1、Designation: C 925 79 (Reapproved 2000)Standard Test Method forPrecision Electroformed Wet Sieve Analysis of NonplasticCeramic Powders1This standard is issued under the fixed designation C 925; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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 the determination of the particlesize distribution of pulverized alumi
3、na and quartz for particlesizes from 45 to 5 m by wet sieving.1.2 This standard does not purport to address the safetyconcerns associated with its use. It is the responsibility of theuser of this standard to establish appropriate safety and healthpractices and determine the applicability of regulato
4、ry limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:E 161 Specification for Precision Electroformed Sieves(Square Opening Series)23. Summary of Test Method3.1 A separate dispersed suspension of the powder is wetsieved through each sieve, using vacuum and vibration. Thesieve and sa
5、mple are dried and weighed.4. Significance and Use4.1 Both suppliers and users of pulverized ceramic powderswill find this test method useful to determine particle sizedistributions for materials specifications, manufacturing con-trol, development, and research.4.2 The test method is simple, althoug
6、h tedious, usesinexpensive equipment, and will provide a continuous curvewith data obtained with standardized woven sieves.5. Apparatus5.1 Precision Electroformed Sieves, 3-in., mounted in brassframes, having nominal apertures of 45, 30, 20, 10, and 5 mand a support grid having 5.7 lines per centime
7、tre.3Interme-diate sizes may also be used.5.2 Sieving Device (Fig. 1):5.2.1 Filtering Flask (suction flask), 1-L, with side arm,5.2.2 Bchner Funnel (for example, Coors No. 2),5.2.3 O-Ring, 7.5-cm, rubber,5.2.4 Graduate, 1-L,5.2.5 Rubber Stoppers, one-hole to fit the flask and thefunnel, two-hole to
8、fit the graduate,5.2.6 Quantity of glass tubing and rubber tubing,5.2.7 Metal Rod, 15 to 20-cm, about 5 mm in diameter, and,5.2.8 Vacuum Source.5.3 Ultrasonic Cleaner, required to clean all sieves below20 m. It should be low-powered (for example, 100 W).5.4 Analytical Balance, capable of weighing up
9、 to 100 g andhaving at least three significant digits after the decimal.5.5 Drying Oven, capable of maintaining 110 6 5C.5.6 Desiccator, containing magnesium perchlorate or othersuitable desiccant.1This test method is under the jurisdiction of ASTM Committee C-21 onCeramic Whitewares and Related Pro
10、ducts and is the direct responsibility ofSubcommittee C21.07 on Nonplastics.Current edition approved Dec. 28, 1979. Published February 1980.2Annual Book of ASTM Standards, Vol 14.02.3A support grid, manufactured by Buckbee Mears Co., 245 E. Sixth St., St. Paul,MN 55101, has been found satisfactory f
11、or this purpose.FIG. 1 Wet Sieving Apparatus1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.6. Reagents and Materials6.1 Water, visually clear and particle free, not necessarilydistilled, at room temperature or slightly above.6.2 Sieving Solution, a dispersing
12、 media consisting of 0.1weight % solution of sodium hexametaphosphate or sodiumpyrophosphate in water.6.3 Drying Agents, acetone or methyl alcohol, commercialgrade.7. Sampling7.1 Since the amount of sample used in the determination isquite small, great care must be taken to avoid segregation.Gross s
13、amples must be cut down very carefully using splitters,rifflers, or simple cone and quartering techniques. Adjusting theportion to an exact weight must be avoided. That is, arepresentative portion must be extracted from the analyticalsample and all of it weighed and used.8. Preparation of Apparatus8
14、.1 Cleaning of SievesUse sufficient sieving solution tocover the sieve when suspended near the bottom of theultrasonic tank. (Some organic liquids are better but create adefinite explosion hazard.) Turn on the generator for about 30s. Fine sieves may need multiple treatments. (Exposure toultrasonic
15、energy for periods exceeding 30 s at one time maydamage the sieves.) After each cleaning carefully examine thesieve against a light, using a magnifying glass, for blockagesand breaks. (Breaks can be repaired with epoxy resin.) Sievesof 20 m and finer should be cleaned after each analysis. Rinsein cl
16、ear water and dry at 110C.8.2 Collector and Vacuum ControlAssemble apparatus asshown in Fig. 1.9. Calibration and Standardization9.1 Calibration of SievesThis must be done for highlyaccurate analyses or to verify the apertures that may not bewithin the quoted 2-m tolerance. The calibration procedure
17、 isgiven in Appendix X1 of Specification E 161.10. Procedure10.1 Wash the sieves with the sieving solution, rinse withwater and then with the drying agent, dry at 110C for 15 min,cool in the desiccator, and weigh to at least the nearest 1 mg.10.2 Sample Size is somewhat dependent upon density, butth
18、e following schedule is satisfactory for alumina and quartz:Nominal SieveApertures, mSample Weight(approximate), g45, 30, 20 1.015, 10 0.45 0.1510.3 Weigh the required amount of sample into a 100-mLbeaker, fill half with sieving solution (containing the dispersingagent), and disperse by placing beak
19、er in ultrasonic bath for 1min. Microscopical examination of the particles after disper-sion may be helpful in determining if the dispersion iscomplete.10.4 Wash the dispersed sample onto the sieve using a washbottle containing the sieving solution, turn on vacuum (amaximum of 15 in. of water), and
20、agitate. Continuously addsieving solution, at a rate sufficient to maintain a small amountin the sieve, until about 1 L has passed. Below 6 m the amountof liquid required is less due to the time for sieving. Agitate bysharp tapping on the sieve frame with the metal rod. For sievesabove 30 m the liqu
21、id runs quickly enough without vacuum sothat the air-bleed valve can be opened. The bleed-line shouldbe pinched occasionally, however, to draw the larger particlesthrough, but care must be taken to avoid damage to the sieve.For apertures of 10 m or less, when the sieving appearscomplete (that is, th
22、e filtrate is clear) or the rate of throughputbecomes very slow, draw the sieve down to near dryness withthe vacuum. Remove the sieve from the sieving device andpartially immerse it in the sieving solution in the ultrasonictank for about 1 min. The particles that have blocked theapertures will be fo
23、rced back into the sieve. Regular sieving isthen continued. This procedure must be repeated until the washsolution in the ultrasonic tank remains clear (not visuallycloudy) after washing. This may be as many as 4 to 5 times forthe 5-m sieve to assure that the sieving is complete.10.5 Rinse with dist
24、illed water to remove any sievingsolution and then rinse with drying agent, dry for 15 min at110C, cool in the desiccator, and weigh sieve and sample.10.6 Triplicate replications are advised to assure repeatabil-ity.11. Calculation and Report11.1 Report the “weight percent greater than aperture” for
25、each replicate and for each sieve along with the calibrated sieveopenings. Calculate as follows:W 5B 2 CD3 100 (1)where:W = weight percent greater than aperture,B = weight of sieve with sample, g,C = weight of empty sieve, g, andD = original sample weight, g.12. Precision and Bias12.1 PrecisionThe p
26、recision of the procedure in TestMethod C 925 is being determined.12.2 BiasThe true value of the particle size can only bedefined in terms of the test method. Within this limitation, thistest method has no known bias.13. Keywords13.1 ceramic powders; particle size distribution; precisionelectroforme
27、d sieves; wet-sievesC 9252The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connectionwith any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any suchpatent ri
28、ghts, and the risk of infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either f
29、or revision of this standard or for additional standardsand should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
30、make yourviews known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM, 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 above address or at610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website (www.astm.org).C 9253
