ASTM A1102-16
(Specification)Standard Specification for Sintered Samarium Cobalt (SmCo) Permanent Magnets
Standard Specification for Sintered Samarium Cobalt (SmCo) Permanent Magnets
ABSTRACT
This specification applies to technically important, commercially available, magnetically hard sintered (fully dense) permanent magnets commonly known as samarium cobalt (SmCo). SmCo permanent magnets are available in two general composition families abbreviated ‘SmCo 1:5’ and ‘SmCo 2:17.’ These materials have approximate magnetic properties of residual magnetic induction from 0.78 T (7800 G) to 1.18 T (11 800 G) and intrinsic coercivity typically greater than 800 kA/m (10 000 Oe). Special grades and isotropic (un-aligned) magnets can have properties outside these ranges. Specific magnetic hysteresis behavior (demagnetization curve) can be characterized using Test Method A977/A977M.
This specification includes requirements for the chemical composition of SmCo permanent magnets as well as their physical and mechanical properties, magnetic properties (maximum energy product, residual induction, coercive field strength, intrinsic coercive field strength), workmanship, finish, and appearance. It also covers sampling, certification, and packaging and package marking.
SCOPE
1.1 This specification covers technically important, commercially available, magnetically hard sintered (fully dense) permanent magnets commonly known as samarium cobalt. These materials are available in two general composition families abbreviated “SmCo 1:5” and “SmCo 2:17.” The numbers indicate the approximate atomic ratio of samarium to the sum of other constituents. (Refer to Appendix X3 for additional composition information.)
1.2 Samarium cobalt magnets have approximate magnetic properties of residual magnetic induction, Br, from 0.78 T (7800 G) to 1.18 T (11 800 G) and intrinsic coercivity, HcJ, typically greater than 800 kA/m (10 000 Oe). Special grades and isotropic (un-aligned) magnets can have properties outside these ranges (see Appendix X4). Specific magnetic hysteresis behavior (demagnetization curve) can be characterized using Test Method A977/A977M.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to customary (cgs-emu and inch-pound) units which are provided for information only and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:A1102 −16
Standard Specification for
1
Sintered Samarium Cobalt (SmCo) Permanent Magnets
This standard is issued under the fixed designation A1102; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Coercivity Permanent Magnet Materials Using Hyster-
esigraphs
1.1 This specification covers technically important, com-
2.2 Other Standards:
mercially available, magnetically hard sintered (fully dense)
MMPA Standard No. 0100-00 Standard Specifications for
permanent magnets commonly known as samarium cobalt.
3
Permanent Magnet Materials
These materials are available in two general composition
IEC 60404-8-1 Magnetic Materials Part 8: Specifications for
families abbreviated “SmCo 1:5” and “SmCo 2:17.” The
Individual Materials Section 1 – Standard Specifications
numbers indicate the approximate atomic ratio of samarium to
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for Magnetically Hard Materials
the sum of other constituents. (Refer to Appendix X3 for
additional composition information.)
3. Terminology
1.2 Samarium cobalt magnets have approximate magnetic
3.1 The terms and symbols used in this specification, unless
properties of residual magnetic induction, B , from 0.78 T
r
otherwise noted, are defined in Terminology A340.
(7800 G) to 1.18 T (11 800 G) and intrinsic coercivity, H ,
cJ
typically greater than 800 kA/m (10 000 Oe). Special grades 3.2 Terms that are not defined in Terminology A340 but are
and isotropic (un-aligned) magnets can have properties outside
in common usage and used herein are as follows.
these ranges (see Appendix X4). Specific magnetic hysteresis 3.2.1 Recoil permeability, µ , is the permeability corre-
(rec)
behavior (demagnetization curve) can be characterized using
sponding to the slope of the recoil line. For reference see
Test Method A977/A977M. incremental, relative, and reversible permeabilities as defined
in Terminology A340. In practical use, this is the slope of the
1.3 The values stated in SI units are to be regarded as
normal hysteresis loop in the second quadrant and in proximity
standard. The values given in parentheses are mathematical
to the B-axis. The value of recoil permeability is dimension-
conversions to customary (cgs-emu and inch-pound) units
less. Note that in producers’ product literature recoil perme-
whichareprovidedforinformationonlyandarenotconsidered
ability is sometimes represented by the symbol µ , which is
r
standard.
defined by Terminology A340 as relative permeability.
1.4 This standard does not purport to address all of the
3.2.2 Magnetic characteristics change with temperature.
safety concerns, if any, associated with its use. It is the
Two key metrics of permanent magnet performance are re-
responsibility of the user of this standard to establish appro-
sidual induction, B , and intrinsic coercive field strength, H .
r cJ
priate safety and health practices and determine the applica-
The change in these characteristics over a defined and limited
bility of regulatory limitations prior to use.
temperature range can be reversible, that is, nondestructive.
Thischangeisrepresentedbyvaluescalledreversibletempera-
2. Referenced Documents
ture coefficients. The symbol for reversible temperature coef-
2
2.1 ASTM Standards:
ficient of Induction is α(B ) and of (intrinsic) coercivity is
r
A340 Terminology of Symbols and Definitions Relating to α(H ). They are expressed in percent change per degree
cJ
Magnetic Testing
Celsius, %/°C, or the numerically equivalent percent per
A977/A977M Test Method for Magnetic Properties of High- Kelvin, %/K. The change in magnetic characteristics is
nonlinear, so it is necessary to specify the temperature range
over which the coefficient applies.
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This specification is under the jurisdiction of ASTM Committee A06 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
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Material Specifications. Available from the Permanent Magnet Division of the SMMA (www.sm-
Current edition approved Nov. 1, 2016. Published November 2016. DOI: ma.org). It was previously available from The International Magnetics Association
10.1520/A1102–16. (IMA). The IMA had been the successor to the MMPA and both organizations
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or (MMPA and IMA) no longer exist.
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contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from International Electrotechnical Commission (IEC), 3, rue de
Standards volume information, refer to the standard’s Document Summary page on Varembé, 1st Floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, http://
the ASTM website. www.iec.ch.
Copyri
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