1、Designation: E2651 10E2651 13Standard 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. A number in parenthe
2、ses 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 techniques for particle size measurement and particle size distribution analysisof solid particulate (powder)
3、 materials. It does not apply to analysis of liquid droplets or liquid aerosols. The guide is intended toserve as a resource for powder/particle technologists in characterizing their materials.1.2 This guide provides more detail regarding the particle size analysis methods listed in Guide E1919, whi
4、ch is a compilationof worldwide published standards relating to particle and spray characterization. Although Guide E1919 and this guide are bothextensive, neither is all inclusive.1.3 The principle of operation, range of applicability, specific requirements (if any), and limitations of each of the
5、includedparticle size analysis techniques are listed and described, so that users of this guide may choose the most useful and most efficienttechnique for characterizing the particle size distribution of their particular material(s).1.4 The values stated in SI units are to be regarded as standard. N
6、o other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicabil
7、ity of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B215 Practices for Sampling Metal PowdersB330 Test Methods for Estimating Average Particle Size of Metal Powders and Related Compounds Using Air PermeabilityB821 Guide for Liquid Dispersion of Metal Powders and Rela
8、ted Compounds for Particle Size AnalysisB859 Practice for De-Agglomeration of Refractory Metal Powders and Their Compounds Prior to Particle Size AnalysisC322 Practice for Sampling Ceramic Whiteware ClaysE11 Specification for Woven Wire Test Sieve Cloth and Test SievesE1617 Practice for Reporting Pa
9、rticle Size Characterization DataE1638 Terminology Relating to Sieves, Sieving Methods, and Screening MediaE1919 Guide for Worldwide Published Standards Relating to Particle and Spray CharacterizationE2589 Terminology Relating to Nonsieving Methods of Powder Characterization3. Terminology3.1 Definit
10、ions:3.1.1 For definitions of terms used in this guide, refer to Terminologies E1638 and E2589.3.2 Definitions of Terms Specific to This Standard:3.2.1 powder, na collection of solid particles that are usually less than 1000 m (1 mm) in size.4. Significance and Use4.1 The myriad array of particle si
11、ze analysis techniques available to the modern-day powder technologist is both daunting andconfusing. Many of the techniques are applicable only to certain types of materials, and all have limited ranges of applicability1 This guide is under the jurisdiction of ASTM Committee E29 on Particle and Spr
12、ay Characterization and is the direct responsibility of Subcommittee E29.02 onNon-Sieving Methods.Current edition approved May 1, 2010Nov. 1, 2013. Published October 2010November 2013. Originally approved in 2008. Last previous edition approved in 20082010as E2651 08.E2651 10. DOI: 10.1520/E2651-10.
13、10.1520/E2651-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is
14、 intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the
15、current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1with respect to powder particle size. This guide is an attempt to describe and define the ap
16、plicability of each of the availabletechniques, so that powder technologists, and others interested in powders, may make informed and appropriate choices incharacterizing their materials.4.2 This guide is intended to be used to determine the best and most efficient way of characterizing the particle
17、 size distributionof a particular powder material. It may also be used to determine whether a reported powder particle size, or size distribution, wasobtained in an appropriate and meaningful way.4.3 Most particle size analysis techniques report particle size in terms of an “equivalent spherical dia
18、meter”:diameter:” thediameter of an ideal spherical particle of the material of interest that would be detected in the same manner during analysis as the(usually irregular-shaped) actual particle under the same conditions. The different techniques must necessarily use differentdefinitions of the equ
19、ivalent spherical diameter, based on their different operating principles. However, when analyzing elongatedparticles, the size parameter most relevant to the intended application should be measured; for example, length (maximumdimension).4.4 Reported particle size measurement is a function of both
20、the actual dimension and/or shape factor or shape factor, or both,as well as the particular physical or chemical properties of the particle being measured. Caution is required when comparing datafrom instruments operating on different physical or chemical parameters or with different particle size m
21、easurement ranges. Sampleacquisition, handling, and preparation can also affect reported particle size results.5. Reagents5.1 Purity of ReagentsReagent grade chemicals should be used in all tests. Unless otherwise indicated, it is intended that allreagents should conform to the specifications of the
22、 Committee onAnalytical Reagents of theAmerican Chemical Society.3 Othergrades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lesseningthe accuracy of the determination.5.2 SurfactantsSuitable surfactants are listed in referenc
23、es (1-3).46. Sampling6.1 The first step in performing a powder particle size analysis is obtaining a sample of the powder that is intended to berepresentative of the entire amount. There are two conditions necessary for obtaining an accurate sample of a powder (4): The firstis that the sampling must
24、 be probabilistic; that is, every increment of the powder must have some probability of being selected inthe sampling process. The sampling must not only be probabilistic, it must also be correct. That means that every sample incrementmust have an equal probability of being chosen. No method of samp
25、ling can guarantee a representative sample, but adherence tocertain “Golden Rules of Sampling” (1) will satisfy these two conditions and ensure a sample as close to representative as possible.These rules are:6.1.1 Always sample a powder in motion (for example, pouring from a blender, or off the end
26、of a conveyor).6.1.2 Take small portions for many short increments of time from the whole stream of powder.6.1.3 Never scoop a sample from a heap or container of powder.6.2 The preferred method of sampling is to use a spinning (rotary) riffler; however, this is not always possible. Devices thatadher
27、e to these rules, such as chute rifflers, spinning rifflers, and stream samplers, are available commercially. Examples of goodpowder sampling practices may be found in Practices B215 and C322.7. Dispersion7.1 The method of powder dispersion has a significant effect on the results of a particle size
28、distribution analysis. The analysiswill show a too-coarse, unstable, or non-repeatable distribution if the powder has not been dispersed adequately. It is thereforeimportant that parties wishing to compare their analyses use the same dispersion technique.7.2 Many particle size analysis instruments a
29、re capable of, or require, dispersing powders in a liquid medium. Guide B821contains recommended liquid dispersion procedures for certain metal powders and related compounds. That guide also containsgeneral procedures for dispersing powders in liquids, and assessing dispersion. Those general procedu
30、res are repeated here:7.3 The general procedure for determining and achieving proper dispersion is outlined in Fig. 1 (5) and described in detailbelow:7.3.1 Place a test portion of the powder to be analyzed in a beaker containing the carrier liquid, selected according to 7.3.2.7.3.2 Selection of Car
31、rier Liquid:NOTE 1The selected carrier liquid must be compatible with the components of the instrument used for the particle size analysis.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC, www.chemistry.org. For suggestions on the testing ofrea
32、gents not listed by theAmerican Chemical Society, see the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD, http:/www.usp.org.4 The boldface numbers in parentheses refer to the list of references at the end of this standard.E2651 1327.3.2.1
33、If the powder reacts with, or is soluble in, water and organic liquids, it must be analyzed in the dry state. Some particlesize analysis instruments have built-in systems for de-agglomerating and dispersing dry powders. Consult the instrumentmanufacturers operating manual. See 7.4 for further guidan
34、ce on dry dispersion.7.3.2.2 If the powder reacts with, or is soluble in, water, but not 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
35、 powder is not wettable by the chosen carrier liquid, select a suitable surfactant (dispersingagent).NOTE 2Ultrasonic energy treatment may be necessary to separate particles so that the individual particles may be wetted by the carrier liquid orliquid/surfactant solution.NOTE 3Suitable surfactants a
36、re listed in references (1-3).7.3.3.1 The appropriate surfactant and its concentration are determined by trial and error; a series of concentrations of differentcandidate surfactants must be tried on separate samples and the resultant particle size distribution analyses compared.The optimumsurfactan
37、t and concentration are usually those that produce the finest particle size distribution results.NOTE 4Excess surfactant may cause a coarser particle size distribution in the subsequent particle size analysis.FIG. 1 General Dispersion Procedure (5)E2651 1337.3.4 Dispersion Check:7.3.4.1 Determine wh
38、ether the powder is dispersed in the liquid by examining it carefully in a beaker during and after stirring.If the powder appears to be distributed uniformly throughout the liquid, and does not flocculate within a few seconds after thediscontinuation of stirring, particle size analysis can then be p
39、erformed and the results evaluated. In addition, the use of opticalmicroscopy to directly observe the state of dispersion is recommended.7.3.4.2 Ultrasonic Energy TreatmentEven if the powder appears to be uniformly dispersed, ultrasonic energy treatment maybe necessary.NOTE 5Ultrasonic treatment may
40、 also be necessary to break up agglomerates in powders that appear to be dispersed, unless the agglomeratedistribution is desired from the subsequent analysis.7.3.4.3 Disperse the sample by placing the carrier liquid/sample beaker in an ultrasonic bath or by inserting an ultrasonic probeinto the liq
41、uid/sample mixture. Continuous stirring of the liquid/sample mixture may be necessary through part or all of theultrasonic treatment. As with surfactant selection (7.3.3.1), the appropriate time and power level for ultrasonic treatment must bedetermined by trial and error. Select the time and power
42、level by using the minimums necessary to ensure precision and adequatedispersion, as determined in 7.3.4.1. The optimum ultrasonic treatment is usually that which produces the finest particle sizedistribution results without fracturing the individual particles.NOTE 6Particle fracture can be evaluate
43、d by examining the treated powder with a suitable microscope and noting whether the particle shape ordistribution has changed significantly as the power level or treatment time has been increased. Fracture of particles is also often indicated by a shift froma unimodal to bimodal particle size distri
44、bution as the ultrasonic power level or treatment time is increased.NOTE 7Some indication of the type of equipment, starting times, and power levels for ultrasonic energy treatment may be obtained from Table 1 inGuide B821.7.3.4.4 Check for dispersion, as in 7.3.4.1. If the powder is now well-disper
45、sed, continue with the particle size analysis.7.3.4.5 If the powder is still not well-dispersed after ultrasonic energy treatment, select a different surfactant, or combinationof surfactants, and repeat the steps given in 7.3.3 and 7.3.4 (and their relevant subparagraphs). Continue with this repetit
46、ive processuntil 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(see 7.3.2.1).7.4.1 Many dry dispersion units are based on vacuum or pressurized ga
47、s flow, or both. The generated gas flow sprays theparticles inside a closed chamber or through an adjustable orifice, and they fall back on suitable media like microscope glass slides,or are directly introduced into the instruments measurement zone. The user should adjust the units parameters to obt
48、ain a gooddispersion, with a minimum of agglomerates, and without damaging the particles. The gas flow path, the pressure difference, andthe gas release interval are examples of variables that should be adjusted by consulting the manufacturers guide.PARTICLE SIZE ANALYSIS TECHNIQUES8. Sieving8.1 Pri
49、nciple of OperationSieving consists of passing a powder through a screen (sieve) with a specified opening size andmeasuring, by weighing, the amount of powder either remaining on the sieve or passing through. A particle size distribution maybe obtained by stacking sieves of increasing opening size and measuring the amount collected on each sieve.8.2 Particle Size Range of ApplicationAlthough sieves are available with aperture sizes down to about 5 m, the practicallower limit for sieve analysis is usually considered to be 38 m (400 mesh).At the upper end,
