ASTM B761-17(2021)
(Test Method)Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity Sedimentation
Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity Sedimentation
SIGNIFICANCE AND USE
4.1 This test method is useful to both producers and purchasers of powders, as outlined in 1.1 and 1.2, in determining particle size distribution for product specifications, manufacturing control, development, and research.
4.2 Users should be aware that sample concentrations used in this test method may not be what is considered ideal by some authorities, and that the range of this test method extends into the region where Brownian movement could be a factor in conventional sedimentation. Within the range of this test method, neither the sample concentration nor Brownian movement are believed to be significant.
4.3 Reported particle size measurement is a function of both the actual particle dimension and shape factor as well as the particular physical or chemical properties being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect reported particle size results.
SCOPE
1.1 This test method covers the determination of particle size distributions of metal powders. Experience has shown that this test method is satisfactory for the analysis of elemental tungsten, tungsten carbide, molybdenum, and tantalum powders, all with an as-supplied estimated average particle size of 6 μm or less, as determined by Test Method B330. Other metal powders (for example, elemental metals, carbides, and nitrides) may be analyzed using this test method with caution as to significance until actual satisfactory experience is developed (see 7.2). The procedure covers the determination of particle size distribution of the powder in the following two conditions:
1.1.1 As the powder is supplied (as-supplied), and
1.1.2 After the powder has been deagglomerated by rod milling as described in Practice B859.
1.2 This test method is applicable to particles of uniform density and composition having a particle size distribution range of 0.1 up to 100 μm.
1.2.1 However, the relationship between size and sedimentation velocity used in this test method assumes that particles sediment within the laminar flow regime. This requires that the particles sediment with a Reynolds number of 0.3 or less. Particle size distribution analysis for particles settling with a larger Reynolds number may be incorrect due to turbulent flow. Some materials covered by this test method may settle with Reynolds number greater than 0.3 if particles greater than 25 μm are present. The user of this test method should calculate the Reynolds number of the largest particle expected to be present in order to judge the quality of obtained results. Reynolds number (Re) can be calculated using the flowing equation
where
D = the diameter of the largest particle expected to be present, ρ = the particle density, ρ0 = the suspending liquid density, g = the acceleration due to gravity, and η = is the suspending liquid viscosity.
A table of the largest particles that can be analyzed with Reynolds number of 0.3 or less in water at 35°C is given for a number of metals in Table 1. A column of the Reynolds number calculated for a 30–μm particle sedimenting in the same liquid system is given for each material also.
1.3 Units—With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the longstanding industry practice, the values in SI units are to be regarded as 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. Specific hazard information is given in Section 7.
1.5 ...
General Information
- Status
- Published
- Publication Date
- 31-Aug-2021
- Technical Committee
- B09 - Metal Powders and Metal Powder Products
- Drafting Committee
- B09.03 - Refractory Metal Powders
Relations
- Effective Date
- 01-Apr-2022
- Effective Date
- 01-Oct-2017
- Effective Date
- 01-Oct-2017
- Effective Date
- 15-Nov-2013
- Effective Date
- 15-Nov-2013
- Effective Date
- 15-Nov-2013
- Effective Date
- 15-Nov-2013
- Effective Date
- 01-Oct-2013
- Effective Date
- 15-Aug-2013
- Effective Date
- 01-May-2013
- Effective Date
- 01-Nov-2012
- Effective Date
- 01-May-2012
- Effective Date
- 01-May-2012
- Effective Date
- 01-Nov-2011
- Effective Date
- 01-Sep-2010
Overview
ASTM B761-17(2021), titled "Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity Sedimentation," is an internationally recognized standard published by ASTM International. This document specifies a reliable method for determining the particle size distribution of metal powders and related compounds through the use of X-ray monitoring during the sedimentation process under controlled gravity. The standard is a key reference for both producers and purchasers of metal powders, supporting quality control, manufacturing, product specification, and research and development.
The test method is particularly established for elemental tungsten, tungsten carbide, molybdenum, and tantalum powders with an average particle size of 6 μm or less, but may also be applied to other metal powders, carbides, and nitrides under certain conditions and with appropriate caution.
Key Topics
- Particle Size Distribution: The standard details procedures for determining the particle size distributions in metal powders, both in their as-supplied form and after deagglomeration using rod milling per ASTM Practice B859.
- X-Ray Sedimentation Analysis: Utilizes X-ray extinction to monitor sedimentation, providing precise and reproducible particle size data for particle ranges from 0.1 μm to 100 μm.
- Sample Preparation: Emphasizes sample acquisition, handling, and the importance of sample deagglomeration for accurate size measurement.
- Applicability and Limitations:
- Designed for particles with uniform density and composition.
- The sedimentation process must remain in the laminar flow regime, typically requiring particles to have a Reynolds number of 0.3 or less.
- Larger particles or those outside the prescribed conditions may result in analysis inaccuracies due to turbulent flow.
- Precision and Reporting: The method references interlaboratory studies for repeatability and reproducibility and calls for careful statistical data reporting, including graphical or tabular representation.
Applications
The ASTM B761-17(2021) test method finds practical application in:
- Product Specifications and Quality Assurance: Assures conforming particle size distributions for metal powders used in powder metallurgy, additive manufacturing, and other advanced manufacturing processes.
- Manufacturing Process Control: Enables manufacturers to monitor and control raw material properties, ensuring consistent performance in downstream processing.
- Research and Development: Provides researchers with a robust technique for investigating the relationship between particle size and material properties, crucial for developing new powder-based materials.
- Compliance and Standardization: Assists in meeting industry standards and regulatory requirements for particulate metal products, supporting global trade and customer requirements.
Proper use of this test method contributes to the reproducibility and reliability of particle size data, facilitating comparison and validation across different production sites and laboratories.
Related Standards
- ASTM B330 - Test Methods for Estimating Average Particle Size of Metal Powders and Related Compounds Using Air Permeability.
- ASTM B821 - Guide for Liquid Dispersion of Metal Powders and Related Compounds for Particle Size Analysis.
- ASTM B859 - Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size Analysis.
- ASTM E456 - Terminology Relating to Quality and Statistics.
- ASTM E691 - Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.
These related standards complement ASTM B761-17(2021) by providing supporting procedures and definitions for comprehensive particle size analysis and quality control of metal powders.
Keywords: ASTM B761, particle size distribution, metal powders, X-ray sedimentation, powder metallurgy, quality control, manufacturing standards, refractory metals, additive manufacturing, sedimentation analysis
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Frequently Asked Questions
ASTM B761-17(2021) is a standard published by ASTM International. Its full title is "Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by X-Ray Monitoring of Gravity Sedimentation". This standard covers: SIGNIFICANCE AND USE 4.1 This test method is useful to both producers and purchasers of powders, as outlined in 1.1 and 1.2, in determining particle size distribution for product specifications, manufacturing control, development, and research. 4.2 Users should be aware that sample concentrations used in this test method may not be what is considered ideal by some authorities, and that the range of this test method extends into the region where Brownian movement could be a factor in conventional sedimentation. Within the range of this test method, neither the sample concentration nor Brownian movement are believed to be significant. 4.3 Reported particle size measurement is a function of both the actual particle dimension and shape factor as well as the particular physical or chemical properties being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect reported particle size results. SCOPE 1.1 This test method covers the determination of particle size distributions of metal powders. Experience has shown that this test method is satisfactory for the analysis of elemental tungsten, tungsten carbide, molybdenum, and tantalum powders, all with an as-supplied estimated average particle size of 6 μm or less, as determined by Test Method B330. Other metal powders (for example, elemental metals, carbides, and nitrides) may be analyzed using this test method with caution as to significance until actual satisfactory experience is developed (see 7.2). The procedure covers the determination of particle size distribution of the powder in the following two conditions: 1.1.1 As the powder is supplied (as-supplied), and 1.1.2 After the powder has been deagglomerated by rod milling as described in Practice B859. 1.2 This test method is applicable to particles of uniform density and composition having a particle size distribution range of 0.1 up to 100 μm. 1.2.1 However, the relationship between size and sedimentation velocity used in this test method assumes that particles sediment within the laminar flow regime. This requires that the particles sediment with a Reynolds number of 0.3 or less. Particle size distribution analysis for particles settling with a larger Reynolds number may be incorrect due to turbulent flow. Some materials covered by this test method may settle with Reynolds number greater than 0.3 if particles greater than 25 μm are present. The user of this test method should calculate the Reynolds number of the largest particle expected to be present in order to judge the quality of obtained results. Reynolds number (Re) can be calculated using the flowing equation where D = the diameter of the largest particle expected to be present, ρ = the particle density, ρ0 = the suspending liquid density, g = the acceleration due to gravity, and η = is the suspending liquid viscosity. A table of the largest particles that can be analyzed with Reynolds number of 0.3 or less in water at 35°C is given for a number of metals in Table 1. A column of the Reynolds number calculated for a 30–μm particle sedimenting in the same liquid system is given for each material also. 1.3 Units—With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the longstanding industry practice, the values in SI units are to be regarded as 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. Specific hazard information is given in Section 7. 1.5 ...
SIGNIFICANCE AND USE 4.1 This test method is useful to both producers and purchasers of powders, as outlined in 1.1 and 1.2, in determining particle size distribution for product specifications, manufacturing control, development, and research. 4.2 Users should be aware that sample concentrations used in this test method may not be what is considered ideal by some authorities, and that the range of this test method extends into the region where Brownian movement could be a factor in conventional sedimentation. Within the range of this test method, neither the sample concentration nor Brownian movement are believed to be significant. 4.3 Reported particle size measurement is a function of both the actual particle dimension and shape factor as well as the particular physical or chemical properties being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect reported particle size results. SCOPE 1.1 This test method covers the determination of particle size distributions of metal powders. Experience has shown that this test method is satisfactory for the analysis of elemental tungsten, tungsten carbide, molybdenum, and tantalum powders, all with an as-supplied estimated average particle size of 6 μm or less, as determined by Test Method B330. Other metal powders (for example, elemental metals, carbides, and nitrides) may be analyzed using this test method with caution as to significance until actual satisfactory experience is developed (see 7.2). The procedure covers the determination of particle size distribution of the powder in the following two conditions: 1.1.1 As the powder is supplied (as-supplied), and 1.1.2 After the powder has been deagglomerated by rod milling as described in Practice B859. 1.2 This test method is applicable to particles of uniform density and composition having a particle size distribution range of 0.1 up to 100 μm. 1.2.1 However, the relationship between size and sedimentation velocity used in this test method assumes that particles sediment within the laminar flow regime. This requires that the particles sediment with a Reynolds number of 0.3 or less. Particle size distribution analysis for particles settling with a larger Reynolds number may be incorrect due to turbulent flow. Some materials covered by this test method may settle with Reynolds number greater than 0.3 if particles greater than 25 μm are present. The user of this test method should calculate the Reynolds number of the largest particle expected to be present in order to judge the quality of obtained results. Reynolds number (Re) can be calculated using the flowing equation where D = the diameter of the largest particle expected to be present, ρ = the particle density, ρ0 = the suspending liquid density, g = the acceleration due to gravity, and η = is the suspending liquid viscosity. A table of the largest particles that can be analyzed with Reynolds number of 0.3 or less in water at 35°C is given for a number of metals in Table 1. A column of the Reynolds number calculated for a 30–μm particle sedimenting in the same liquid system is given for each material also. 1.3 Units—With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the longstanding industry practice, the values in SI units are to be regarded as 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. Specific hazard information is given in Section 7. 1.5 ...
ASTM B761-17(2021) is classified under the following ICS (International Classification for Standards) categories: 77.160 - Powder metallurgy. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM B761-17(2021) has the following relationships with other standards: It is inter standard links to ASTM E456-13a(2022)e1, ASTM E456-13A(2017)e3, ASTM E456-13A(2017)e1, ASTM E456-13a, ASTM E456-13ae3, ASTM E456-13ae2, ASTM E456-13ae1, ASTM B859-13, ASTM E456-13, ASTM E691-13, ASTM B330-12, ASTM E456-12, ASTM E456-12e1, ASTM E691-11, ASTM B821-10. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM B761-17(2021) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: B761 − 17 (Reapproved 2021)
Standard Test Method for
Particle Size Distribution of Metal Powders and Related
Compounds by X-Ray Monitoring of Gravity Sedimentation
This standard is issued under the fixed designation B761; 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*
D = the diameter of the largest particle expected to be
present,
1.1 This test method covers the determination of particle
ρ = the particle density,
size distributions of metal powders. Experience has shown that
ρ = the suspending liquid density,
this test method is satisfactory for the analysis of elemental
g = the acceleration due to gravity, and
tungsten, tungsten carbide, molybdenum, and tantalum
η = is the suspending liquid viscosity.
powders,allwithanas-suppliedestimatedaverageparticlesize
of 6 µm or less, as determined by Test Method B330. Other
A table of the largest particles that can be analyzed with
metal powders (for example, elemental metals, carbides, and
Reynolds number of 0.3 or less in water at 35°C is given for a
nitrides) may be analyzed using this test method with caution
numberofmetalsinTable1.AcolumnoftheReynoldsnumber
as to significance until actual satisfactory experience is devel-
calculated for a 30–µm particle sedimenting in the same liquid
oped (see 7.2). The procedure covers the determination of
system is given for each material also.
particle size distribution of the powder in the following two
conditions:
1.3 Units—With the exception of the values for density and
1.1.1 As the powder is supplied (as-supplied), and
the mass used to determine density, for which the use of the
1.1.2 After the powder has been deagglomerated by rod
gram per cubic centimetre (g/cm ) and gram (g) units is the
milling as described in Practice B859.
longstanding industry practice, the values in SI units are to be
regarded as standard.
1.2 This test method is applicable to particles of uniform
density and composition having a particle size distribution
1.4 This standard does not purport to address all of the
range of 0.1 up to 100 µm.
safety concerns, if any, associated with its use. It is the
1.2.1 However, the relationship between size and sedimen-
responsibility of the user of this standard to establish appro-
tation velocity used in this test method assumes that particles
priate safety, health, and environmental practices and deter-
sediment within the laminar flow regime.This requires that the
mine the applicability of regulatory limitations prior to use.
particles sediment with a Reynolds number of 0.3 or less.
Specific hazard information is given in Section 7.
Particle size distribution analysis for particles settling with a
1.5 This international standard was developed in accor-
largerReynoldsnumbermaybeincorrectduetoturbulentflow.
dance with internationally recognized principles on standard-
Some materials covered by this test method may settle with
ization established in the Decision on Principles for the
Reynolds number greater than 0.3 if particles greater than 25
Development of International Standards, Guides and Recom-
µm are present. The user of this test method should calculate
mendations issued by the World Trade Organization Technical
the Reynolds number of the largest particle expected to be
Barriers to Trade (TBT) Committee.
present in order to judge the quality of obtained results.
2. Referenced Documents
Reynolds number (Re) can be calculated using the flowing
equation
2.1 ASTM Standards:
B330 Test Methods for Estimating Average Particle Size of
D ~ρ 2 ρ !ρ g
0 0
Re 5 (1)
Metal Powders and Related Compounds Using Air Per-
18η
meability
where
B821 Guide for Liquid Dispersion of Metal Powders and
Related Compounds for Particle Size Analysis
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-
mittee B09.03 on Refractory Metal Powders. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2021. Published October 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1986. Last previous edition approved in 2017 as B761 – 17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0761-17R21. 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
B761 − 17 (2021)
TABLE 1 Maximum Diameter of Metal Powders and Related Compounds That Can Be Analyzed with Reynolds Number of 0.3 or Less in
Waterat35°C
A
Particle Composition Particle Density Maximum Particle Diameter Reynolds Number for 30 µm
Cobalt 8.90 33.19 0.22
Copper 8.92 33.16 0.22
Iron 7.86 34.79 0.19
Molybdenum 10.20 31.55 0.26
Nickel 8.90 33.19 0.22
Tantalum 16.60 26.46 0.44
Tantalum carbide 13.90 28.19 0.36
Titanium carbide 4.93 41.88 0.11
Tungsten 19.35 25.06 0.51
Tungsten carbide 15.63 27.03 0.41
Vanadium 6.11 38.37 .014
Vanadium carbide 5.77 39.26 0.13
A 3
Reynolds number calculated for 30 µm particle sedimenting in water at 35°C, with a density of 0.9941 g/cm and viscosity of 0.7225 cp.
B859 Practice for De-Agglomeration of Refractory Metal 5. Apparatus
Powders and Their Compounds Prior to Particle Size
5.1 Gravitational sedimentation particle size analyzer utiliz-
Analysis 3
ing X-ray extinction to determine particle concentration.
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to
6. Reagents and Materials
Determine the Precision of a Test Method
6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
3. Summary of Test Method
all reagents conform to the specifications of the Committee on
3.1 A carefully dispersed homogeneous suspension of the
Analytical Reagents of the American Chemical Society where
powder is permitted to settle in a cell scanned by a collimated 4
such specifications are available. Other grades may be used,
X-ray beam of constant intensity. The net X-ray signal is
provided it is first ascertained that the reagent is of sufficiently
inversely proportional to the sample concentration in the
high purity to permit its use without lessening the accuracy of
dispersing medium, and the particle diameter is related to the
the determination.
position of the X-ray beam relative to the top of the cell.
6.2 Dispersing Medium—Dissolve0.10gofsodiumhexam-
Cumulative mass percent versus equivalent spherical diameter
etaphosphate [(NaPO ) ] in 1000 mL of distilled or deionized
3 6
are recorded to yield a particle size distribution curve.
water.
4. Significance and Use
6.3 Cleaning Solution—Dissolve 0.5 g of laboratory deter-
4.1 This test method is useful to both producers and
gent in 1000 mL of distilled or deionized water, or prepare a
purchasers of powders, as outlined in 1.1 and 1.2, in determin- 0.1 % solution by volume of Triton X-100 using distilled or
ing particle size distribution for product specifications, manu-
deionized water.
facturing control, development, and research.
7. Hazards
4.2 Users should be aware that sample concentrations used
7.1 Precautions applying to the use of low intensity X-ray
inthistestmethodmaynotbewhatisconsideredidealbysome
units should be observed.
authorities, and that the range of this test method extends into
the region where Brownian movement could be a factor in
conventional sedimentation. Within the range of this test 3
The sole instrument of this type known to the committee as this time is the
SediGraph X-ray gravity sedimentation particle size analyzer, available from
method, neither the sample concentration nor Brownian move-
Micromeritics Instrument Corporation, 4356 Communications Drive, Norcross, GA
ment are believed to be significant.
30093. If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
4.3 Reportedparticlesizemeasurementisafunctionofboth
ation at a meeting of the responsible technical committee, which you may attend.
the actual particle dimension a
...
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