ASTM B923-02

Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry

SIGNIFICANCE AND USE
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 This method uses SI units as standard according to Practice E 380. State all numerical values in terms of SI units unless specific instrumentation software reports volume and/or density using alternate 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/m 3).
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.

General Information

• Status: Historical
• Publication Date: 09-Oct-2002
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.03 - Refractory Metal Powders

Relations

• Replaced By: ASTM B923-02(2008) - Standard Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry
• Effective Date: 01-Apr-2008
• Referred By: ASTM F3637-23 - Standard Guide for Additive Manufacturing of Metal — Finished Part Properties — Methods for Relative Density Measurement
• Effective Date: 10-Oct-2002
• Referred By: ASTM D8091-21 - Standard Guide for Impregnation of Graphite with Molten Salt
• Effective Date: 10-Oct-2002
• Referred By: ASTM F2989-21 - Standard Specification for Metal Injection Molded Unalloyed Titanium Components for Surgical Implant Applications
• Effective Date: 10-Oct-2002
• Referred By: ASTM D8325-20 - Standard Guide for Evaluation of Nuclear Graphite Surface Area and Porosity by Gas Adsorption Measurements
• Effective Date: 10-Oct-2002
• Referred By: ASTM B988-18(2022) - Standard Specification for Powder Metallurgy (PM) Titanium and Titanium Alloy Structural Components
• Effective Date: 10-Oct-2002
• Referred By: ASTM C750-18 - Standard Specification for Nuclear-Grade Boron Carbide Powder
• Effective Date: 10-Oct-2002
• Referred By: ASTM F2886-17(2023) - Standard Specification for Metal Injection Molded Cobalt-28Chromium-6Molybdenum Components for Surgical Implant Applications
• Effective Date: 10-Oct-2002
• Referred By: ASTM F3049-14(2021) - Standard Guide for Characterizing Properties of Metal Powders Used for Additive Manufacturing Processes
• Effective Date: 10-Oct-2002
• Referred By: ASTM F2885-17(2023) - Standard Specification for Metal Injection Molded Titanium-6Aluminum-4Vanadium Components for Surgical Implant Applications
• Effective Date: 10-Oct-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B923–02
Standard Test Method for
Metal Powder Skeletal Density by Helium or Nitrogen
Pycnometry
This standard is issued under the fixed designation B 923; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers determination of skeletal den- 3.1 Definitions—Refer to Terminology B 243 for additional
sity of metal powders. The test method specifies general definitions relating to metal powders.
procedures that are applicable to many commercial pycnom- 3.2 Definitions: Definitions of Terms Specific to This Stan-
etry instruments. The method provides specific sample outgas- dard:
sing procedures for listed materials. It includes additional 3.2.1 density, n—the mass per unit volume of a material.
general outgassing instructions for other metals. The ideal gas 3.2.2 density, skeletal, n—the ratio of mass of discrete
law forms the basis for all calculations. pieces of solid material to the sum of the volumes of the solid
1.2 This test method does not include all existing proce- material in the pieces and closed (or blind) pores within the
dures appropriate for outgassing metal materials. The included pieces.
procedures provided acceptable results for samples analyzed 3.2.3 outgassing, n—the evolution of gas from a material in
during an interlaboratory study. The investigator shall deter- a vacuum or inert gas flow, at or above ambient temperature.
mine the appropriateness of listed procedures. 3.2.4 skeletal volume, n—the sum of the volumes: the solid
1.3 This method uses SI units as standard according to material in the pieces and closed (or blind) pores within the
Practice E 380. State all numerical values in terms of SI units pieces.
unless specific instrumentation software reports volume and/or
4. Summary of Test Method
density using alternate units. In this case, present both reported
and equivalent SI units in the final written report. Many 4.1 An appropriately sized sample (to provide at least the
minimum skeletal volume required for reliable results for the
instruments report skeletal density as g/cm instead of using
instrument or apparatus used) is outgassed under appropriate
correct SI units (kg/m ).
1.4 This standard does not purport to address all of the conditions prior to analysis.
4.2 The sample is weighed to nearest 0.1 mg. It is important
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- to use an analytical balance to determine the sample mass. The
pycnometer measures the total displaced skeletal volume of the
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. sample under analysis. The sample mass is then used to
calculate the skeletal density of the metal. Any error in the
2. Referenced Documents
sample mass will affect the calculated density. Some cleaning
2.1 ASTM Standards: of the sample surface may take place inside the pycnometer.
B 215 Practices for Sampling Finished Lots of Metal Pow- Therefore, it is best to reweigh the sample after analysis and
ders use the final mass when calculating skeletal density.
B 243 Definitions of Terms Used in Powder Metallurgy 4.3 Sample skeletal volume is determined a minimum of
E 380 Practice for Use of the International System of Units five times. Skeletal volume average and standard deviation are
(SI) calculated using standard statistical methods.
E 691 Practice for Conducting an Interlaboratory Study to 4.4 Calculations are based on the ideal gas law, as required
Determine the Precision of a Test Method by the instrument being used for the determination. The
assumption of ideal behavior is accepted as valid at analytical
temperatures and pressures. For instruments designed with two
This test method is under the jurisdiction of ASTM Committee B09 on Metal
pressure chambers, one a sample compartment, and the other a
PowdersandMetalPowderProductandisthedirectresponsibilityofSubcommittee
gas expansion chamber, the equation for sample volume
B09.03 on Refractory Metal Powders.
calculation takes the form:
Current edition approved Oct. 10, 2002. Published December 2002.
Annual Book of ASTM Standards, Vol 02.05.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B923–02
P
8.2 Nitrogen, 99.999 mole percent, with the sum of O ,
V 5 V 2 V · (1)
S D
sample cell exp
P 2 P
1 2 argon, CO , hydrocarbons (as CH ), and H O totaling less than
2 4 2
10 parts per million; dry and oil-free; cylinder, or other source
where:
of purified nitrogen.
V = calculated sample volume,
sample
8.3 Other High Purity Gas, dry and oil-free; cylinder, or
V = calibrated sample compartment volume,
cell
other source of gas, if other gas is to be used as the analysis or
V = calibrated expansion volume,
exp
flushing gas.The actual composition of the gas shall be known.
P = measured gas pressure when only V is filled
1 cell
with analysis gas, and
9. Hazards
P = measured gas pressure after expansion of the
analysis gas into V .
exp 9.1 Precautions applying to the use of compressed gases
should be observed.
5. Significance and Use
5.1 Both suppliers and users of metals can benefit from
10. Sampling, Test Specimens, and Test Units
knowledge of the skeletal density of these materials. Results of
10.1 No specific instructions are given. However, it is
many intermediate and final processing steps are controlled by
important that the test portion being analyzed represent the
or related to skeletal density of the metal. In addition, the
larger bulk sample from which it is taken. The bulk sample
performance of many sintered or cast metal structures may be
should be homogenized before any sampling takes place. Best
predicted from the skeletal density of the starting metal
results are obtained when a flowing bulk material is tempo-
powder, for all or a portion of the finished piece.
rarily diverted into a collector for an appropriate time. It is
6. Interferences better to sample the entire flow for a short time than to sample
a portion of the flow for a longer time. Collecting several small
6.1 This test method can be used to determine the skeletal
test portions and combining them improves the reliability of
volume of a powder or solid only after the open pores have
the sampling process. Rotating rifflers are available which
been emptied of any physically adsorbed molecules. Such
satisfy these requirements. Refer to Practices B 215 for infor-
adsorbed species (for example, water or volatile organic
mation on the use of a chute sample splitter.
compounds) prevent entry of the gas probe molecules into the
open porosity of the sample.
...