1、Designation: E2651 10An American National StandardStandard Guide forPowder Particle Size Analysis1This standard is issued under the fixed designation E2651; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the use of many available techniquesfor particle size measurement and particle size distributionanalysis of solid
3、particulate (powder) materials. It does notapply to analysis of liquid droplets or liquid aerosols. Theguide is intended to serve as a resource for powder/particletechnologists in characterizing their materials.1.2 This guide provides more detail regarding the particlesize analysis methods listed in
4、 Guide E1919, which is acompilation of worldwide published standards relating toparticle and spray characterization.Although Guide E1919 andthis guide are both extensive, neither is all inclusive.1.3 The principle of operation, range of applicability, spe-cific requirements (if any), and limitations
5、 of each of theincluded particle size analysis techniques are listed and de-scribed, so that users of this guide may choose the most usefuland most efficient technique for characterizing the particle sizedistribution of their particular material(s).1.4 The values stated in SI units are to be regarde
6、d asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not 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
7、the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B215 Practices for Sampling Metal PowdersB821 Guide for Liquid Dispersion of Metal Powders andRelated Compounds for Particle Size AnalysisC322 Practice for Sampling Ceramic Whiteware ClaysE11 Specifi
8、cation for Woven Wire Test Sieve Cloth and TestSievesE1617 Practice for Reporting Particle Size CharacterizationDataE1638 Terminology Relating to Sieves, Sieving Methodsand Screening MediaE1919 Guide for Worldwide Published Standards Relatingto Particle and Spray CharacterizationE2589 Terminology Re
9、lating to Nonsieving Methods ofPowder Characterization3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this guide, refer toTerminologies E1638 and E2589.3.2 Definitions of Terms Specific to This Standard:3.2.1 powder, na collection of solid particles that areusually less than 100
10、0 m (1 mm) in size.4. Significance and Use4.1 The myriad array of particle size analysis techniquesavailable to the modern-day powder technologist is bothdaunting and confusing. Many of the techniques are applicableonly to certain types of materials, and all have limited rangesof applicability with
11、respect to powder particle size. This guideis an attempt to describe and define the applicability of each ofthe available techniques, so that powder technologists, andothers interested in powders, may make informed and appro-priate choices in characterizing their materials.4.2 This guide is intended
12、 to be used to determine the bestand most efficient way of characterizing the particle sizedistribution of a particular powder material. It may also be usedto determine whether a reported powder particle size, or sizedistribution, was obtained in an appropriate and meaningfulway.4.3 Most particle si
13、ze analysis techniques report particlesize in terms of an “equivalent spherical diameter”: thediameter of an ideal spherical particle of the material of interestthat would be detected in the same manner during analysis asthe (usually irregular-shaped) actual particle under the sameconditions. The di
14、fferent techniques must necessarily usedifferent definitions of the equivalent spherical diameter, basedon their different operating principles. However, when analyz-ing elongated particles, the size parameter most relevant to theintended application should be measured; for example, length(maximum d
15、imension).1This guide is under the jurisdiction of ASTM Committee E29 on Particle andSpray Characterization and is the direct responsibility of Subcommittee E29.02 onNon-Sieving Methods.Current edition approved May 1, 2010. Published October 2010. Originallyapproved in 2008. Last previous edition ap
16、proved in 2008 as E2651 08. DOI:10.1520/E2651-10.2For 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 Document Summary page onthe ASTM website.1Copyright A
17、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 Reported particle size measurement is a function of boththe actual dimension and/or shape factor as well as theparticular physical or chemical properties of the particle beingmeasured. Caution
18、is required when comparing data frominstruments operating on different physical or chemical param-eters or with different particle size measurement ranges.Sample acquisition, handling, and preparation can also affectreported particle size results.5. Reagents5.1 Purity of ReagentsReagent grade chemic
19、als should beused in all tests. Unless otherwise indicated, it is intended thatall reagents should conform to the specifications 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
20、purity topermit its use without lessening the accuracy of the determi-nation.5.2 SurfactantsSuitable surfactants are listed in refer-ences (1-3).46. Sampling6.1 The first step in performing a powder particle sizeanalysis is obtaining a sample of the powder that is intended tobe representative of the
21、 entire amount. There are two condi-tions necessary for obtaining an accurate sample of a powder(4): The first is that the sampling must be probabilistic; that is,every increment of the powder must have some probability ofbeing selected in the sampling process. The sampling must notonly be probabili
22、stic, it must also be correct. That means thatevery sample increment must have an equal probability ofbeing chosen. No method of sampling can guarantee a repre-sentative sample, but adherence to certain “Golden Rules ofSampling” (1) will satisfy these two conditions and ensure asample as close to re
23、presentative as possible. These rules are:6.1.1 Always sample a powder in motion (for example,pouring from a blender, or off the end of a conveyor).6.1.2 Take small portions for many short increments of timefrom the whole stream of powder.6.1.3 Never scoop a sample from a heap or container ofpowder.
24、6.2 The preferred method of sampling is to use a spinning(rotary) riffler; however, this is not always possible. Devicesthat adhere to these rules, such as chute rifflers, spinningrifflers, and stream samplers, are available commercially.Examples of good powder sampling practices may be found inPrac
25、tices B215 and C322.7. Dispersion7.1 The method of powder dispersion has a significant effecton the results of a particle size distribution analysis. Theanalysis will show a too-coarse, unstable, or non-repeatabledistribution if the powder has not been dispersed adequately. Itis therefore important
26、that parties wishing to compare theiranalyses use the same dispersion technique.7.2 Many particle size analysis instruments are capable of,or require, dispersing powders in a liquid medium. Guide B821contains recommended liquid dispersion procedures for certainmetal powders and related compounds. Th
27、at guide also con-tains general procedures for dispersing powders in liquids, andassessing dispersion. Those general procedures are repeatedhere:7.3 The general procedure for determining and achievingproper dispersion is outlined in Fig. 1 (5) and described indetail below:7.3.1 Place a test portion
28、of the powder to be analyzed in abeaker containing the carrier liquid, selected according to7.3.2.7.3.2 Selection of Carrier Liquid:NOTE 1The selected carrier liquid must be compatible with thecomponents of the instrument used for the particle size analysis.7.3.2.1 If the powder reacts with, or is s
29、oluble in, water andorganic liquids, it must be analyzed in the dry state. Someparticle size analysis instruments have built-in systems forde-agglomerating and dispersing dry powders. Consult theinstrument manufacturers operating manual. See 7.4 for fur-ther guidance on dry dispersion.7.3.2.2 If the
30、 powder reacts with, or is soluble in, water, butnot organic liquids, select an appropriate organic liquid.7.3.2.3 If the powder is neither reactive nor soluble in water,select distilled or deionized water as the carrier liquid.7.3.3 Selection of SurfactantIf the powder is not wettableby the chosen
31、carrier liquid, select a suitable surfactant(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 3Suitable surfactants are listed in references (1-3).7.3.3.1 T
32、he appropriate surfactant 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 tha
33、t produce the finest particle size distributionresults.NOTE 4Excess surfactant may cause a coarser particle size distribu-tion in the subsequent particle size analysis.7.3.4 Dispersion Check:7.3.4.1 Determine whether the powder is dispersed in theliquid by examining it carefully in a beaker during a
34、nd afterstirring. 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 and the results evaluated. Inaddition, the use of optical microscopy to directly ob
35、serve thestate of dispersion is recommended.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC, www.chemistry.org. For suggestions on thetesting of reagents not listed by the American Chemical Society, see the UnitedStates Pharmacopeia and National
36、 Formulary, U.S. Pharmacopeial Convention,Inc. (USPC), Rockville, MD, http:/www.usp.org.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.E2651 1027.3.4.2 Ultrasonic Energy TreatmentEven if the powderappears to be uniformly dispersed, ultrasonic energy t
37、reatmentmay 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.7.3.4.3 Disperse the sample by placing the carrier liquid/sample beaker in an ultraso
38、nic 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(7.3.3.1), the appropriate time and power level for ultrasonictreatment must be d
39、etermined by trial and error. Select the timeand power level by using the minimums necessary to ensureprecision and adequate dispersion, as determined in 7.3.4.1.The optimum ultrasonic treatment is usually that which pro-duces the finest particle size distribution results without frac-turing the ind
40、ividual particles.NOTE 6Particle fracture can be evaluated by examining the treatedpowder with a suitable microscope and noting whether the particle shapeor distribution has changed significantly as the power level or treatmenttime has been increased. Fracture of particles is also often indicated by
41、 ashift from 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 Table 1in Guide B821.7.3.4.4 Check for disper
42、sion, as in 7.3.4.1. If the powder isnow well-dispersed, continue with the particle size analysis.7.3.4.5 If the powder is still not well-dispersed after ultra-sonic energy treatment, select a different surfactant, or combi-nation of surfactants, and repeat the steps given in 7.3.3 and7.3.4 (and the
43、ir relevant subparagraphs). Continue with thisrepetitive process until dispersion is attained.7.4 Dry dispersion is sometimes preferred to wet dispersion,especially when working with static image analysis techniques.Sometimes, dry dispersion is the only alternative (See 7.3.2.1).7.4.1 Many dry dispe
44、rsion units are based on vacuum orpressurized gas flow, or both. The generated gas flow spraysthe particles inside a closed chamber or through an adjustableorifice, and they fall back on suitable media like microscopeglass slides, or are directly introduced into the instrumentsmeasurement zone. The
45、user should adjust the units param-eters to obtain a good dispersion, with a minimum of agglom-erates, and without damaging the particles. The gas flow path,the pressure difference, and the gas release interval are ex-amples of variables that should be adjusted by consulting themanufacturers guide.P
46、ARTICLE SIZE ANALYSIS TECHNIQUES8. Sieving8.1 Principle of OperationSieving consists of passing apowder through a screen (sieve) with a specified opening sizeFIG. 1 General Dispersion Procedure (5)E2651 103and measuring, by weighing, the amount of powder eitherremaining on the sieve or passing throu
47、gh. A particle sizedistribution may be obtained by stacking sieves of increasingopening size and measuring the amount collected on eachsieve.8.2 Particle Size Range of ApplicationAlthough sievesare available with aperture sizes down to about 5 m, thepractical lower limit for sieve analysis is usuall
48、y considered tobe 38 m (400 mesh). At the upper end, Specification E11specifies aperture sizes and tolerances for sieve openings up to125 mm.8.3 Specific RequirementsBecause there are many waysof agitating sieves (sieve shakers, ultrasonics, etc.), the methodof agitation and the duration of agitatio
49、n must be standardized.Guidelines for establishing sieve analysis procedures can befound in the Manual on Test Sieving Methods (6).8.4 Limitations:8.4.1 A relatively large sample, 50 to 100 g, is usuallyrequired for an accurate measurement of the mass of powderretained on each sieve.8.4.2 Information about the largest and smallest particles inthe powder is not available, only that they are larger than, orsmaller than, a specified size.9. Sedimentation9.1 Principle of OperationSedimentation analysis isbased on Stokes Law (7), which mathematically states that
