ASTM B761-06(2011)
(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
This test method is useful to both suppliers and users of powders, as outlined in 1.1 and 1.2, in determining particle size distribution for product specifications, manufacturing control, development, and research.
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.
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 Fisher number of 6 m or less, as determined by Test Method B 330. 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 ). 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 B 859.
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 m.
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 m 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 equationEquation 1 - Re = D3( - 0)0g/182whereD the diameter of the largest particle expected to be present, the particle density, 0the suspending liquid density, gthe acceleration due to gravity, and 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 35C is given for a number of metals in . A column of the Reynolds number calculated for a 30-m particle sedimenting in the same liquid system is given for each material also.
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. Specific hazard information is given in Section 7.
General Information
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Standards Content (Sample)
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Designation: B761 − 06 (Reapproved 2011)
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-suppliedFishernumberof6µmorless,
as determined byTest Method B330. Other metal powders (for
A table of the largest particles that can be analyzed with
example, elemental metals, carbides, and nitrides) may be
Reynolds number of 0.3 or less in water at 35°C is given for a
analyzed using this test method with caution as to significance
numberofmetalsinTable1.AcolumnoftheReynoldsnumber
until actual satisfactory experience is developed (see 7.2). The
calculated for a 30–µm particle sedimenting in the same liquid
procedure covers the determination of particle size distribution
system is given for each material also.
of the powder in the following two conditions:
1.1.1 As the powder is supplied (as-supplied), and
1.3 This standard does not purport to address all of the
1.1.2 After the powder has been deagglomerated by rod safety concerns, if any, associated with its use. It is the
milling as described in Practice B859.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.2 This test method is applicable to particles of uniform
bility of regulatory limitations prior to use. Specific hazard
density and composition having a particle size distribution
information is given in Section 7.
range of 0.1 up to 100 µm.
1.2.1 However, the relationship between size and sedimen-
2. Referenced Documents
tation velocity used in this test method assumes that particles
2.1 ASTM Standards:
sediment within the laminar flow regime.This requires that the
B330 Test Methods for Estimating Average Particle Size of
particles sediment with a Reynolds number of 0.3 or less.
Metal Powders and Related Compounds Using Air Per-
Particle size distribution analysis for particles settling with a
meability
largerReynoldsnumbermaybeincorrectduetoturbulentflow.
B821 Guide for Liquid Dispersion of Metal Powders and
Some materials covered by this test method may settle with
Related Compounds for Particle Size Analysis
Reynolds number greater than 0.3 if particles greater than 25
B859 Practice for De-Agglomeration of Refractory Metal
µm are present. The user of this test method should calculate
Powders and Their Compounds Prior to Particle Size
the Reynolds number of the largest particle expected to be
Analysis
present in order to judge the quality of obtained results.
E456 Terminology Relating to Quality and Statistics
Reynolds number (Re) can be calculated using the flowing
E691 Practice for Conducting an Interlaboratory Study to
equation
Determine the Precision of a Test Method
D ~ρ 2 ρ !ρ g
0 0
Re 5 (1)
18η
3. Summary of Test Method
where
3.1 A carefully dispersed homogeneous suspension of the
powder is permitted to settle in a cell scanned by a collimated
X-ray beam of constant intensity. The net X-ray signal is
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Productsand is the direct responsibility of Subcommit-
tee B09.03 on Refractory Metal Powders. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2011. Published November 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1986. Last previous edition approved in 2006 as B761 – 06. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0761-06R11. 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 − 06 (2011)
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.
inversely proportional to the sample concentration in the such specifications are available. Other grades may be used,
dispersing medium, and the particle diameter is related to the provided it is first ascertained that the reagent is of sufficiently
position of the X-ray beam relative to the top of the cell. high purity to permit its use without lessening the accuracy of
Cumulative mass percent versus equivalent spherical diameter the determination.
are recorded to yield a particle size distribution curve.
6.2 Dispersing Medium—Dissolve0.10gofsodiumhexam-
etaphosphate [(NaPO ) ] in 1000 mL of distilled or deionized
3 6
4. Significance and Use
water.
4.1 This test method is useful to both suppliers and users of
6.3 Cleaning Solution—Dissolve 0.5 g of laboratory deter-
powders,asoutlinedin1.1and1.2,indeterminingparticlesize
gent in 1000 mL of distilled or deionized water, or prepare a
distribution for product specifications, manufacturing control,
0.1 % solution by volume of Triton X-100 using distilled or
development, and research.
deionized water.
4.2 Users should be aware that sample concentrations used
inthistestmethodmaynotbewhatisconsideredidealbysome
7. Hazards
authorities, and that the range of this test method extends into
7.1 Precautions applying to the use of low intensity X-ray
the region where Brownian movement could be a factor in
units should be observed.
conventional sedimentation. Within the range of this test
7.2 Most carbides and nitrides are brittle materials and may
method, neither the sample concentration nor Brownian move-
be partially deagglomerated or fractured, or both, during the
ment are believed to be significant.
manufacturing process. Different manufacturing processes or
4.3 Reportedparticlesizemeasurementisafunctionofboth
changes in the process may affect the apparent particle size
the actual particle dimension and shape factor as well as the
distribution as determined by this test method. Thus, caution
particular physical or chemical properties being measured.
should be used in evaluating the results, especially for brittle
Caution is required when comparing data from instruments
materials.
operating on different physical or chemical parameters or with
differentparticlesizemeasurementranges.Sampleacquisition,
8. Sample Preparation
handling, and preparation can also affect reported particle size
8.1 For the as-supplied particle size distribution
results.
determinations, this step is not needed.
5. Apparatus
8.2 For laboratory-milled particle size distribution
determinations, use the rod milling technique as outlined in
5.1 Gravitational sedi
...
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