ASTM B821-23

Standard Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis

SIGNIFICANCE AND USE
4.1 The method of powder dispersion in a liquid has a significant effect on the results of a particle size distribution analysis. The analysis will show a too-coarse, unstable, or nonrepeatable distribution if the powder has not been dispersed adequately. It is therefore important that parties wishing to compare their analyses use the same dispersion technique.  
4.2 This guide provides ways of deriving dispersion techniques for a range of metal powders and compounds. It should be used by all parties performing liquid-dispersed particle size analysis of all of the materials covered by this guide (see 1.1, 1.2, and 4.1).  
4.3 Table 1 provides some dispersion procedures that have been found useful and consistent for the particular materials listed there. These are only suggested dispersion procedures; the procedures and dispersion checks of 7.1.2 – 7.1.4, or the more detailed method development procedures of Guide E3340, should still be used to verify adequate dispersion for each particular material and particle size range. (A) Stated ultrasonic power and duration times are given as an indication only. Specific conditions should be sought for the particular system in question during the method development phase.(B) Tween 21, chemically known as polyoxyethylene6 sorbitan monolaurate, is manufactured by Croda International PLC, and is available from various chemical suppliers.(C) Three to five drops Tween 21 in 30 to 50 mL water.  
4.4 This guide should be used in the preparation of powders for use in Test Methods B761 and B822 and other procedures that analyze metal powder particle size distributions in liquid-dispersed systems.
SCOPE
1.1 This guide covers the dispersion in liquids of metal powders and related compounds for subsequent use in particle size analysis instruments. This guide describes a general procedure for achieving and determining dispersion; it also lists procedures that have been found useful for certain materials.  
1.2 This guide does not include specific procedures for dry dispersion of particulate materials. It only indicates when liquid dispersion is not appropriate and dry dispersion must be utilized (see 7.1.2.1). For guidance on development of methods of dry dispersion, see Guide E3340.  
1.3 This guide is limited to metal powders and related metal compounds. However, the general procedure described herein may be used, with caution as to its significance, for other particulate materials, such as ceramics, pigments, minerals, etc.  
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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: 31-Jan-2023
• ICS: 19.120 - Particle size analysis. Sieving
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.02 - Base Metal Powders

Relations

• Refers: ASTM B243-18 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Oct-2018
• Refers: ASTM B243-16 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Jul-2016
• Refers: ASTM B243-13 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Nov-2013
• Refers: ASTM B243-12 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Jul-2012
• Refers: ASTM B243-11 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Nov-2011
• Refers: ASTM B761-06(2011) - Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity Sedimentation
• Effective Date: 01-Oct-2011
• Refers: ASTM B215-10 - Standard Practices for Sampling Metal Powders
• Effective Date: 01-Dec-2010
• Refers: ASTM B822-10 - Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering
• Effective Date: 01-May-2010
• Refers: ASTM B243-10 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Jan-2010
• Refers: ASTM B243-09a - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Dec-2009
• Refers: ASTM B243-09 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Jan-2009
• Refers: ASTM B215-08 - Standard Practices for Sampling Metal Powders
• Effective Date: 01-Nov-2008
• Refers: ASTM B243-08a - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Mar-2008
• Refers: ASTM B243-08 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Feb-2008
• Refers: ASTM B243-06 - Standard Terminology of Powder Metallurgy
• Effective Date: 01-Nov-2006

Overview

ASTM B821-23: Standard Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis provides a comprehensive framework for preparing metal powders and related compounds for liquid-dispersed particle size analysis. The method of dispersing powders in a liquid medium significantly affects the accuracy and reliability of particle size distribution results. This guide outlines general procedures, practical recommendations, and important considerations to ensure consistent sample preparation, supporting repeatable and meaningful analytical outcomes across different laboratories and processes.

Key Topics

• Significance of Proper Dispersion: Inadequate liquid dispersion of metal powders can lead to inaccurate particle size distributions, manifesting as too-coarse, unstable, or irreproducible measurement results. Using standardized dispersion techniques is essential for comparability and reliability in analysis.
• Scope and Applicability: This standard applies primarily to metal powders and related metal compounds but may, with caution, be extended to other particulate materials such as ceramics, pigments, and minerals.
• General Dispersion Procedure: The guide details each step-all the way from initial microscopic observation, correct selection of liquid carrier and surfactant, to dispersion techniques such as ultrasonic treatment and subsequent analytical checks for adequacy.
• Recommended Dispersion Methods: Suggestive procedures for dispersing specific metals and compounds (e.g., iron, copper, tungsten carbide) are included, though practitioners are encouraged to verify and optimize these for their unique material and process requirements.
• Apparatus and Reagents: Guidance is provided on suitable equipment-such as microscopes, ultrasonic probes, and baths-as well as on the use of reagent-grade chemicals and appropriate surfactants or stabilizers.

Applications

Particle size analysis of metal powders is critical within numerous industries, including additive manufacturing, powder metallurgy, chemicals, and advanced materials research. This standard ensures:

• Improved Sample Preparation: Adoption of ASTM B821-23 helps laboratories achieve uniform sample dispersion, which is key for accurate laser diffraction, light scattering, or sedimentation-based particle size measurements.
• Method Validation: By following a consistent framework, organizations can develop and validate in-house procedures that enhance reproducibility and facilitate audit readiness.
• Support for Quality Control: Reliable particle size analysis underpins essential quality control processes, affecting product performance attributes such as flowability, sintering behavior, and final material properties.
• Compatibility With Test Methods: This guide directly supports the preparation of samples for use in related analytical standards such as ASTM B761 (gravity sedimentation) and ASTM B822 (light scattering).
• Adaptable Approach: While primarily for metal powders, the principles outlined may also be applicable-with due consideration-to the dispersion and analysis of other particulate materials.

Related Standards

• ASTM B215 - Practices for Sampling Metal Powders: Provides standardized techniques for sampling to ensure representative testing.
• ASTM B243 - Terminology of Powder Metallurgy: Contains essential terminology and definitions for the field.
• ASTM B761 - Test Method for Particle Size Distribution of Metal Powders by Gravity Sedimentation: Applicable for particle size analysis using sedimentation methods.
• ASTM B822 - Test Method for Particle Size Distribution of Metal Powders by Light Scattering: Outlines procedures for laser diffraction and light scattering measurements.
• ASTM E3340 - Guide for Development of Laser Diffraction Particle Size Analysis Methods: Offers guidance on establishing detailed method development for laser diffraction techniques.

By integrating ASTM B821-23 into laboratory and industrial practices, professionals can ensure their particle size analyses of metal powders are accurate, reproducible, and in line with globally recognized standards, supporting both quality assurance and regulatory compliance efforts.

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: B821 − 23
Standard Guide for
Liquid Dispersion of Metal Powders and Related
Compounds for Particle Size Analysis
This standard is issued under the fixed designation B821; 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
1.1 This guide covers the dispersion in liquids of metal 2.1 ASTM Standards:
powders and related compounds for subsequent use in particle B215 Practices for Sampling Metal Powders
size analysis instruments. This guide describes a general B243 Terminology of Powder Metallurgy
procedure for achieving and determining dispersion; it also B761 Test Method for Particle Size Distribution of Metal
lists procedures that have been found useful for certain Powders and Related Compounds by X-Ray Monitoring
materials. of Gravity Sedimentation
B822 Test Method for Particle Size Distribution of Metal
1.2 This guide does not include specific procedures for dry
Powders and Related Compounds by Light Scattering
dispersion of particulate materials. It only indicates when
E3340 Guide for Development of Laser Diffraction Particle
liquid dispersion is not appropriate and dry dispersion must be
Size Analysis Methods for Powder Materials
utilized (see 7.1.2.1). For guidance on development of methods
of dry dispersion, see Guide E3340.
3. Terminology
1.3 This guide is limited to metal powders and related metal
3.1 Definitions—Definitions of powder metallurgy terms
compounds. However, the general procedure described herein
can be found in Terminology B243.
may be used, with caution as to its significance, for other
particulate materials, such as ceramics, pigments, minerals, etc.
4. Significance and Use
1.4 Units—The values stated in SI units are to be regarded 4.1 The method of powder dispersion in a liquid has a
as standard. No other units of measurement are included in this
significant effect on the results of a particle size distribution
standard.
analysis. The analysis will show a too-coarse, unstable, or
nonrepeatable distribution if the powder has not been dispersed
1.5 This standard does not purport to address all of the
adequately. It is therefore important that parties wishing to
safety concerns, if any, associated with its use. It is the
compare their analyses use the same dispersion technique.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.2 This guide provides ways of deriving dispersion tech-
mine the applicability of regulatory limitations prior to use.
niques for a range of metal powders and compounds. It should
1.6 This international standard was developed in accor-
be used by all parties performing liquid-dispersed particle size
dance with internationally recognized principles on standard-
analysis of all of the materials covered by this guide (see 1.1,
ization established in the Decision on Principles for the
1.2, and 4.1).
Development of International Standards, Guides and Recom-
4.3 Table 1 provides some dispersion procedures that have
mendations issued by the World Trade Organization Technical
been found useful and consistent for the particular materials
Barriers to Trade (TBT) Committee.
listed there. These are only suggested dispersion procedures;
the procedures and dispersion checks of 7.1.2 – 7.1.4, or the
more detailed method development procedures of Guide
This guide is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.02 on Base Metal Powders. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2023. Published February 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1992. Last previous edition approved 2022 as B821 – 22. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0821-23. 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
B821 − 23
TABLE 1 Useful Dispersion Procedures for Some Specific Materials
Ultrasonic
A
Treatment
Carrier Additive Surfactant or Additive
Material
Liquid Stabilizer Concentration
Power
Type Time, min
Level, W
Chromium carbide water none . none . .
or
bath 25 5
B C
Copper water Tween 21 3–5 drops bath 80 1
B
Ferroalloys isopropyl Tween 21 10 % bath 80 1
alcohol
B C
Iron/steel water Tween 21 3–5 drops bath 80 1
B C
Manganese sulfide water Tween 21 3–5 drops bath 80 1
Molybdenum water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
or
bath 25 5
B C
Nickel water Tween 21 3–5 drops bath 80 1
Tantalum water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
Tantalum carbide water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
or
bath 25 5
Tungsten (D # 20 μm) water sodium hexametaphosphate 0.01 % probe 160 3
or
(D > 20 μm, Run Dry) bath 80 10
or
bath 25 5
Tungsten carbide water sodium hexametaphosphate 0.01 % probe 160 3
(D # 20 μm) or
bath 80 10
(D > 20 μm, Run Dry) or
bath 25 5
A
Stated ultrasonic power and duration times are given as an indication only. Specific conditions should be sought for the particular system in question during the method
development phase.
B 6
Tween 21, chemically known as polyoxyethylene sorbitan monolaurate, is manufactured by Croda International PLC, and is available from various chemical suppliers.
C
Three to five drops Tween 21 in 30 to 50 mL water.
E3340, should still be used to verify adequate dispersion for Society. Other grades may be used, provided it is first
each particular material and particle size range. ascertained that the reagent is of sufficiently high purity to
permit its use without lessening the accuracy of the determi-
4.4 This guide should be used in the preparation of powders
nation.
for use in Test Methods B761 and B822 and other procedures
that analyze metal powder particle size distributions in liquid-
6.2 Surfactants/Stabilizers—Some suggested surfactants or
dispersed systems.
stabilizers are listed in Table 1 and in the references of
4,5,6
Footnotes 4 through 6.
5. Apparatus
5.1 Microscope, suitable for observation of particles in the
size range of 5 to 1000 μm.
5.2 Ultrasonic Probe, 12.7 mm tip, with the power level to
be determined by this guide.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
5.3 Ultrasonic Bath—Power level to be determined by this Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical
guide.
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
6. Reagents
copeial Convention, Inc. (USPC), Rockville, MD.
Allen, T., Particle Size Measurement, 4th Edition, Chapman and Hall, London,
6.1 Purity of Reagents—Reagent grade chemicals should be
UK, 1991.
used in all tests. Unless otherwise indicated, it is intended that
Nelson, R. D., Dispersing Powders in Liquids, Elsevier, New York, NY, 1988.
all reagents should conform to the specifications of the
SediGraph III 5120 Operator’s Manual, Micromeritics Corporation, Norcross,
Committee on Analytical Reagents of the American Chemical GA, 1998, pp. C-3, C-4, and H-3.
B821
...

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: B821 − 22 B821 − 23
Standard Guide for
Liquid Dispersion of Metal Powders and Related
Compounds for Particle Size Analysis
This standard is issued under the fixed designation B821; 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 guide covers the dispersion in liquids of metal powders and related compounds for subsequent use in particle size analysis
instruments. This guide describes a general procedure for achieving and determining dispersion; it also lists procedures that have
been found useful for certain materials.
1.2 This guide does not include specific procedures for dry dispersion of particulate materials. It only indicates when liquid
dispersion is not appropriate and dry dispersion must be utilized (see 7.1.2.1). For guidance on development of methods of dry
dispersion, see Guide E3340.
1.3 This guide is limited to metal powders and related metal compounds. However, the general procedure described herein may
be used, with caution as to its significance, for other particulate materials, such as ceramics, pigments, minerals, etc.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 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.
1.6 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
2.1 ASTM Standards:
B215 Practices for Sampling Metal Powders
B243 Terminology of Powder Metallurgy
B761 Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity
Sedimentation
B822 Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering
E3340 Guide for Development of Laser Diffraction Particle Size Analysis Methods for Powder Materials
This guide is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.02
on Base Metal Powders.
Current edition approved Nov. 1, 2022Feb. 1, 2023. Published December 2022February 2023. Originally approved in 1992. Last previous edition approved 20162022 as
B821 – 10B821 – 22.(2016). DOI: 10.1520/B0821-22.10.1520/B0821-23.
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
B821 − 23
3. Terminology
3.1 Definitions—Definitions of powder metallurgy terms can be found in Terminology B243.
4. Significance and Use
4.1 The method of powder dispersion in a liquid has a significant effect on the results of a particle size distribution analysis. The
analysis will show a too-coarse, unstable, or nonrepeatable distribution if the powder has not been dispersed adequately. It is
therefore important that parties wishing to compare their analyses use the same dispersion technique.
4.2 This guide provides ways of deriving dispersion techniques for a range of metal powders and compounds. It should be used
by all parties performing liquid-dispersed particle size analysis of all of the materials covered by this guide (see 1.1, 1.2, and 4.1).
4.3 Table 1 provides some dispersion procedures that have been found useful and consistent for the particular materials listed
there. These are only suggested dispersion procedures; the procedures and dispersion checks of 7.1.2 – 7.1.4, or the more detailed
method development procedures of Guide E3340, should still be used to verify adequate dispersion for each particular material
and particle size range.
TABLE 1 Useful Dispersion Procedures for Some Specific Materials
Ultrasonic
A
Treatment
Carrier Additive Surfactant or Additive
Material
Liquid Stabilizer Concentration
Power
Type Time, min
Level, W
Chromium carbide water none . none . .
or
bath 25 5
B C
Copper water Tween 21 3–5 drops bath 80 1
B
Ferroalloys isopropyl Tween 21 10 % bath 80 1
alcohol
B C
Iron/steel water Tween 21 3–5 drops bath 80 1
B C
Manganese sulfide water Tween 21 3–5 drops bath 80 1
Molybdenum water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
or
bath 25 5
B C
Nickel water Tween 21 3–5 drops bath 80 1
Tantalum water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
Tantalum carbide water sodium hexametaphosphate 0.01 % probe 160 3
or
bath 80 10
or
bath 25 5
Tungsten (D # 20 μm) water sodium hexametaphosphate 0.01 % probe 160 3
or
(D > 20 μm, Run Dry) bath 80 10
or
bath 25 5
Tungsten (D # 20 μm) water sodium hexametaphosphate 0.01 % probe 160 3
or
(D > 20 μm, Run Dry) bath 80 10
or
bath 25 5
Tungsten carbide water sodium hexametaphosphate 0.01 % probe 160 3
(D # 20 μm) or
bath 80 10
(D > 20 μm, Run Dry) or
bath 25 5
Tungsten carbide water sodium hexametaphosphate 0.01 % probe 160 3
(D # 20 μm) or
bath 80 10
(D > 20 μm, Run Dry) or
bath 25 5
A
Stated ultrasonic power and duration times are given as an indication only. Specific conditions should be sought for the particular system in question during the method
development phase.
B 6
Tween 21, chemically known as polyoxyethylene sorbitan monolaurate, is manufactured by Croda International PLC, and is available from various chemical suppliers.
C
Three to five drops Tween 21 in 30 to 50 mL water.
B821 − 23
4.4 This guide should be used in the preparation of powders for use in Test Methods B761 and B822 and other procedures that
analyze metal powder particle size distributions in liquid-dispersed systems.
5. Apparatus
5.1 Microscope, suitable for observation of particles in the size range of 5 to 1000 μm.
5.2 Ultrasonic Probe, 12.7 mm tip, with the power level to be determined by this guide.
5.3 Ultrasonic Bath—Power level to be determined by this guide.
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals should be used in all tests. Unless otherwise indicated, it is intended that all
reagents should conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society. Other
grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening
the accuracy of the determination.
6.2 Surfactants/Stabilizers—Some suggested surfactants or stabilizers are listed in Table 1 and in the references of Footnotes 4
4,5,6
through 6.
FIG. 1 General Dispersion Procedure
Reagent Chemicals, American Chemical Society SpecificationsACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
Allen, T., Particle Size Measurement, 4th Edition, Chapman and Hal
...