED FIELD MAGNETOMETRY FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promot
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28、on, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements
29、 of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. The main task of IEC technical committees is to prepare International Standards. However, a technical committee may propose the publication of a technical re
30、port when it has collected data of a different kind from that which is normally published as an International Standard, for example “state of the art“. IEC 62331, which is a technical report, has been prepared by IEC technical committee 68: Magnetic alloys and steels. The text of this technical repo
31、rt is based on the following documents: Enquiry draft Report on voting 68/299/DTR 68/303/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Di
32、rectives, Part 2. TR 62331 IEC:2005(E) 5 The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication
33、will be reconfirmed; withdrawn; replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. 6 TR 62331 IEC:2005(E) INTRODUCTION In order to measure the full magnetic characterization of magnetically hard (permanent magnet) materials, it is necess
34、ary to apply a magnetic field sufficient to saturate the test specimen of magnetic material. The generation of this magnetic field can become a practical limiting factor and can determine the appropriate measurement techniques. Super-conducting magnets can generate very high static or slowly changin
35、g magnetic fields but their complexity, high capital outlay and running costs, requiring cryogenic gases make them far from ideal. It is necessary to change fields slowly to avoid “quenching” the super- conducting magnet. Conventionally wound electro-magnets with slowly changing magnetic fields have
36、 a significant heat generation problem through I 2 R loss. This can be alleviated through the use of a high relative permeability “iron yoke”. However, saturation of the iron prevents maximum characterization of the loop of rare earth permanent magnet materials to be determined. A pulsed field syste
37、m utilizing conventional conductors minimizes heating effects by limiting field durations and by limiting heat generation to acceptable levels. Fields up to 40 Tesla (T) can be generated in this way. Careful consideration, however, must be given to the instrumentation and method to take account of d
38、ynamic effects due to the short duration of the magnetic field. While work on pulsed field magnetometry is carried out in many parts of the world, the two main groups are MACCHARETEC ref. 29 1in Europe and EMAJ ref. 30 in Japan. The approach adopted in Japan is one of supporting a standard with fixe
39、d specimen sizes, magnetic field strengths and frequencies in a limited number of configurations. 1References in square brackets refer to the bibliography. TR 62331 IEC:2005(E) 7 PULSED FIELD MAGNETOMETRY 1 Scope and object This Technical Report reviews methods for measuring magnetically hard materi
40、als using pulsed field magnetometers. The methods of measurement of the magnetic properties of magnetically hard materials have been specified in IEC 60404-5 for closed magnetic circuits and in IEC 60404-7 for open magnetic circuits. The measurement result of the magnetic properties of magnetically
41、hard materials at elevated temperatures is given in IEC 61807. Pulsed field magnetometers have been developed to provide rapid measurement facilities to match high speed production rates with 100 % quality control. The object of this report is to describe the principles and practical implications of
42、 pulsed field magnetometry in order to enable the full potential of the technique to be considered, including its application using small and large magnets of varying geometries, to various magnetic field strengths and frequencies. 2 Normative references The following referenced documents are indisp
43、ensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60404-5:1993, Magnetic materials Part 5: Permanent magnet (magnetically hard) materials Me
44、thods of measurement of magnetic properties IEC 60404-7:1982, Magnetic materials Part 7: Method of measurement of coercivity of magnetic materials in an open magnetic circuit IEC 61807:1999, Magnetic properties of magnetically hard materials at elevated temperatures Methods of measurement IEC 60404-
45、14:2002, Magnetic materials Part 14: Methods of measurement of the magnetic moment of ferromagnetic material specimen by the withdrawal or rotation method 3 Pulsed field magnetometer (PFM) A pulsed field magnetometer consists of the following parts: a) The magnetic field strength generator consistin
46、g of i) the power supply (usually a capacitive discharge system) ii) magnetizing solenoid b) Magnetization and magnetic field strength sensors (pick-up coils) c) Instrumentation for transient processing and digitizing hardware i) integration ii) digitization d) Data processing facilities to enable t
47、he processing of 8 TR 62331 IEC:2005(E) i) zero signal ii) M(H) loop positioning iii) self-demagnetization correction iv) low band pass filtering v) calibration factors vi) eddy current correction. 3.1 General principles The basic principle of operation of the pulsed field magnetometer depends upon
48、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. During a measurement cycle, the test specimen i
49、n the J coil increases flux. The output voltage of this coil is the time derivative of the flux coupled to that coil. This flux is due largely to the magnetization of the specimen but also to the zero signal (see 7.1.1) and possible eddy currents (see the eddy current correction techniques in 7.1.6) etc. As a consequence the coil is usually referred to as the “Jcoil,” or on occasions the “M coil
