1、Designation: C 1282 00 (Reapproved 2006)Standard Test Method forDetermining the Particle Size Distribution of AdvancedCeramics by Centrifugal Photosedimentation1This standard is issued under the fixed designation C 1282; the number immediately following the designation indicates the year oforiginal
2、adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the particlesize distribut
3、ion of advanced ceramic powders specificallysilicon nitride and carbides, in the range of 0.1 to 20 m,having a median particle diameter from 0.5 to 5.0 m.1.2 The procedure described in this test method may beapplied successfully to other ceramic powders in this generalsize range, provided that appro
4、priate dispersion procedures aredeveloped. It is the responsibility of the user to determine theapplicability of this test method to other materials.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not
5、 purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards
6、:2C 242 Terminology of Ceramic Whitewares and RelatedProducts3. Terminology3.1 DefinitionsRefer to Terminology C 242 for definitionsof terms used in this test method.4. Summary of Test Method4.1 A homogeneous aqueous dispersion of the powder isprepared. While kept in a thoroughly mixed condition, a
7、smallaliquot is transferred to the analyzer sample cell, which isplaced in the instrument and subjected to a controlled centrifu-gal acceleration at a known or controlled temperature. Atpredetermined times related to the sedimentation of specificStokes diameters (Note 1), the optical absorbance is r
8、ecordedand compared to the initial value to determine the fraction ofthe total sample that has sedimented a specific distance. Avolume-based size distribution is calculated from theabsorbance-time data. The results are reported as equivalentdiameter (spherical) (Note 2) since particles in these powd
9、ersare not truly spherical.NOTE 1This diameter in m is referred to as D in the equation givenbelow.NOTE 2Refer to Terminology C 242 for the ASTM definition of thisterm. Most equipment manufacturers refer to this as the equivalentspherical diameter.D2518h logX1X2ps pf!u2t3 108(1)where:h = viscosity o
10、f the fluid, cP,X1= distance from the middle of the centrifugal disc cell to the pointin the cell where sedimentation starts,X2= distance from the center of the centrifugal disc cell to the pointwhere the light beam intersects the particlet = time for the particle to settle, srs= particle density, g
11、/cm3,rf= fluid density, g/cm3, andu = rotational angular velocity, rad/s.4.2 The instruments that have been found suitable for thistest method incorporate microcomputers that control instru-ment operation and perform all required data acquisition andcomputation functions.5. Significance and Use5.1 M
12、anufacturers and users of advanced ceramic powderswill find this test method useful for determining the particlesize distribution of these materials for product specification,quality control, and research and development.6. Apparatus6.1 Centrifugal Particle Size Distribution AnalyzerTheanalyzer shal
13、l incorporate a centrifuge capable of subjecting anhomogeneous dispersion of the sample to centrifugal accelera-tion in specially designed sample cells. A collimated beam of1This test method is under the jurisdiction of ASTM Committee C28 onAdvanced Ceramics and is the direct responsibility of Subco
14、mmittee C28.03 onPhysical Properties and Performance.Current edition approved Jan. 1, 2006. Published January 2006. Originallyapproved in 1994. Last previous edition approved in 2000 as C 1282 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.visible light (either monochromatic or broad-band)
16、 shalltraverse the sample cell at a defined distance from the top of thecell. The change in photo-extinction resulting from sedimen-tation of the sample shall be measured by a photo-detector andappropriate electronic circuits and used to calculate thevolume-based size distribution of the sample.6.2
17、Ultrasonic Probe, consisting of a 200 to 300-W powerunit, ultrasonic transducer, and 13-mm (12-in.) diameter probe.6.3 Balance, top-loading, accurate to 10 6 0.1 g.6.4 Stirrer, magnetic, with 25-mm (1-in.) and 19-mm (34in.) stirring bars.6.5 Thermometer, mercury or alcohol, 0 to 50C, accurate to0.5C
18、.6.6 Sample Cells, as supplied by the instrument manufac-turer.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American
19、Chemical Society,where such specifications are available.37.2 Darvan C4Dispersing FluidDissolve 5.0 g Darvan C(ammonium salt of polymethacrylic acid) in 95 cm3distilledwater (Note 3).NOTE 3These reagents are adequate to cover the range of samples upto a maximum particle diameter of 20 m.7.3 pH Adjus
20、tersFresh ammonium hydroxide (NH4OH)at 5 to 10 % strength is a common reagent used to raise pHwhile fresh nitric acid (HNO3) at 5 to 10 % strength is acommon reagent to lower pH.8. Procedure8.1 Sample Preparation and Dispersion:8.1.1 Add the appropriate sample mass of powder, usually 1g, to 250 cm3d
21、ispersing medium in a 500-cm3beaker. Thedispersing medium consists of 250 cm3of distilled water towhich 0.3 g of dispersing liquid is added.8.1.1.1 Sample DispersionPlace the beaker containingsample in an ice water bath so that the temperature of thesample does not exceed approximately 30C. Adjust t
22、he pH ofthe sample to 9.06 0.2 to ensure adequate dispersion aided bythe chemical environment. Deagglomerate the sample byinserting the ultrasonic transducer into the dispersing liquid/sample in a beaker. Ensure that the transducer is approximately10.0 mm above the bottom of the sample beaker. Apply
23、 theultrasonic energy at 40 W or higher for 1.0 min, and allow thesample to settle for 1.0 min. Repeat this procedure three timesso that the total ultrasonic energy application time is 3 min.This high level of mechanical energy application is necessaryto accomplish deagglomeration of the particles.
24、The extent ofdeagglomeration is expected to be different for powdersproduced by different processes. An alternate approach is toultrasonicate for 3 min continuously before pH and tempera-ture check. Readjust the pH, if necessary, after ultrasonicapplication. Keep stirring the sample continuously, an
25、d test itas soon as practical to prevent reagglomeration.8.1.2 Add a 25-mm (1-in.) stirring bar to the beaker, andplace it on a magnetic stirrer. Stir for approximately 3 min ina cold water bath to bring the sample to ambient temperature.Continue stirring at constant temperature.8.2 Analyzer Prepara
26、tion:8.2.1 To warm up the analyzer, apply power for a minimumof 10 min prior to testing. Conduct the warmup with the samplecompartment closed. Make certain that the ventilation airflowis not restricted by adjacent equipment, papers, or othermaterials. Check the printer to ensure a sufficient supply
27、ofpaper exists. Clean a pair of sample cells and caps, rinse withthe 0.1 % Darvan C solution, and store inverted on absorbentpaper.NOTE 4The concentration of the sample may require dilution with0.1 % Darvan C solution to meet the optical absorbance tolerancespecified in the instrument operating manu
28、al. Thorough mixing mustaccompany any dilution of the sample.8.2.2 If required by the manufacturers operating manual,check and adjust the zero and full-scale settings. Theseadjustments can be crucial to reliable and reproducible mea-surements.8.2.3 Input the test parameters (sample and fluid density
29、,fluid viscosity, test range, sedimentation distance, and centri-fuge speed) according to the manufacturers operating manual.Set the fluid viscosity at the value corresponding to the actualroom temperature (see Table 1). Set the range such that thevolume percent greater than the maximum diameter is
30、certainlyzero and the volume percent finer than the minimum diameteris less than 10 % (cumulative percent oversize greater than90 %). Preliminary test runs may be required to establish therange and the size of the divisions necessary to achieve the testlimits. The test range and division settings sh
31、all provide aminimum of ten divisions within the test range.8.2.4 If required by the manufacturers operating manual,conduct a blank test with clean dispersant fluid in the sampleand reference cells.8.3 Test Performance:8.3.1 Adjust the rate of the magnetic stirrer to produce aslight vortex in the sa
32、mple dispersion. Withdraw an appropriatevolume of sample from the center of the dilute dispersion witha disposable plastic pipet. Make certain that the dispersion ismixed thoroughly by vigorous pumping with the pipet (avoidstrong agitation, which would create bubbles). Completelytransfer the withdra
33、wn sample to the drained sample cell. Insert3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Reagent Chemicals and Standards,byJoseph Rosin, D. Van Nostra
34、nd Co., Inc., New York, NY, and the United StatesPharmacopeia.4Darvan C is a trademarked product of R.T. Vanderbilt Company, Inc., Norwalk,CT 06856-5150.TABLE 1 Viscosity Coefficients of WaterATemperature, C 20 21 22 23 24 25 26 27 28 29Viscositycoefficient,mPa*s or cP1.01 0.98 0.96 0.94 0.92 0.89 0
35、.87 0.86 0.84 0.82AViscosity coefficient values to two decimal places have been found satisfactoryfor this test method.C 1282 00 (2006)2the cell cap, carefully wipe all outer surfaces of the cell, placein the centrifuge, and start the test. Monitor the absorbancedisplay on the instrument to ensure t
36、hat the initial absorbanceis within the specified tolerance at the beginning of the test. Ifnot, refer to Note 4. When the test is completed, remove thesample cell, clean immediately, and rinse with dispersant fluid.9. Presentation of Data9.1 Analyzer PrintoutThe analyzers that have been foundsuitab
37、le for this test method render data printouts that providea permanent record of the test conditions and graphic recordsof the size distribution. These printouts may provide sufficientinformation for many purposes.10. Fluid Densities and Viscosity Coefficients10.1 Table 1 lists the viscosity coeffici
38、ents for water over thetemperature range of 20 to 29C. Use these values for theDarvan C solution. Use a density of 1.00 g/cm3for thesesolutions.11. Additional Data Presentations11.1 The analyzers that have been found suitable for usewith this test method produce a printed report that may includea cu
39、mulative size distribution table showing the volumepercent oversize, starting with the programmed maximumdiameter. The incremental divisions are selectable by theoperator in some operating modes and, in others, determinedby the microcomputer in the instrument.12. Precision and Bias12.1 PrecisionNo s
40、tatement of precision can be madesince round-robin testing has not been completed.12.2 BiasIt is not possible to discuss the bias of the resultsobtained using this test method since no absolute method ofparticle size distribution is recognized.13. Keywords13.1 advanced ceramics; particle size distri
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44、known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 1282 00 (2006)3
