ASTM B923-16
(Test Method)Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry
Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry
SIGNIFICANCE AND USE
5.1 Both suppliers and users of metals can benefit from knowledge of the skeletal density of these materials. Results of many intermediate and final processing steps are controlled by or related to skeletal density of the metal. In addition, the performance of many sintered or cast metal structures may be predicted from the skeletal density of the starting metal powder, for all or a portion of the finished piece.
SCOPE
1.1 This test method covers determination of skeletal density of metal powders. The test method specifies general procedures that are applicable to many commercial pycnometry instruments. The method provides specific sample outgassing procedures for listed materials. It includes additional general outgassing instructions for other metals. The ideal gas law forms the basis for all calculations.
1.2 This test method does not include all existing procedures appropriate for outgassing metal materials. The included procedures provided acceptable results for samples analyzed during an interlaboratory study. 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 volume or density, or both, using alternative units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report skeletal density as g/cm3 instead of using correct SI units (kg/m3).
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: B923 − 16
Standard Test Method for
Metal Powder Skeletal Density by Helium or Nitrogen
1
Pycnometry
This standard is issued under the fixed designation B923; 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* E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method covers determination of skeletal den-
sity of metal powders. The test method specifies general
3. Terminology
procedures that are applicable to many commercial pycnom-
3.1 Definitions:
etry instruments. The method provides specific sample outgas-
3.1.1 Refer to Terminology B243 for additional definitions
sing procedures for listed materials. It includes additional
relating to metal powders.
general outgassing instructions for other metals. The ideal gas
3.2 Definitions of Terms Specific to This Standard:
law forms the basis for all calculations.
3.2.1 density, n—the mass per unit volume of a material.
1.2 This test method does not include all existing proce-
3.2.2 density, skeletal, n—the ratio of mass of discrete
dures appropriate for outgassing metal materials. The included
pieces of solid material to the sum of the volumes of the solid
procedures provided acceptable results for samples analyzed
material in the pieces and closed pores within the pieces.
during an interlaboratory study. The investigator shall deter-
3.2.3 outgassing, n—the evolution of gas from a material in
mine the appropriateness of listed procedures.
a vacuum or inert gas flow, at or above ambient temperature.
1.3 The values stated in SI units are to be regarded as
3.2.4 skeletal volume, n—the sum of the volumes: the solid
standard. No other units of measurement are included in this
material in the pieces and closed pores within the pieces.
standard.
1.3.1 State all numerical values in terms of SI units unless
4. Summary of Test Method
specific instrumentation software reports volume or density, or
4.1 An appropriately sized sample (to provide at least the
both, using alternative units. In this case, present both reported
minimum skeletal volume required for reliable results for the
and equivalent SI units in the final written report. Many
3
instrument or apparatus used) is outgassed under appropriate
instruments report skeletal density as g/cm instead of using
3
conditions prior to analysis.
correct SI units (kg/m ).
1.4 This standard does not purport to address all of the 4.2 The sample is weighed to nearest 0.1 mg. It is important
to use an analytical balance to determine the sample mass. The
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- pycnometer measures the total displaced skeletal volume of the
sample under analysis. The sample mass is then used to
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. calculate the skeletal density of the metal. Any error in the
sample mass will affect the calculated density. Some cleaning
2. Referenced Documents
of the sample surface may take place inside the pycnometer.
2
Therefore, it is best to reweigh the sample after analysis and
2.1 ASTM Standards:
use the final mass when calculating skeletal density.
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy
4.3 Sample skeletal volume is determined a minimum of
five times. Skeletal volume average and standard deviation are
calculated using standard statistical methods.
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 Subcom-
4.4 Calculations are based on the ideal gas law, as required
mittee B09.03 on Refractory Metal Powders.
by the instrument being used for the determination. The
Current edition approved Oct. 1, 2016. Published October 2016. Originally
assumption of ideal behavior is accepted as valid at analytical
approved in 2002. Last previous edition approved in 2010 as B923–10. DOI:
10.1520/B0923-16.
temperatures and pressures. For instruments designed with two
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
pressure chambers, one a sample compartment, and the other a
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
gas expansion chamber, the equation for sample volume
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. calculation takes the form:
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 B
...
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: B923 − 10 B923 − 16
Standard Test Method for
Metal Powder Skeletal Density by Helium or Nitrogen
1
Pycnometry
This standard is issued under the fixed designation B923; 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 skeletal density of metal powders. The test method specifies general procedures
that are applicable to many commercial pycnometry instruments. The method provides specific sample outgassing procedures for
listed materials. It includes additional general outgassing instructions for other metals. The ideal gas law forms the basis for all
calculations.
1.2 This test method does not include all existing procedures appropriate for outgassing metal materials. The included
procedures provided acceptable results for samples analyzed during an interlaboratory study. 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 This test method uses SI units as standard in accordance with IEEE/ASTM SI 10. State all numerical values in terms of
SI units unless specific instrumentation software reports volume and/or density using alternateor density, or both, using alternative
units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report skeletal density
3 3
as g/cm instead of using correct SI units (kg/m ).
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
2
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
IEEE/ASTM SI 10 American National Standard for Metric Practice
3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology B243 for additional definitions relating to metal powders.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 density, n—the mass per unit volume of a material.
3.2.2 density, skeletal, n—the ratio of mass of discrete pieces of solid material to the sum of the volumes of the solid material
in the pieces and closed (or blind) pores within the pieces.
3.2.3 outgassing, n—the evolution of gas from a material in a vacuum or inert gas flow, at or above ambient temperature.
3.2.4 skeletal volume, n—the sum of the volumes: the solid material in the pieces and closed (or blind) pores within the pieces.
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, 2010Oct. 1, 2016. Published June 2010October 2016. Originally approved in 2002. Last previous edition approved in 20082010 as
B923–02(2008).B923–10. DOI: 10.1520/B0923-10.10.1520/B0923-16.
2
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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B923 − 16
4. Summary of Test Method
4.1 An appropriately sized sample (to provide at least the minimum skeletal volume required for reliable results for the
instrument or apparatus used) is outgassed under appropriate conditions prior to analysis.
4.2 The sample is weighed to nearest 0.1 mg. It is important to use an analytical balance to determine the sample mass. The
pycnometer measures the total displaced skeletal volume of the sample under analysis. The sample mass is then used to calculate
the skeletal density of the metal. Any error in the sample mass will affect the calculated density. Some cleaning of the sample
surface may take place inside the pycnom
...
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