IEC TR 62518:2009

Rare earth sintered magnets - Stability of the magnetic properties at elevated temperatures

IEC/TR 62518:2009(E) describes the temperature behaviour of rare earth sintered magnets in detail for use in designing magnetic circuits exposed to elevated temperatures. The temperature behaviour of SmCo5, Sm2Co17 and Nd-Fe-B sintered magnets is described. The various changes of open circuit flux which can occur due to temperature are discussed in Clause 4. The long term stability of the magnets is discussed in Clause 5. The experimental procedures are described in Clause 6. Results of the measurements of the flux loss occurring at the ambient temperature after heating isothermally at 50 °C, 75 °C, 100 °C, 125 °C, 150 °C and 200 °C for up to 1000 h are given in Clause 7. The effect of length to diameter ratio (L/D) of the magnet samples and the influence of HcJ on the flux loss were also studied. The results are discussed in Clause 8. The data in this technical report was provided by the Institute of Electrical Engineers of Japan (IEEJ) and its subcommittees. This data has been gathered from the members of these sub-committees. The temperature stability correlated with the complex corrosion behaviour and the spin re-orientation phenomena at cryogenic temperatures will not be given in this technical report.

General Information

• Status: Published
• Publication Date: 16-Mar-2009
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Drafting Committee: WG 5 - TC 68/WG 5
• Current Stage: PPUB - Publication issued
• Start Date: 15-Jun-2009
• Completion Date: 17-Mar-2009

Standards Content (Sample)

IEC/TR 62518 ®
Edition 1.0 2009-03
TECHNICAL
REPORT
Rare earth sintered magnets – Stability of the magnetic properties at elevated
temperatures
IEC/TR 62518:2009(E)
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IEC/TR 62518 ®
Edition 1.0 2009-03
TECHNICAL
REPORT
Rare earth sintered magnets – Stability of the magnetic properties at elevated
temperatures
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 29.030 ISBN 978-2-88910-753-7
– 2 – TR 62518 © IEC:2009(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Classification of magnetic flux loss due to temperature.9
4.1 Reversible flux loss .9
4.2 Irreversible flux loss .9
4.3 Permanent flux loss.9
5 Long term ageing of rare earth magnets .10
6 Experimental .11
7 Temperature stability.13
7.1 Flux change due to temperature .13
7.2 Effect of temperature on B and H (demagnetization curves at different
r cJ
temperatures).14
7.3 The time effects at constant temperature (influence of temperature exposure
and L/D) .16
7.4 The influence of H on the irreversible flux loss for Sm Co magnets .18
cJ 2 17
7.5 The influence of H on the irreversible flux loss for Nd-Fe-B magnets .20
cJ
7.6 Irreversible flux loss per decade.22
7.7 Permanent flux loss.22
8 Summary.24
Annex A (informative) Summary of temperature stability graphs.25
Annex B (informative) Non-linearity of temperature dependence of B and H .26
r cJ
Bibliography.27

Figure 1 – Change of magnetic flux density operating on a load line during elevated
temperature ageing after R. Tenzer (schematic) [7, 8] .10
Figure 2 – Long term ageing of rare earth magnets (schematic) [9].11
Figure 3 – Measuring system of open circuit flux utilizing a fluxgate type digital
integrating fluxmeter [13] .
Figure 4 – Temperature dependence of flux for SmCo magnet (L/D = 0,7) [16] (See

Table 1) .14
Figure 5 – Temperature dependence of flux for Sm Co magnet (L/D = 0,7) [16] (See
2 17
Table 1) .14
Figure 6 – Temperature dependence of flux for Nd-Fe-B magnet (L/D = 0,7) [17] (See
Table 1) .
Figure 7 – J-H demagnetization curves of Nd-Fe-B magnet measured at different
temperatures [18] .14
Figure 8 – J-H demagnetization curves of Nd-Fe-B magnet measured at different
temperatures [19] .15
Figure 9 – Temperature dependence of normalized B and H for SmCo , Sm Co

r cJ 5 2 17
and Nd-Fe-B magnets [19] .
Figure 10 – Time dependence of irreversible flux loss for SmCo magnet exposed at
different temperatures [22].16
Figure 11 – Time dependence of irreversible flux loss for SmCo magnets with various
L/Ds [24].16

TR 62518 © IEC:2009(E) – 3 –
Figure 12 – Time dependence of irreversible flux loss for Sm Co magnet exposed at
2 17
different temperatures (Material 1) [22] .17
Figure 13 – Time dependence of irreversible flux loss for Sm Co magnets with
2 17
various L/Ds (Material 2) [24].17
Figure 14 – Time dependence of irreversible flux loss for Nd-Fe-B magnet exposed at
different temperatures [23].17
Figure 15 – Temperature dependence of irreversible flux loss after exposure for 100 h
for Nd-Fe-B magnets with various L/Ds [25] .17
Figure 16 – Time dependence of irreversible flux loss for a Sm Co magnet with H
2 17 cJ
= 0,48 MA/m and L/D = 0,7 [26] .19
Figure 17 – Time dependence of irreversible flux loss for a Sm Co magnet with H
2 17 cJ
= 1,19 MA/m and L/D = 0,7 [27] .19
Figure 18 – Time dependence of irreversible flux loss for a Sm Co magnet with H
2 17 cJ
= 1,97 MA/m and L/D = 0,7 [28] .19
Figure 19 – Time dependence of irreversible flux loss for a Nd-Fe-B magnet with H =
cJ
1,16 MA/m and L/D = 0,7 [30] .20
Figure 20 – Time dependence of irreversible flux loss for a Nd-Fe-B magnet with H =
cJ
1,66 MA/m and L/D = 0,7 [31] .20
Figure 21 – Time dependence of irreversible flux loss for a Nd-Fe-B magnet with H =
cJ
2,17 MA/m and L/D = 0,7 [32] .21
Figure 22 – Time dependence of irreversible flux loss for a Nd-Fe-B magnet with H =
cJ
2,45 MA/m and L/D = 0,7 [33] .21
Figure 23 – Comparison of irreversible flux loss for Sm Co magnets with different
2 17
H 21
cJ
Figure 24 – Comparison of irreversible flux loss for Nd-Fe-B magnets with different H .21
cJ
Figure 25 – Relationship between irreversible flux loss per decade and initial flux loss .23
Figure B.1 – Temperature dependence of normalized B and H to show the non-
r cJ
linearity (see data for Nd-Fe-B magnets in Figure 9) .26

Table 1 – Magnetic properties of the rare earth magnets employed for the open circuit
flux measurements to determine the reversible temperature coefficient of the magnetic
flux .13
Table 2 – Reversible temperature coefficient of the magnetic flux determined by
temperature cycling .13
Table 3 – Temperature coefficients of B and H for SmCo , Sm Co and Nd-Fe-B
r cJ 5 2 17
magnets (temperature range for the coefficient: 25 °C to 150 °C) .16
Table 4 – Magnetic properties of the specimens for the experiments to evaluate the
effects of temperature and L/D on irreversible flux loss.18
Table 5 – Magnetic properties of the Sm Co magnets for the experiment to evaluate
2 17
the influence of H on the irreversible flux loss .20
cJ
Table 6 – The magnetic properties of Nd-Fe-B magnets for the evaluation of the
influence of H on irreversible flux loss measured by a pulse recording fluxmeter .22
cJ
Table 7 – The permanent flux loss of Sm Co magnets after exposure for 1 000 h at
2 17
different temperatures.23
Table 8 – The permanent flux loss of Nd-Fe-B magnets after exposure for 1 000 h at
different temperatures.23
Table 9 – Basic magnetic properties of the three intermetallic compounds.24
Table A.1 – Summary of temperature stability graphs .25

– 4 – TR 62518 © IEC:2009(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RARE EARTH SINTERED MAGNETS –
STABILITY OF THE MAGNETIC PROPERTIES
AT ELEVATED TEMPERATURES
FOREWORD
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