ASTM B859-21

Standard Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size Analysis

SIGNIFICANCE AND USE
4.1 Refractory metal powders, such as tungsten and molybdenum, are usually produced by hydrogen reduction at high temperatures. Thus, they usually contain numerous large, strongly-sintered agglomerates. Many of the manufacturing processes using these powders involve a milling step or some similar treatment or depend on the individual particulate size, not on the agglomerate size.3 Thus, a knowledge of the individual particulate size distribution, not the agglomerate size distribution, is usually desired from a particle size analysis of these powders. This practice provides a procedure for breaking down agglomerates into their constituent particles (de-agglomeration), without excessive fracture of the individual particles. The procedure is often referred to as laboratory milling or rod milling.  
4.2 The laboratory milling conditions specified in this guide have been in use since 1965, initially as part of a particle size analysis test method. This guide was first published as a separate, stand-alone standard in 1995 because of its applicability in preparing powder samples for analysis by other methods as well (for example, Test Methods B761 and B822). Information on the development and establishment of the milling conditions here specified can be found in the footnoted reference.4  
4.3 The milling procedure described in this practice does not necessarily break down only agglomerates without fracturing individual particles; some particle fracture may occur in certain powders. However, use of this practice does  provide consistent particle size analysis results that have been found to relate well to powder behavior in numerous manufacturing processes.  
4.4 This practice shall be used for the de-agglomeration of the refractory metal powders and compounds listed in 1.2, when an evaluation of the individual particulate size distribution is required from the subsequent particle size analysis. It shall not be used when the agglomerate (as-is or as-supplied) size distr...
SCOPE
1.1 This practice covers the de-agglomeration of refractory metal powders and their compounds in preparation for particle size analysis.  
1.2 Experience has shown that this practice is satisfactory for the de-agglomeration of elemental tungsten, molybdenum, rhenium, and tantalum metal powders, and tungsten carbide. Other metal powders (for example, elemental metals, carbides, and nitrides) may be prepared for particle size analysis using this practice with caution as to effectiveness until actual satisfactory experience is developed.  
1.3 Units—With the exception of the values for mass, for which the use of the gram (g) unit is the long-standing industry practice, the values stated in SI units are to be regarded as standard. No other units of measure are included in this standard.  
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. For specific precautionary statements, see Note 2.  
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: 31-Mar-2021
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.03 - Refractory 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 B330-12 - Standard Test Methods for Estimating Average Particle Size of Metal Powders and Related Compounds Using Air Permeability
• Effective Date: 01-Nov-2012
• 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 B821-10 - Standard Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis
• Effective Date: 01-Sep-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 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 B821-02(2007) - Standard Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis
• Effective Date: 01-Oct-2007

Overview

ASTM B859-21, titled Standard Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size Analysis, provides a standardized procedure for preparing refractory metal powders-such as tungsten, molybdenum, rhenium, tantalum, and tungsten carbide-for accurate particle size analysis. Since these powders are commonly produced through high-temperature hydrogen reduction, they tend to contain large, strongly sintered agglomerates. Understanding the true particle size distribution is critical for powder metallurgy and related manufacturing processes.

By following the practices outlined in ASTM B859-21, laboratories and manufacturers can consistently break down agglomerates into individual constituent particles (de-agglomeration), minimizing excessive particle fracture and supporting precise particle size measurement required for process control and quality assurance.

Key Topics

• Refractory Metal Powders: Focuses on powders such as tungsten, molybdenum, rhenium, tantalum, and tungsten carbide, which are widely used in high-performance applications.
• De-Agglomeration Process: Specifies laboratory milling (often rod milling) as the preferred method for breaking agglomerates without significant destruction of individual particles.
• Sample Preparation: Establishes guidance on preparing samples for various particle size analysis techniques, ensuring uniformity and reproducibility.
• Consistency in Analysis: Emphasizes that particle size analysis after de-agglomeration provides results that correlate well with material behavior in manufacturing.
• Scope of Use: The method is intended for instances where knowledge of individual particle size distribution is required-not when agglomerate sizing is necessary.

Applications

Compliance with ASTM B859-21 is essential across several areas in powder metallurgy and materials science:

• Quality Control in Powder Production: Ensures that manufacturers can reliably measure the fine particle size distributions crucial for optimizing sintering, compaction, and other downstream processes.
• Research and Development: Supports repeatable and consistent measurements, essential for comparing new powder formulations or improvements in production techniques.
• Preparation for Particle Size Analysis: Used as a preparatory step before conducting analyses with standardized methods such as ASTM B761 (gravity sedimentation) and ASTM B822 (light scattering), as well as air permeability testing.
• Manufacturing of High-Performance Parts: Accurate particle size data guides the production of components requiring exceptional strength, density, and performance-common in aerospace, electronics, and hard metal tooling industries.

Related Standards

Several ASTM standards are referenced or commonly used in conjunction with ASTM B859-21 to ensure optimal results in powder preparation and particle size analysis:

• ASTM B243 - Terminology of Powder Metallurgy
• ASTM B330 - Test Methods for Estimating Average Particle Size of Metal Powders Using Air Permeability
• ASTM B761 - Test Method for Particle Size Distribution of Metal Powders by X-Ray Monitoring of Gravity Sedimentation
• ASTM B821 - Guide for Liquid Dispersion of Metal Powders for Particle Size Analysis
• ASTM B822 - Test Method for Particle Size Distribution by Light Scattering

Employing ASTM B859-21 in combination with these standards supports a comprehensive approach to refractory metal powder analysis, contributing to improved product quality, process consistency, and industry compliance.

Keywords: ASTM B859-21, de-agglomeration, refractory metal powders, particle size analysis, tungsten powder, molybdenum powder, laboratory milling, rod milling, powder metallurgy, standards compliance.

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: B859 − 21
Standard Practice for
De-Agglomeration of Refractory Metal Powders and Their
Compounds Prior to Particle Size Analysis
This standard is issued under the fixed designation B859; 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* B330 Test Methods for Estimating Average Particle Size of
Metal Powders and Related Compounds Using Air Per-
1.1 This practice covers the de-agglomeration of refractory
meability
metal powders and their compounds in preparation for particle
B761 Test Method for Particle Size Distribution of Metal
size analysis.
Powders and Related Compounds by X-Ray Monitoring
1.2 Experience has shown that this practice is satisfactory
of Gravity Sedimentation
for the de-agglomeration of elemental tungsten, molybdenum,
B821 Guide for Liquid Dispersion of Metal Powders and
rhenium, and tantalum metal powders, and tungsten carbide.
Related Compounds for Particle Size Analysis
Other metal powders (for example, elemental metals, carbides,
B822 Test Method for Particle Size Distribution of Metal
and nitrides) may be prepared for particle size analysis using
Powders and Related Compounds by Light Scattering
this practice with caution as to effectiveness until actual
satisfactory experience is developed.
3. Terminology
1.3 Units—With the exception of the values for mass, for
3.1 Definitions—Definitions of powder metallurgy terms
which the use of the gram (g) unit is the long-standing industry
can be found in Terminology B243.
practice, the values stated in SI units are to be regarded as
standard. No other units of measure are included in this
4. Significance and Use
standard.
4.1 Refractory metal powders, such as tungsten and
1.4 This standard does not purport to address all of the
molybdenum, are usually produced by hydrogen reduction at
safety concerns, if any, associated with its use. It is the
high temperatures. Thus, they usually contain numerous large,
responsibility of the user of this standard to establish appro-
strongly-sintered agglomerates. Many of the manufacturing
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. processes using these powders involve a milling step or some
For specific precautionary statements, see Note 2. similar treatment or depend on the individual particulate size,
1.5 This international standard was developed in accor- not on the agglomerate size. Thus, a knowledge of the
dance with internationally recognized principles on standard- individual particulate size distribution, not the agglomerate
ization established in the Decision on Principles for the
size distribution, is usually desired from a particle size analysis
Development of International Standards, Guides and Recom- of these powders. This practice provides a procedure for
mendations issued by the World Trade Organization Technical
breaking down agglomerates into their constituent particles
Barriers to Trade (TBT) Committee.
(de-agglomeration), without excessive fracture of the indi-
vidual particles. The procedure is often referred to as labora-
2. Referenced Documents
tory milling or rod milling.
2.1 ASTM Standards:
4.2 The laboratory milling conditions specified in this guide
B243 Terminology of Powder Metallurgy
have been in use since 1965, initially as part of a particle size
analysis test method. This guide was first published as a
This practice is under the jurisdiction of ASTM Committee B09 on Metal
separate, stand-alone standard in 1995 because of its applica-
Powders and Metal Powder Products and is the direct responsibility of Subcom-
bility in preparing powder samples for analysis by other
mittee B09.03 on Refractory Metal Powders.
methods as well (for example, Test Methods B761 and B822).
Current edition approved April 1, 2021. Published May 2021. Originally
approvedin1995.Lastpreviouseditionapprovedin2018asB859–13(2018).DOI:
10.1520/B0859-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Michaels, A. I., “Turbidimetric Particle Size Distribution Theory: Application
Standards volume information, refer to the standard’s Document Summary page on to Refractory Metal and Oxide Powders,” 1958 Symposium on Particle Size
the ASTM website. Measurement, ASTM STP 234, ASTM, 1959, pp. 207–244.
*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
B859 − 21
Information on the development and establishment of the 6. Procedure
milling conditions here specified can be found in the footnoted
6.1 Place 30 6 0.1 g of tungsten, molybdenum, rhenium, or
reference.
tantalummetal,or50 60.1goftungstencarbidepowderinthe
4.3 The milling procedure described in this practice does milling bottle containing the 50 tungsten milling rods.
not necessarily break down only agglomerates without fractur-
6.2 Seal the milling bottle and rotate on the jar roll mill for
ing individual particles; some particle fracture may occur in
60 min 6 15 s at a bottle speed of 145 6 5 rpm.After the first
certain powders. However, use of this practice does provide
5 min, check to be sure the rod
...

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: B859 − 13 (Reapproved 2018) B859 − 21
Standard Practice for
De-Agglomeration of Refractory Metal Powders and Their
Compounds Prior to Particle Size Analysis
This standard is issued under the fixed designation B859; 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 practice covers the de-agglomeration of refractory metal powders and their compounds in preparation for particle size
analysis.
1.2 Experience has shown that this practice is satisfactory for the de-agglomeration of elemental tungsten, molybdenum, rhenium,
and tantalum metal powders, and tungsten carbide. Other metal powders (for example, elemental metals, carbides, and nitrides)
may be prepared for particle size analysis using this practice with caution as to effectiveness until actual satisfactory experience
is developed.
1.3 Units—With the exception of the values for mass, for which the use of the gram (g) unit is the long-standing industry practice,
the values stated in SI units are to be regarded as standard. No other units of measure are included in this standard.
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. For specific precautionary statements, see Note 2.
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
2.1 ASTM Standards:
B243 Terminology of Powder Metallurgy
B330 Test Methods for Estimating Average Particle Size of Metal Powders and Related Compounds Using Air Permeability
B761 Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity
Sedimentation
B821 Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis
B822 Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering
2.2 ASTM Adjunct:
ADJB0859 Detailed Drawings of Alternative Steel Milling Bottles
This practice 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 April 1, 2018April 1, 2021. Published May 2018May 2021. Originally approved in 1995. Last previous edition approved in 20032018 as B859
– 13.13(2018). DOI: 10.1520/B0859-13R18.10.1520/B0859-21.
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
B859 − 21
3. Terminology
3.1 Definitions—Definitions of powder metallurgy terms can be found in Terminology B243.
4. Significance and Use
4.1 Refractory metal powders, such as tungsten and molybdenum, are usually produced by hydrogen reduction at high
temperatures. Thus, they usually contain numerous large, strongly-sintered agglomerates. Many of the manufacturing processes
using these powders involve a milling step or some similar treatment or depend on the individual particulate size, not on the
agglomerate size. Thus, a knowledge of the individual particulate size distribution, not the agglomerate size distribution, is usually
desired from a particle size analysis of these powders. This practice provides a procedure for breaking down agglomerates into their
constituent particles (de-agglomeration), without excessive fracture of the individual particles. The procedure is often referred to
as laboratory milling or rod milling.
4.2 The laboratory milling conditions specified in this guide have been in use since 1965, initially as part of a particle size analysis
test method. This guide was first published as a separate, stand-alone standard in 1995 because of its applicability in preparing
powder samples for analysis by other methods as well (for example, Test Methods B761 and B822). Information on the
development and establishment of the milling conditions here specified can be found in the footnoted reference.
4.3 The milling procedure described in this practice does not necessarily break down only agglomerates without fracturing
individual particles; some particle fracture may occur in certain powders. However, use of this practice does provide consistent
particle size analysis results that have been found to relate well to powder behavior in numerous manufacturing processes.
4.4 This practice shall be used for the de-agglomeration of the refractory metal powders and compounds listed in 1.2, when an
evaluation of the individual particulate size distribution is required from the subsequent particle size analysis. It shall not be used
when the agglomerate (as-is or as-supplied) size distribution is desired.
4.5 This practice may be used in preparing samples for Test Methods B330, B761, B822, and other particle size analysis methods,
prior to the dispers
...