ASTM B922-17
(Test Method)Standard Test Method for Metal Powder Specific Surface Area by Physical Adsorption
Standard Test Method for Metal Powder Specific Surface Area by Physical Adsorption
SIGNIFICANCE AND USE
5.1 Both suppliers and users of metals can benefit from knowledge of the surface area of these materials. Results of many intermediate and final processing steps are controlled by, or related to, specific surface area of the metal. The performance of many sintered or cast metal structures may be predicted from the specific surface area of the starting metal powder, or all or a portion of the finished piece.
SCOPE
1.1 This test method covers determination of surface area of metal powders. The test method specifies general procedures that are applicable to many commercial physical adsorption instruments. The method provides specific sample outgassing procedures for listed materials. It includes additional general outgassing instructions for other metals. The multipoint equation of Brunauer, Emmett and Teller (BET),2 along with the single point approximation of the BET equation, forms the basis for all calculations.
1.2 This test method does not include all existing procedures appropriate for outgassing metallic materials. The procedures included provided acceptable results for samples analyzed during interlaboratory testing. The investigator shall determine the appropriateness of listed procedures.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 State all numerical values in terms of SI units unless specific instrumentation software reports surface area using alternate units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report surface area as m2/g, instead of using correct SI units (m2/kg).
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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Designation:B922 −17
Standard Test Method for
1
Metal Powder Specific Surface Area by Physical Adsorption
This standard is issued under the fixed designation B922; 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* B243 Terminology of Powder Metallurgy
1.1 This test method covers determination of surface area of
3. Terminology
metal powders. The test method specifies general procedures
3.1 Definitions:
that are applicable to many commercial physical adsorption
3.1.1 Refer to Terminology B243 for additional terms spe-
instruments. The method provides specific sample outgassing
cific to metal powders.
procedures for listed materials. It includes additional general
3.2 Definitions of Terms Specific to This Standard:
outgassing instructions for other metals. The multipoint equa-
3.2.1 adsorbate, n—material that has been retained by the
2
tion of Brunauer, Emmett and Teller (BET), along with the
process of adsorption.
single point approximation of the BET equation, forms the
3.2.2 adsorbent, n—any solid having the ability to concen-
basis for all calculations.
trate or collect significant quantities of other substances on its
1.2 This test method does not include all existing proce-
surface.
dures appropriate for outgassing metallic materials. The pro-
3.2.3 adsorption, n—a process in which fluid molecules are
cedures included provided acceptable results for samples
concentrated or collected on a surface by chemical or physical
analyzed during interlaboratory testing. The investigator shall
forces, or both.
determine the appropriateness of listed procedures.
3.2.4 adsorptive, n—any substance available for adsorption.
1.3 The values stated in SI units are to be regarded as
3.2.5 outgassing, n—the evolution of gas from a material in
standard. No other units of measurement are included in this
a vacuum or inert gas flow, at or above ambient temperature.
standard.
1.3.1 State all numerical values in terms of SI units unless 3.2.6 physical adsorption (van der Waals adsorption),
specific instrumentation software reports surface area using
n—the binding of an adsorbate to the surface of a solid by
alternate units. In this case, present both reported and equiva- forces whose energy levels approximate those of condensation.
lentSIunitsinthefinalwrittenreport.Manyinstrumentsreport
3.2.7 surface area, n—the total area of the surface of a
2 2
surface area as m /g, instead of using correct SI units (m /kg).
powder or solid including both external and accessible internal
1.4 This standard does not purport to address all of the surfaces (from voids, cracks, open porosity, and fissures). The
safety concerns, if any, associated with its use. It is the area may be calculated by the BET (Brunauer, Emmett, and
responsibility of the user of this standard to establish appro- Teller) equation from gas adsorption data obtained under
priate safety and health practices and determine the applica- specific conditions. It is useful to express this value as the
bility of regulatory limitations prior to use. specificsurfacearea,forexample,surfaceareaperunitmassof
2
sample (m /kg).
2. Referenced Documents
3.2.8 surface area (BET), n—the total surface area of a solid
3
2.1 ASTM Standards:
calculated by the BET (Brunauer, Emmett, Teller) equation,
B215 Practices for Sampling Metal Powders
from nitrogen adsorption or desorption data obtained under
specific conditions.
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal
3.2.9 surface area, specific, n—the area, per unit mass of a
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.03 on Refractory Metal Powders.
granular or powdered or formed porous solid, of all external
Current edition approved Jan. 1, 2017. Published February 2017. Originally
plus internal surfaces that are accessible to a penetrating gas or
approved in 2002. Last previous edition approved in 2010 as B922–10. DOI:
liquid.
10.1520/B0922-17.
2
Brunauer, S., Emmett, P. H., and Teller, E. “Adsorption of Gases in Multimo-
4. Summary of Test Method
lecular Layers.” Journal of the American Chemical Society, Vol. 60, 1938, pp.
309-319.
4.1 An appropriately sized sample (to provide at least the
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
minimum surface area required for reliable results for the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
instrument used) is outgassed under appropriate conditions
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. prior to analysis.
*A Summ
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B922 − 10 B922 − 17
Standard Test Method for
1
Metal Powder Specific Surface Area by Physical Adsorption
This standard is issued under the fixed designation B922; 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*
1.1 This test method covers determination of surface area of metal powders. The test method specifies general procedures that
are applicable to many commercial physical adsorption instruments. The method provides specific sample outgassing procedures
for listed materials. It includes additional general outgassing instructions for other metals. The multipoint equation of Brunauer,
2
Emmett and Teller (BET), along with the single point approximation of the BET equation, forms the basis for all calculations.
1.2 This test method does not include all existing procedures appropriate for outgassing metallic materials. The procedures
included provided acceptable results for samples analyzed during interlaboratory testing. The investigator shall determine the
appropriateness of listed procedures.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 State all numerical values in terms of SI units unless specific instrumentation software reports surface area using alternate
units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report surface area
2 2
as m /g, instead of using correct SI units (m /kg).
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.
2. Referenced Documents
3
2.1 ASTM Standards:
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology B243 for additional terms specific to metal powders.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 adsorbate, n—material that has been retained by the process of adsorption.
3.2.2 adsorbent, n—any solid having the ability to concentrate or collect significant quantities of other substances on its surface.
3.2.3 adsorption, n—a process in which fluid molecules are concentrated or collected on a surface by chemical or physical
forces, or both.
3.2.4 adsorptive, n—any substance available for adsorption.
3.2.5 outgassing, n—the evolution of gas from a material in a vacuum or inert gas flow, at or above ambient temperature.
3.2.6 physical adsorption (van der Waals adsorption), n—the binding of an adsorbate to the surface of a solid by forces whose
energy levels approximate those of condensation.
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.03
on Refractory Metal Powders.
Current edition approved May 1, 2010Jan. 1, 2017. Published June 2010February 2017. Originally approved in 2002. Last previous edition approved in 20082010 as
B922–02(2008).B922–10. DOI: 10.1520/B0922-10.10.1520/B0922-17.
2
Brunauer, S., Emmett, P. H., and Teller, E. “Adsorption of Gases in Multimolecular Layers.” Journal of the American Chemical Society, Vol. 60, 1938, pp. 309-319.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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B922 − 17
3.2.7 surface area, n—the total area of the surface of a powder or solid including both external and accessible internal surfaces
(from voids, cracks, open porosity, and fissures). The area may be calculated by the BET (Brunauer, Emmett, and Teller) equation
from gas adsorption data obtained under specific conditions. It is useful to express this value as the specific surf
...
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