ASTM C1282-00(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:C 1282–00 (Reapproved 2006)
Standard Test Method for
Determining the Particle Size Distribution of Advanced
Ceramics by Centrifugal Photosedimentation
This standard is issued under the fixed designation C 1282; 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 predetermined times related to the sedimentation of specific
Stokes’ diameters (Note 1), the optical absorbance is recorded
1.1 This test method covers determination of the particle
and compared to the initial value to determine the fraction of
size distribution of advanced ceramic powders specifically
the total sample that has sedimented a specific distance. A
silicon nitride and carbides, in the range of 0.1 to 20 µm,
volume-based size distribution is calculated from the
having a median particle diameter from 0.5 to 5.0 µm.
absorbance-time data. The results are reported as equivalent
1.2 The procedure described in this test method may be
diameter (spherical) (Note 2) since particles in these powders
applied successfully to other ceramic powders in this general
are not truly spherical.
size range, provided that appropriate dispersion procedures are
developed. It is the responsibility of the user to determine the
NOTE 1—This diameter in µm is referred to as D in the equation given
applicability of this test method to other materials.
below.
NOTE 2—Refer to Terminology C 242 for the ASTM definition of this
1.3 The values stated in SI units are to be regarded as the
term. Most equipment manufacturers refer to this as the equivalent
standard. The values given in parentheses are for information
spherical diameter.
only.
X
1.4 This standard does not purport to address all of the
18 · log
h
X
safety concerns, if any, associated with its use. It is the 2 8
D 5 3 10 (1)
~p – p !u t
responsibility of the user of this standard to establish appro-
s f
priate safety and health practices and determine the applica-
where:
bility of regulatory limitations prior to use.
h = viscosity of the fluid, cP,
X = distance from the middle of the centrifugal disc cell to the point
2. Referenced Documents
in the cell where sedimentation starts,
X = distance from the center of the centrifugal disc cell to the point
2.1 ASTM Standards:
where the light beam intersects the particle
C 242 Terminology of Ceramic Whitewares and Related
t = time for the particle to settle, s
Products
r = particle density, g/cm ,
s
r = fluid density, g/cm , and
f
3. Terminology
u = rotational angular velocity, rad/s.
3.1 Definitions—RefertoTerminologyC 242fordefinitions
of terms used in this test method.
4.2 The instruments that have been found suitable for this
test method incorporate microcomputers that control instru-
4. Summary of Test Method
ment operation and perform all required data acquisition and
4.1 A homogeneous aqueous dispersion of the powder is
computation functions.
prepared. While kept in a thoroughly mixed condition, a small
aliquot is transferred to the analyzer sample cell, which is
5. Significance and Use
placed in the instrument and subjected to a controlled centrifu-
5.1 Manufacturers and users of advanced ceramic powders
gal acceleration at a known or controlled temperature. At
will find this test method useful for determining the particle
size distribution of these materials for product specification,
quality control, and research and development.
This test method is under the jurisdiction of ASTM Committee C28 on
Advanced Ceramics and is the direct responsibility of Subcommittee C28.03 on
Physical Properties and Performance. 6. Apparatus
Current edition approved Jan. 1, 2006. Published January 2006. Originally
6.1 Centrifugal Particle Size Distribution Analyzer—The
approved in 1994. Last previous edition approved in 2000 as C 1282 – 00.
analyzer shall incorporate a centrifuge capable of subjecting an
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
homogeneous dispersion of the sample to centrifugal accelera-
Standards volume information, refer to the standard’s Document Summary page on
tion in specially designed sample cells. A collimated beam of
the ASTM website.
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C 1282–00 (2006)
visible light (either monochromatic or broad-band) shall to accomplish deagglomeration of the particles. The extent of
traversethesamplecellatadefineddistancefromthetopofthe deagglomeration is expected to be different for powders
cell. The change in photo-extinction resulting from sedimen- produced by different processes. An alternate approach is to
tation of the sample shall be measured by a photo-detector and ultrasonicate for 3 min continuously before pH and tempera-
appropriate electronic circuits and used to calculate the ture check. Readjust the pH, if necessary, after ultrasonic
volume-based size distribution of the sample. application. Keep stirring the sample continuously, and test it
6.2 Ultrasonic Probe, consisting of a 200 to 300-W power as soon as practical to prevent reagglomeration.
unit, ultrasonic transducer, and 13-mm ( ⁄2-in.) diameter probe. 8.1.2 Add a 25-mm (1-in.) stirring bar to the beaker, and
6.3 Balance, top-loading, accurate to 10 6 0.1 g. place it on a magnetic stirrer. Stir for approximately 3 min in
6.4 Stirrer, magnetic, with 25-mm (1-in.) and 19-mm ( ⁄4 a cold water bath to bring the sample to ambient temperature.
in.) stirring bars. Continue stirring at constant temperature.
6.5 Thermometer,mercuryoralcohol,0to50°C,accurateto 8.2 Analyzer Preparation:
0.5°C. 8.2.1 To warm up the analyzer, apply power for a minimum
6.6 Sample Cells, as supplied by the instrument manufac- of10minpriortotesting.Conductthewarmupwiththesample
turer. compartment closed. Make certain that the ventilation airflow
is not restricted by adjacent equipment, papers, or other
7. Reagents
materials. Check the printer to ensure a sufficient supply of
paper exists. Clean a pair of sample cells and caps, rinse with
7.1 Purity of Reagents—Reagent grade chemicals shall be
the 0.1 % Darvan C solution, and store inverted on absorbent
used in all tests. Unless otherwise indicated, it is intended that
paper.
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
NOTE 4—The concentration of the sample may require dilution with
where such spe
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