Tridelta Magnetsysteme
A Tridelta Group Company
OERSTIT®– the material for high temperature
permanent magnets
Raw Materials
Magnets
Systems and Components
Many applications involving permanent magnets demand the highest
thermal stability. This is one of the
main reasons for the success of
Oerstit magnets from Tridelta. They
were developed around 50 years ago
and have been constantly improved
Magnetic characteristics
Material1)
Trade Name
Tridelta
Nomenclature
according to
DIN 17410/IEC 404-8-1
to a state-of-the-art technology
applied today in many varied operations. OERSTIT ® is a synonym for
valuable AlNiCo-materials, permitting the highest temperature operations. Nine common types are described in the following table.
(Magnetic characteristics vary with product geometry.)
Max. energy
product
Remanence
flux density
Normal
coercitivity
Intrinsic
coercitivity
(BH)max
kJ/m3 MGOe
Br
mT
HcB
kA/m
kOe
HcJ
kA/m
G
kOe
Rel. per. Operpermea- ating
bility
temperature2)
Tmax
µp
°C
Hs
kA/m
3.2
500
270
3.7
500
270
2.0
550
800
2.2
550
600
4.3
500
270
2.8
550
450
4.5
500
270
4.5
500
250
500
Oerstit 500 G3) a min 38
4.8
1190 11900
48
0.6
49
0.6
AlNiCo 38/5
typ 40
5.0
1240 12400
50
0.6
51
0.6
Oerstit 500 S
a min 36
4.5
1150 11500
47
0.6
48
0.6
AlNiCo 36/5
typ
38
4.8
1200 12000
49
0.6
50
0.6
Oerstit 1800
a min 39
4.9
700
7000 140
1.75
148
1.85
typ 43
5.4
730
7300 148
1.85
156
1.95
a min 39
4.9
820
8200 111
1.4
115
1.4
43
5.4
860
8600 120
1.5
125
1.6
a min 29
3.6
990
9900
56
0.7
58
0.7
AlNiCo 29/6
typ 32
4.0
1090 10900
58
0.7
60
0.8
Oerstit 260
i min 19
2.4
600
6000
95
1.2
102
1.3
typ 21
2.6
650
6500 100
1.3
107
1.4
Oerstit 160
i min 12
1.5
650
6500
53
0.7
57
0.7
AlNiCo 12/6
typ 14
1.8
700
7000
60
0.8
64
0.8
AlNiCo
Oerstit 450
AlNiCo 39/12 typ
Oerstit 400
AlNiCo 19/10
Oerstit 120
i min
8
1.0
480
4800
48
0.6
50
0.63
AlNiCo 8/5
typ
9
1.1
500
5000
52
0.65
54
0.68
Oerstit 60
i typ
5
0.6
850
8500
10
0,125
10
0,125 5.0
AlNiCo 5/1.2
1) a=anisotrope, i=isotrope, typ=typical values, min=minimum value
2) The maximum operating temperature depends on the system dimensions.
3) Cast magnet
2
Saturation
field
strength
Magnet production
Thermally stable Oerstit magnets
are produced either by foundry
methods of melting and casting the
metal alloys or by die-pressing and
sintering processes using metal
powders.
A family of Oerstit magnets derived
from the common based materials
can be produced in both isotropic
and anisotropic finishes. Their magnetic characteristics are extremely
dependent on the size and geometry
of the magnet. To form them, using
metallurgical powder processes,
the Oerstit powder mixture is first
pressed into forms in a matrix and
subsequently sintered under vacu-
um or inert gas at high temperatures. During this sintering process
the alloy itself is formed by element
diffusion.
The blank magnets are afterwards
homogenised, again at high temper a tures, and cooled down to
ambi ent temperature, the latter
step, especially, being strictly controlled. With anisotropic material
this takes place in an axial magnetic
field to induce preferential magnetic directionality. Finally, temperature treatment stabilises the end
product. All heat treatments are
carried out in inert gas environments to avoid oxidation.
Physical characteristics/Temperature-coefficient: TK (Br) = - 0,02 % /K
Material
Density
g/cm3
Oerstit
Elasticity
module
Deflection Compresstrength
sive
strength
Hardness
Electrical Specific Thermal
resisheat
conductivity
tivity
Curie
temperature
E
kN/mm2
FB
N/mm2
HRC
ρ
µ Ω/cm
Tc
°C
FP
N/mm2
c
J/kg K
λ
W/m K
Coefficient of linear
expansion
parallel vertical
to the pref. direction
⌬l/l
⌬l/l
10-6/K
10-6/K
6.9 -7.3 100 -200 250 -600 300 -400 ca. 50 45 -65 ca. 400 10 -100 820 -870 13 -14 13 -14
Magnet forms
It is possible to meet almost any
type of customer requirement. Restrictions, however, exist and are
related to the usual parameters of
casting and die-pressing processes.
Oerstit magnets are supplied as
3
blocks, cylinders, rings, segments or
other forms. Drilled holes, cavities
and keyseats for example are possible as long as they are aligned parallel to the press direction.
Average demagnetisation characteristic curves of Oerstit magnets at ambient temperature
B/μ0H
–10
–11
–12 –13 –14 –15
–20
J,B[T]
1.4
–25 –30
–9
G
t 500
Oersti
1.2
00 S
5
stit
Oer
–8
–7
O
–6
ti
e rs
O e rs
–5
1.0
00
t 4
50
tit 4
O e rs t i
0.8
t 1800
–4
0.6
Oe
rs
ti
BxH
kJm-3
45
40
35
30
25
20
60
Oe
it
rs t
12
0
0.4
Oerst it 60
2
stit
O er
0
16
t
0.2
10
0.0
–140
–120
–100
–80
–60
H [kA/m]
Oerstit
500 G, 500 S, 1800,
450, 400, 260,
160, 120,
60
4
–40
–20
0
Demagnetisation curves of Oerstit magnets
depending on temperature
B/μ0H
–8
–9
–10
–12
–15
J,B [T]
1.0
–20
–7
–6
25
0
30
0
50
–5
°C
°C
0.8
°C
0.6
0
70
–4
°C
0.4
BxH
kJm–3
35
30
25
20
B/μ0H
–20
–25
J,B [T]
1.4
–40 –50
0.2
10
–15
0.0
–128
–96
–64
H [kA/m]
–32
1.2
25 °C
0
300
°C
Oerstit 450
1.0
C
500 °
–10
650
0.8
°C
BxH
kJm–3
40
0.6
35
Temperature characteristics
Oerstit magnets are designed to
satisfy high thermal stability demands in many applications. The
magnetic characteristics and properties of Oerstit materials are well
known to be the least affected by
temperature changes when compared to other permanent magnetic
materials. This is the decisive advantage of Oerstit. It can be used in
thermal conditions of up to 550 °C.
30
0.4
25
15
0.2
0.0
–64
Oerstit 500 S
Indeed, some Oerstit types, above all
Oerstit 450, have been successfully
integrated into systems using temperatures even higher than 550 °C.
However, it must be remembered
that small changes in Oerstit properties do in fact occur even at lower
tem peratures, though they are
reversible.
5
–48
–32
H [kA/m]
–16
0
Toxicity
Oerstit magnets are non-toxic and
environmentally neutral.
Direct contact with foodstuffs is to
be avoided because of the cobalt
content, and laws relating to this.
For such applications Tridelta can
encase Oerstit magnets in a plastic
coating.
Chemical characteristics of Oerstit magnets in % weight
Material
Elements
AL
Co
Cu
Nb
Ni
Ti
Fe
Oerstit 500 G
8 -9
23 -25 3 -4
0 -1
13 -15 0 - 0,5
45 -53
Oerstit 500 S
8 -9
23 -25 3 -4
0 -1
13 -15 0 - 0,5
45 -53
Oerstit 1800
7 -9
35 -40 3 -4
0 -1
13 -15 6 - 8
25 -30
Oerstit 450
6 -8
30 -36 3 -4
0 -2
13 -15 4 - 6
30 -44
Oerstit 400
7 -9
25 -27 2 -4
0 -3
14 -16 0 -1
40 -52
Oerstit 260
6 -8
31 -34 3 -6
13 -15 6 - 9
28 -41
Oerstit 160
9 -18 15 -18 3 -5
20 -23 0 -1
42 -53
25 -27 0 -1
50 -53
16 -20
70 -75
Oerstit 120
11 -12
Oerstit 60
8 -10
4 -6
3 -4
Chemical resistance
Extensively resistant
Limited resistant
Non resistant
Organic solvents
Acetic acid
Anorganic acids
Motor oil
Hydrogen peroxide Tartaric acid
Petrol
Uric acid (10 %)
Alcohols
Citric acid
Sea water
Salts in aqueous solution
6
Processing tips
As a result of Oerstit magnets’ high
degree of brittleness, impact stress
should be avoided when screwing in
place or adding supports or reinforcing. When integrating hard ferrite with different types of material
their respective coefficients of expansion have to be taken into consideration. Magnetized magnets
attract iron swarf and dust. We
therefore recommend magnets are
magnetized after mounting.
Advice
Tridelta are delighted to pass on
their comprehensive experience and
provide competent, extensive customer-support for:
• the use, manufacture and further
processing of different materials,
• the choice of materials for the
most economical magnet form,
with reference to all the application requirements,
• interpretation of the magnetic
circuit. If required, the corresponding calculations can be done,
• magnetisation, purposeful
stabilisation and calibration of
magnet systems,
• quality assurance by measurement
and assessment of customerspecific specifications.
The earlier the co-operation begins,
the more efficiently Tridelta can
assist in decisive technical and economical optimisation of problem
solutions.
Quality assurance and delivery agreement
Maintaining and ensuring the highest possible standards of quality and punctual delivery are the bench marks for
the products and services offered by Tridelta. It is therefore only logical that Tridelta is DIN EN ISO 9001 certified, in
recognition of the success of their various activities.
Comprehensive quality assurance measures, at all levels, ensure the quality customers demand. All raw materials are
purchased solely from accredited sources. In production, all technical changes of phase are checked, corresponding
to type and product specific requirements. All finished products undergo visual and random sample function checks
to confirm product-specific electrical and magnetic parameters.
In practice, clear definition of the limits of the application, including mechanical composition, and a functional inspection system is recommended. For shape, form and size tolerances, the submitted technical drawing is definitive.
7
Tridelta Magnetsysteme
Tridelta Magnetsysteme GmbH
Ostkirchstrasse 177
D-44287 Dortmund
Phone: +49 (2 31) 45 01- 0
Fax: +49 (2 31) 45 01- 3 96
E-Mail: [email protected]
http://www.tridelta.de
Raw Materials
Magnets
Systems and Components
Order-No.: E 2.03.00 - 4.07 This publication may not be reproduced in whole or in parts without permission. All rights reserved. Printed in Germany.
A Tridelta Group Company