ASTM B859-95(2000)
(Practice)Standard Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size Analysis
Standard Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size Analysis
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 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. For specific precautionary statements, see Note 2.
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Designation: B 859 – 95 (Reapproved 2000)
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 B 859; 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 4. Significance and Use
1.1 This practice covers the de-agglomeration of refractory 4.1 Refractory metal powders, such as tungsten and molyb-
metal powders and their compounds in preparation for particle denum, are usually produced by hydrogen reduction at high
size analysis. temperatures. Thus, they usually contain numerous large,
1.2 Experience has shown that this practice is satisfactory strongly-sintered agglomerates. Many of the manufacturing
for the de-agglomeration of elemental tungsten, molybdenum, processes using these powders involve a milling step or some
rhenium, and tantalum metal powders, and tungsten carbide. similar treatment or depend on the individual particulate size,
Other metal powders (for example, elemental metals, carbides, not on the agglomerate size. Thus, a knowledge of the
and nitrides) may be prepared for particle size analysis using individual particulate size distribution, not the agglomerate
this practice with caution as to effectiveness until actual size distribution, is usually desired from a particle size analysis
satisfactory experience is developed. of these powders. This practice provides a procedure for
1.3 This standard does not purport to address all of the breaking down agglomerates into their constituent particles
safety concerns, if any, associated with its use. It is the (de-agglomeration), without excessive fracture of the indi-
responsibility of the user of this standard to establish appro- vidual particles. The procedure is often referred to as labora-
priate safety and health practices and determine the applica- tory milling or rod milling.
bility of regulatory limitations prior to use. For specific 4.2 The laboratory milling conditions specified in this guide
precautionary statements, see Note 2. have been in use since 1965 as part of Test Method B 430. This
guide was first published as a separate, stand-alone standard in
2. Referenced Documents
1995 because of its applicability in preparing powder samples
2.1 ASTM Standards: for analysis by other methods (for example, Test Methods
B 243 Terminology of Powder Metallurgy
B 761 and B 822), in addition to Test Method B 430. Informa-
B 330 Test Method for Average Particle Size of Powders of tion on the development and establishment of the milling
Refractory Metals and Their Compounds by the Fisher
conditions here specified can be found in the footnoted
2 4
Sub-Sieve Sizer reference.
B 430 Test Method for Particle Size Distribution of Refrac-
4.3 The milling procedure described in this practice does
tory Metal Powders and Related Compounds by Turbidim- not necessarily break down only agglomerates without fractur-
etry
ing individual particles; some particle fracture may occur in
B 761 Test Method for Particle Size Distribution of Refrac- certain powders. However, use of this practice does provide
tory Metals and Their Compounds by X-Ray Monitoring consistent particle size analysis results that have been found to
of Gravity Sedimentation
relate well to powder behavior in numerous manufacturing
B 821 Guide for Liquid Dispersion of Metal Powders and processes.
Related Compounds for Particle Size Analysis
4.4 This practice shall be used for the de-agglomeration of
B 822 Test Method for Particle Size Distribution of Metal the refractory metal powders and compounds listed in 1.1,
Powders and Related Compounds by Light Scattering
when an evaluation of the individual particulate size distribu-
tion is required from the subsequent particle size analysis. It
3. Terminology
shall not be used when the agglomerate (as-is or as-supplied)
3.1 Definitions—Definitions of powder metallurgy terms
size distribution is desired.
can be found in Terminology B 243.
4.5 This practice may be used in preparing samples for Test
Michaels, A. I., “Turbidimetric Particle Size Distribution Theory: Application
This practice is under the jurisdiction of ASTM Committee B-9 on Metal to Refractory Metal and Oxide Powders,” 1958 Symposium on Particle Size
Powders and Metal Powder Products and is the direct responsibility of Subcom- Measurement, ASTM STP 234, ASTM, 1959, pp. 207–244.
mittee B09.03 on Refractory Metal Powders. Buerkel, W. A., “Turbidimetric Particle Size Analysis as Applied to Tungsten
Current edition approved Jan. 15, 1995. Published March 1995. Powder and the Carbide Industry,” Handbook of Metal Powders, A. Poster, ed.,
Annual Book of ASTM Standards, Vol 02.05. Rei
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