ASTM B922-22

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 Units—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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 28-Feb-2022
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.03 - Refractory Metal Powders

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:B922 −22
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* 2. Referenced Documents
3
1.1 This test method covers determination of surface area of 2.1 ASTM Standards:
metal powders. The test method specifies general procedures B215 Practices for Sampling Metal Powders
that are applicable to many commercial physical adsorption B243 Terminology of Powder Metallurgy
instruments. The method provides specific sample outgassing E177 Practice for Use of the Terms Precision and Bias in
procedures for listed materials. It includes additional general ASTM Test Methods
outgassing instructions for other metals. The multipoint equa- E691 Practice for Conducting an Interlaboratory Study to
2
tion of Brunauer, Emmett, and Teller (BET), along with the Determine the Precision of a Test Method
single point approximation of the BET equation, forms the
3. Terminology
basis for all calculations.
3.1 Definitions—Refer to Terminology B243 for additional
1.2 This test method does not include all existing proce-
terms specific to metal powders.
dures appropriate for outgassing metallic materials. The pro-
cedures included provided acceptable results for samples 3.2 Definitions of Terms Specific to This Standard:
analyzed during interlaboratory testing. The investigator shall
3.2.1 adsorbate, n—material that has been retained by the
determine the appropriateness of listed procedures. process of adsorption.
1.3 Units—The values stated in SI units are to be regarded 3.2.2 adsorbent, n—any solid having the ability to concen-
trate or collect significant quantities of other substances on its
as standard. No other units of measurement are included in this
standard. surface.
1.3.1 State all numerical values in terms of SI units, unless
3.2.3 adsorption, n—a process in which fluid molecules are
specific instrumentation software reports surface area using
concentrated or collected on a surface by chemical or physical
alternate units. In this case, present both reported and equiva-
forces, or both.
lentSIunitsinthefinalwrittenreport.Manyinstrumentsreport
3.2.4 adsorptive, n—any substance available for adsorption.
2 2
surface area as m /g, instead of using correct SI units (m /kg).
3.2.5 outgassing, n—the evolution of gas from a material in
1.4 This standard does not purport to address all of the
a vacuum or inert gas flow, at or above ambient temperature.
safety concerns, if any, associated with its use. It is the
3.2.6 physical adsorption (van der Waals adsorption),
responsibility of the user of this standard to establish appro-
n—the binding of an adsorbate to the surface of a solid by
priate safety, health, and environmental practices and deter-
forces whose energy levels approximate those of condensation.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 3.2.7 surface area, n—the total area of the surface of a
dance with internationally recognized principles on standard- powderorsolid,includingbothexternalandaccessibleinternal
ization established in the Decision on Principles for the surfaces (from voids, cracks, open porosity, and fissures).
Development of International Standards, Guides and Recom- 3.2.7.1 Discussion—The area may be calculated by the BET
mendations issued by the World Trade Organization Technical (Brunauer, Emmett, and Teller) equation from gas adsorption
Barriers to Trade (TBT) Committee. data obtained under specific conditions. It is useful to express
thisvalueasthespecificsurfacearea,forexample,surfacearea
2
per unit mass of sample (m /kg).
1
This test method is under the jurisdiction of ASTM Committee B09 on Metal
3.2.8 surface area (BET), n—the total surface area of a solid
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.03 on Refractory Metal Powders. calculated by the BET (Brunauer, Emmett, Teller) equation,
Current edition approved March 1, 2022. Published March 2022. Originally
approved in 2002. Last previous edition approved in 2020 as B922 – 20. DOI:
3
10.1520/B0922-22. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
2
Brunauer, S., Emmett, P. H., and Teller, E. “Adsorption of Gases in Multimo- contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
le
...

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 − 20 B922 − 22
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 Units—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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
3
2.1 ASTM Standards:
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
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, 2020March 1, 2022. Published May 2020March 2022. Originally approved in 2002. Last previous edition approved in 20172020 as
B922 – 17.B922 – 20. DOI: 10.1520/B0922-20.10.1520/B0922-22.
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 [e-mail]. 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

---------------------- Page: 1 ----------------------
B922 − 22
3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology B243 for additional terms specific to metal powders.
3.1 Definitions—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 a
...