Designation: C958 − 92 (Reapproved 2014)
Standard Test Method for
Particle Size Distribution of Alumina or Quartz by X-Ray
Monitoring of Gravity Sedimentation1
This standard is issued under the fixed designation C958; 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 4. Summary of Test Method
1.1 This test method covers the determination of the particle 4.1 An aqueous homogeneous dispersion of the specimen is
size distribution of alumina or quartz powders in the range permitted to settle in a cell. The decrease in particle concen-
from 0.5 to 50 µm and having a median particle diameter from tration over a programmed settling distance is monitored by an
2.5 to 10 µm using a sedimentation method. This test method X-ray beam passing through the sedimenting dispersion to a
is one of several found valuable for the measurement of detector. The specimen concentration at any given sedimenta-
particle size. Instruments used for this test method employ a tion distance is inversely proportional to the X-ray flux and the
constant intensity X-ray beam that is passed through a sedi- equivalent diameter (spherical) is calculated from Stokes’ law.
menting dispersion of particles. NOTE 1—Refer to Terminology C242. Most equipment manufacturers
1.2 The values stated in SI units are to be regarded as the refer to this as the equivalent spherical diameter.
standard. The values given in parentheses are for information 5. Apparatus
only.
5.1 X-Ray Sedimentation Apparatus.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5.2 Ultrasonic Probe or Bath—An ultrasonic probe approxi-
responsibility of the user of this standard to establish appro- mately 13-mm (1⁄2-in.) in diameter and approximately 50 to
priate safety and health practices and determine the applica- 100 W or an ultrasonic bath of approximately 0.3 W/cm2 (2
bility of regulatory limitations prior to use. For specific hazard W/in.2).
statements, see Section 7. 6. Reagents
2. Referenced Documents 6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
2.1 ASTM Standards:2 all reagents shall conform to the specifications of the Commit-
C242 Terminology of Ceramic Whitewares and Related tee on Analytical Reagents of the American Chemical Society,
Products where such specifications are available.3 Other grades may be
E177 Practice for Use of the Terms Precision and Bias in used, provided it is first ascertained that the reagent is of
ASTM Test Methods sufficiently high purity to permit its use without lessening the
E691 Practice for Conducting an Interlaboratory Study to accuracy of the determination.
Determine the Precision of a Test Method
6.2 Distilled or Deionized Water.
3. Terminology 6.3 Dispersing Liquid—Dissolve 1.0 g/L of reagent grade
sodium hexametaphosphate in distilled or deionized water.
3.1 For definitions of terms used in this test method, refer to
Discard any remaining solution after six weeks from date of
Terminology C242.
preparation.
7. Hazards
1
This test method is under the jurisdiction of ASTM Committee C21 on Ceramic 7.1 Precautions applying to the use of low-intensity X-rays
Whitewares and Related Productsand is the direct responsibility of Subcommittee
should be observed.
C21.04 on Raw Materials.
Current edition approved Jan. 1, 2014. Published February 2014. Originally
3
approved in 1992. Last previous edition approved in 2007 as C958–92(2007) DOI: Reagent Chemicals, American Chemical Society Specifications, American
10.1520/C0958-92R14. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
C958 − 92 (2014)
7.2 Users should be aware that sample concentrations used 8.7 Run the particle size distribution in the “Percent Finer
in this test method may be higher than those considered ideal Than” mode using a starting diameter of 50 µm. Calculate the
by some authorities and that the range of this test method instrument rates using a density of 3.95 g/m3 for alumina and
extends into the region where Brownian motion could be a 2.65 g/m3 for silica.
factor in conventional gravity sedimentation. Within the range 8.7.1 It is recommended that 8.6 and 8.7 be repeated in
of this test method neither the sample concentration nor order to increase confidence in the analysis and to ensure that
Brownian motion are believed to be significant. good dispersion has been achieved.
8.8 Upon completion of the analyses, rinse or clean the
8. Procedure instrument for the following run as suggested by the manufac-
8.1 Prepare the instrument for use according to the manu- turer.
facturer’s instructions. 9. Precision and Bias4
8.2 If necessary, manually zero the instrument with the cell 9.1 Interlaboratory Test Program—An interlaboratory study
filled with the dispersing liquid. of the particle size distribution of alumina and quartz was run
in 1989. Nine laboratories participated in the study, which
8.3 Transfer 2.5 g of the dry specimen (or an equivalent
included three different models of instruments, with each
amount of a slurried specimen) into a 50-mL beaker and add 30
laboratory testing five specimens of each material. Except for
mL of the dispersing liquid. Mix well using a rubber policeman
the use of only two materials, Practice E691 was followed for
to break up any clumping.
the design and analysis of the data.
8.3.1 The amount of specimen required may vary between
instruments. Adjust the specimen weight to reduce the X-ray 9.2 Test Result—The precision information given in 9.3 in
intensity according to the manufacturer’s recommended con- the units of equivalent spherical diameter (in micrometres) is
ditions. for the comparison of two test results, each of which is the
average of five test determinations.
8.4 Disperse the specimen using either of the instrument’s 9.3 Precision:
given in 8.4.1 and 8.4.2:
Test range 1 to 50 µm
8.4.1 Ultrasonic Bath—Place the beaker in the bath and 95 % repeatability limit 10 % (5 to 21 %) of the test result
disperse the specimen for 5 min with frequent stirring. It is (within laboratory)
95 % reproducibility limit 15 % (8 to 29 %) of the test result
beneficial to cause the liquid level in the bath and beaker to (between laboratories)
match. The above terms repeatability limit and reproducibility limit
8.4.2 Ultrasonic Probe—Insert the probe into the beaker are used as specified in Practice E177. The respective percent
and disperse the specimen for 1 min. Do not allow the coefficients of variation among test results may be obtained by
temperature of the dispersion liquid to rise more than 2°C. dividing the above numbers by 2.8.
8.5 Add a 25-mm (1-in.) magnetic stirring bar to the beaker, 9.4 Bias—No absolute method of particle size determination
and place the beaker in the instrument’s cell compartment. is recognized. Therefore, no justifiable statement can be made
Adjust the stirring rate to produce a slight vortex. on the bias of the procedure in this test method.
8.5.1 If an instrument provides a different method for 10. Keywords
stirring and circulating the dispersion, be sure to follow the
appropriate procedure. 10.1 alumina; gravity sedimentation; particle size; particle
size distribution; quartz; sedimentation
8.6 Fill the cell with the dispersed slurry according to the
manufacturer’s instructions, making sure that no air bubbles 4
Supporting data have been filed at ASTM International Headquarters and may
remain in the cell. be obtained by requesting Research Report RR: C21-1004.
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