1、Designation: B821 10Standard Guide forLiquid Dispersion of Metal Powders and RelatedCompounds for Particle Size Analysis1This standard is issued under the fixed designation B821; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide covers the dispersion in liquids of metalpowders and related compounds for subsequent use in parti
3、clesize analysis instruments. This guide describes a generalprocedure for achieving and determining dispersion; it alsolists procedures that are currently in general use for certainmaterials.1.2 This guide is limited to metal powders and related metalcompounds. However, the general procedure describ
4、ed hereinmay be used, with caution as to its significance, for otherparticulate materials, such as ceramics, pigments, minerals, etc.1.3 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.4 This standard does not purport
5、 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:2B243 T
6、erminology of Powder MetallurgyB430 Test Method for Particle Size Distribution of Refrac-tory Metal Powders and Related Compounds by Turbidim-etryB761 Test Method for Particle Size Distribution of MetalPowders and Related Compounds by X-Ray Monitoring ofGravity SedimentationB822 Test Method for Part
7、icle Size Distribution of MetalPowders and Related Compounds by Light Scattering3. Terminology3.1 DefinitionsDefinitions of powder metallurgy termscan be found in Terminology B243.4. Significance and Use4.1 The method of powder dispersion in a liquid has asignificant effect on the results of a parti
8、cle size distributionanalysis. The analysis will show a too-coarse, unstable, ornonrepeatable distribution if the powder has not been dispersedadequately. It is therefore important that parties wishing tocompare their analyses use the same dispersion technique.4.2 This guide provides established pow
9、der dispersion tech-niques for certain materials and the means of deriving tech-niques for materials not listed. It should be used by all partiesperforming liquid-dispersed particle size analysis of all of thematerials covered by this guide (see 1.1, 1.2, and 4.1).4.3 This guide should be used in th
10、e preparation of powdersfor use in Test Methods B430, B761, and B822 and otherprocedures that analyze metal powder particle size distribu-tions in liquid-dispersed systems.5. Apparatus5.1 Microscope, suitable for observation of particles in thesize range of 5 to 1000 m.5.2 Ultrasonic Probe,12 -in. (
11、25.4-mm) tip, with the powerlevel to be determined by this guide.5.3 Ultrasonic BathPower level to be determined by thisguide.6. Reagents6.1 Purity of ReagentsReagent grade chemicals should beused in all tests. Unless otherwise indicated, it is intended thatall reagents should conform to the specifi
12、cations of theCommittee on Analytical Reagents of the American ChemicalSociety.3Other grades may be used, provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.6.2 SurfactantsSuggested surfactants are lis
13、ted in Table 1and footnotes 4 through 6.4,5,61This guide is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.02 on Base Metal Powders.Current edition approved Sept. 1, 2010. Published September 2010. Original
14、lyapproved in 1992. Last previous edition approved 2007 as B821 02(2007). DOI:10.1520/B0821-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Documen
15、t Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. General Dispersion Procedure7.1 The general procedure for determining and achievin
16、gproper dispersion is outlined in Fig. 17and described in detailbelow:7.1.1 Place a test portion of the powder to be analyzed in abeaker containing the carrier liquid, selected according to7.1.2.7.1.2 Selection of Carrier Liquid:NOTE 1The selected carrier liquid must be compatible with thecomponents
17、 of the instrument used for the particle size analysis.7.1.2.1 If the powder reacts with, or is soluble in, water andorganic liquids, it must be analyzed in the dry state, and theremainder of this guide is then not applicable.3Reagent Chemicals, American Chemical Society Specifications , AmericanChe
18、mical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Roc
19、kville,MD.4Allen, T., Particle Size Measurement, 4th Edition, Chapman and Hall, London,UK, 1991.5Nelson, R. D., Dispersing Powders in Liquids, Elsevier, New York, NY, 1988.6SediGraph III 5120 Operators Manual, Micromeritics Corporation, Norcross,GA, 1998, pp. C-3, C-4, and H-3.7Microtrac Course Manu
20、al, Leeds and Northrup Company, St. Petersburg, FL,1989.TABLE 1 Recommended Dispersion ProceduresMaterialCarrierLiquidSurfactantSurfactantConcentrationUltrasonicTreatmentTypePowerLevel, WTime, minChromium carbide water none . noneorAbath.25.5Copper water Tween 21B35 dropsCbath 80 1Ferroalloys isopro
21、pyl alcohol Tween 21B10 % bath 80 1Iron/steel water Tween 21B35 dropsCbath 80 1Manganese sulfide water Tween 21B35 dropsCbath 80 1Molybdenum water sodium hexametaphosphate 0.01 % probeorbathorAbath16080253105Nickel water Tween 21B35 dropsCbath 80 1Tantalum water sodium hexametaphosphate 0.01 % probe
22、orbath16080310Tantalum carbide water sodium hexametaphosphate 0.01 % probeorbathorAbath16080253105Tungsten water sodium hexametaphosphate 0.01 % probeorbathorAbath16080253105Tungsten carbide water sodium hexametaphosphate 0.01 % probeorbathorAbath16080253105AAs described in Test Method B430.BTween 2
23、1, chemically known as polyoxyethylene6sorbitan monolaurate, is manufactured by Croda International PLC, and is available from various chemical suppliers.CThree to five drops Tween 21 in 30 to 50 mL water.FIG. 1 General Dispersion ProcedureB821 1027.1.2.2 If the powder reacts with, or is soluble in,
24、 water, butnot organic liquids, select an appropriate organic liquid.7.1.2.3 If the powder is neither reactive nor soluble in water,select distilled or deionized water as the carrier liquid.7.1.3 Selection of SurfactantIf the powder is not wettableby the chosen carrier liquid, select a suitable surf
25、actant(dispersing agent).NOTE 2Ultrasonic energy treatment may be necessary to separateparticles so that the individual particles may be wetted by the carrier liquidor liquid/surfactant solution.NOTE 3Suggested surfactants are listed in Table 1 and footnotes 4through 6.4,5,67.1.3.1 The appropriate s
26、urfactant and its concentration aredetermined by trial and error; a series of concentrations ofdifferent candidate surfactants must be tried on separatesamples and the resultant particle size distribution analysescompared. The optimum surfactant and concentration areusually those that produce the fi
27、nest particle size distributionresults.NOTE 4Excess surfactant may cause a coarser particle size distribu-tion in the subsequent particle size analysis.7.1.4 Dispersion Check:7.1.4.1 Determine whether the powder is dispersed in theliquid by examining it carefully in a beaker during and afterstirring
28、. If the powder appears to be distributed uniformlythroughout the liquid, and does not flocculate within a fewseconds after the discontinuation of stirring, particle sizeanalysis can then be performed (9.1) and the results evaluated.7.1.4.2 Ultrasonic Energy TreatmentEven if the powderappears to be
29、uniformly dispersed, ultrasonic energy treatmentmay be necessary.NOTE 5Ultrasonic treatment may also be necessary to break upagglomerates in powders that appear to be dispersed, unless the agglom-erate distribution is desired from the subsequent analysis.7.1.4.3 Disperse the sample by placing the ca
30、rrier liquid/sample beaker in an ultrasonic bath or by inserting an ultra-sonic probe into the liquid/sample mixture. Continuous stirringof the liquid/sample mixture may be necessary through part orall of the ultrasonic treatment. As with surfactant selection(7.1.3.1), the appropriate time and power
31、 level for ultrasonictreatment must be determined by trial and error. Select the timeand power level by using the minimums necessary to ensureprecision and adequate dispersion, as determined in 7.1.4.1.The optimum ultrasonic treatment is usually that which pro-duces the finest particle size distribu
32、tion results without frac-turing the individual particles.NOTE 6Particle fracture can be evaluated by examining the treatedpowder in a suitable microscope and noting whether the particle shape ordistribution has changed significantly as the power level or treatment timehas been increased. Fracture o
33、f particles is also often indicated by a shiftfrom a unimodal to bimodal particle size distribution as the ultrasonicpower level or treatment time is increased.NOTE 7Some indication of the type of equipment, starting times, andpower levels for ultrasonic energy treatment may be obtained from Table1.
34、7.1.4.4 Check for dispersion, as in 7.1.4.1. If the powder isnow well-dispersed, continue with the particle size analysis(9.1).7.1.4.5 If the powder is still not well-dispersed after ultra-sonic energy treatment, select a different surfactant and repeatthe steps given in 7.1.3 and 7.1.4 (and their r
35、elevant subpara-graphs). Continue with this repetitive process until dispersionis attained.8. Recommended Dispersion Procedures8.1 Table 1 lists the dispersion procedures currently ingeneral use for several metals and metal compounds. Theseprocedures have been shown by experience to produce consis-t
36、ent, reproducible particle size analysis results for the materialslisted.9. Particle Size Distribution Analysis9.1 After dispersion has been achieved by one of the abovetechniques, immediately perform the required particle sizeanalysis by whatever method is applicable (for example, TestMethods B430,
37、 B761,orB822).10. Keywords10.1 liquid dispersion; metal powders; particle size analysis;powder metallurgySUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue(B821 02(2007) that may impact the use of this standard. (September 1, 2010.)(
38、1) Footnote 6 was once again modified to bring it up to datewith the current version of the reference document. Rationale:The earlier referenced document is no longer available, but anew version contains the pertinent information.(2) Footnote B in Table 1 was modified to reflect a change inthe sourc
39、e of Tween 21, based upon information availablethrough the internet. Rationale: The previous reference nolonger is correct based upon a search of the internet. It appearsthat either the product line was sold, or the company owningrights has undergone a name change.B821 103ASTM International takes no
40、 position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own respons
41、ibility.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 for revision of this standard or for additional standardsand should be addressed t
42、o ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the add
43、ress 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B821 104
