ASTM B330-07
(Test Method)Standard Test Method for Fisher Number of Metal Powders and Related Compounds
Standard Test Method for Fisher Number of Metal Powders and Related Compounds
SIGNIFICANCE AND USE
This test method provides a procedure for determining the envelope-specific surface area of powders, from which is calculated an “average” particle diameter, assuming the particles are monosize, smooth surface, nonporous, spherical particles. For this reason, values obtained by this test method will be defined as a Fisher Number. The degree of correlation between the results of this test method and the quality of powders in use will vary with each particular application and has not been fully determined.
This test method is generally applicable to all metal powders and related compounds, including carbides, nitrides, and oxides, for particles having diameters between 0.5 and 50 μm. It should not be used for powders composed of particles whose shape is too far from equiaxed, that is, flakes or fibers. In these cases, it is permissible to use the test method described only by agreement between the parties concerned. This test method shall not be used for mixtures of different powders nor for powders containing binders or lubricants. When the powder contains agglomerates, the measured surface area may be affected by the degree of agglomeration. Methods of de-agglomeration such as that referenced in 1.1 may be used if agreed upon between the parties concerned.
When an “average” particle size of powders is determined using the Fisher sub-sieve sizer, it should be clearly kept in mind that this average size is derived from the determination of the specific surface area of the powder using a relationship that is true only for powders of uniform size and spherical shape.
SCOPE
1.1 This test method uses air permeability to determine an envelope-specific surface area and its associated average equivalent spherical diameter (from 0.5 to 50 m) of metal powders and related compounds. The powders may be analyzed in their "as-supplied" (shipped, received, or processed) condition or after they have been de-agglomerated or milled by a laboratory procedure ("lab milled") such as that specified in Practice B 859. The values obtained are not intended to be absolute but are generally useful on a relative basis for control purposes.
1.2 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.
General Information
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Standards Content (Sample)
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Designation: B330 − 07
StandardTest Method for
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Fisher Number of Metal Powders and Related Compounds
This standard is issued under the fixed designation B330; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 3. Terminology
1.1 This test method uses air permeability to determine an 3.1 Definitions— Many terms used in this test method are
envelope-specific surface area and its associated average defined in Terminology B243.
equivalent spherical diameter (from 0.5 to 50 µm) of metal
3.2 Definitions of Terms Specific to This Standard:
powders and related compounds. The powders may be ana-
3.2.1 Fisher sub-sieve sizer, n—a commercially available
lyzed in their “as-supplied” (shipped, received, or processed)
permeability instrument for measuring envelope-specific sur-
condition or after they have been de-agglomerated or milled by
face area.
a laboratory procedure (“lab milled”) such as that specified in
3.2.2 envelope-specific surface area, n— specific surface
Practice B859. The values obtained are not intended to be
area of a powder as determined by gas permeametry in
absolute but are generally useful on a relative basis for control
accordance with ISO/DIS 10070.
purposes.
3.2.3 air permeability, n—measurement of air pressure drop
1.2 This standard does not purport to address all of the
across a packed bed of powder.
safety concerns, if any, associated with its use. It is the
3.2.4 de-agglomeration, n—process used to break up ag-
responsibility of the user of this standard to establish appro-
glomerates of particles.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.2.5 Fisher Number, n—calculated value equated to an
average particle diameter, assuming all the particles are spheri-
2. Referenced Documents
cal and of uniform size.
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2.1 ASTM Standards:
3.2.6 Fisher calibrator tube, n—jewel with a precision
B243 Terminology of Powder Metallurgy
orifice mounted in a tube similar to a sample tube. The
B859 Practice for De-Agglomeration of Refractory Metal
calibrator tube value is directly traceable to the master tube
Powders and Their Compounds Prior to Particle Size
maintained by Fisher.
Analysis
3.2.7 porosity of a bed of powder, n—ratio of the volume of
E456 Terminology Relating to Quality and Statistics
the void space in the powder bed to the that of the overall
E691 Practice for Conducting an Interlaboratory Study to
volume of the powder bed.
Determine the Precision of a Test Method
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3.2.8 agglomerate, n—several particles adhering together.
2.2 ISO/DIS Document:
ISO/DIS 10070 Metallic Powders: Determinations of
4. Significance and Use
Envelope-Specific Surface Area from Measurements of
4.1 This test method provides a procedure for determining
the Permeability to Air of a Powder Bed Under Steady-
the envelope-specific surface area of powders, from which is
State Flow Conditions
calculated an “average” particle diameter, assuming the par-
ticles are monosize, smooth surface, nonporous, spherical
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This test method is under the jurisdiction of ASTM Committee B09 on Metal
particles. For this reason, values obtained by this test method
Powders and Metal Powder Productsand is the direct responsibility of Subcommit-
will be defined as a Fisher Number. The degree of correlation
tee B09.03 on Refractory Metal Powders.
between the results of this test method and the quality of
Current edition approved March 15, 2007. Published April 2007. Originally
approved in 1958. Last previous edition approved in 2005 as B330 – 05. DOI:
powders in use will vary with each particular application and
10.1520/B0330-07.
has not been fully determined.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.2 This test method is generally applicable to all metal
Standards volume information, refer to the standard’s Document Summary page on
powders and related compounds, including carbides, nitrides,
the ASTM website.
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and oxides, for particles having diameters between 0.5 and 50
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. µm. It should not be used for powders composed of particles
*A Summary of Changes section appears at the end of this standard
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