1、Designation: B 822 02Standard Test Method forParticle Size Distribution of Metal Powders and RelatedCompounds by Light Scattering1This standard is issued under the fixed designation B 822; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, 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 by light scattering, rep
3、orted as volume per-cent, of particulate materials including metals and compounds.1.2 This test method applies to analyses with both aqueousand nonaqueous dispersions. In addition, analysis can beperformed with a gaseous dispersion for materials that arehygroscopic or react with a liquid carrier.1.3
4、 This test method is applicable to the measurement ofparticulate materials in the range of 0.4 to 2000 m, or a subsetof that range, as applicable to the particle size distributionbeing measured.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to
5、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:B 215 Pract
6、ices for Sampling Finished Lots of Metal Pow-ders2B 243 Terminology of Powder Metallurgy2B 821 Guide for Liquid Dispersion of Metal Powders andRelated Compounds for Particle Size Analysis2E 1617 Practice for Reporting Particle Size Characteriza-tion Data32.2 ISO Standard4:ISO13320-1 Particle Size An
7、alysisLaser DiffractionMethodsPart 1: General Principles3. Terminology3.1 DefinitionsDefinitions of powder metallurgy termscan be found in Terminology B 243.3.2 Definitions of Terms Specific to This Standard:3.2.1 backgroundextraneous scattering of light by ele-ments other than the particles to be m
8、easured; includesscattering by contamination in the measurement path.3.2.2 Fraunhofer Diffractionthe optical theory that de-scribes the low-angle scattering of light by particles that arelarge compared to the wavelength of the incident light.53.2.3 Mie Scatteringthe complex electromagnetic theorytha
9、t describes the scattering of light by spherical particles. It isusually applied to particles with diameters that are close to thewavelength of the incident light. The real and imaginaryindices of light refraction of the particles are needed.53.2.4 multiple scatteringthe rescattering of light by apa
10、rticle in the path of light scattered by another particle. Thisusually occurs in heavy concentrations of a particle dispersion.4. Summary of Test Method4.1 A prepared sample of particulate material is dispersed inwater, or a compatible organic liquid, and circulated throughthe path of a light beam o
11、r some other suitable light source. Adry sample may be aspirated through the light in a carrier gas.The particles pass through the light beam and scatter it.Photodetector arrays collect the scattered light that is convertedto electrical signals, which are then analyzed in a micropro-cessor. The sign
12、al is converted to a size distribution usingFraunhofer Diffraction or Mie Scattering, or a combination ofboth. Scattering information is analyzed assuming a sphericalmodel. Calculated particle sizes are therefore presented asequivalent spherical diameters. Additional information pertain-ing to the g
13、eneral principles of particle size distributionanalysis by light scattering can be found in ISO Standard13320-1.5. Significance and Use5.1 Reported particle size measurement is a function of boththe actual particle dimension and shape factor as well as theparticular physical or chemical properties b
14、eing measured.Caution is required when comparing data from instrumentsoperating on different physical or chemical parameters or with1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Productsand is the direct responsibility of Subcommit-tee B09.02on Ba
15、se Metal Powders.Current edition approved April 10, 2002. Published June 2002. Originallypublished as B 822 92. Last previous edition B 822 97.2Annual Book of ASTM Standards, Vol 02.05.3Annual Book of ASTM Standards Vol 14.02.4Available from American National Standards Institute, 11 W. 42ndSt., 13th
16、Floor, New York, NY 10036.5Muly, E. C., Frock, H. N., “Industrial Particle Size Measurement Using LightScattering,” Optical Engineering, Vol 19, No 6, 1980, pp. 861869.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.different particl
17、e size measurement ranges. Sample acquisition,handling, and preparation can also affect reported particle sizeresults.5.1.1 It is important to recognize that the results obtained bythis test method, or any other method for particle size deter-mination using different physical principles, may disagre
18、e. Theresults are strongly influenced by the physical principlesemployed by each method of particle size analysis. The resultsof any particle sizing method should be used only in a relativesense; they should not be regarded as absolute when comparingresults obtained by other methods.5.2 Light scatte
19、ring theory has been available for manyyears for use in the determination of particle size. Severalmanufacturers of testing equipment now have units based onthese principles. Although each type of testing equipment usesthe same basic principles for light scattering as a function ofparticle size, dif
20、ferent assumptions pertinent to application ofthe theory, and different models for converting light measure-ments to particle size, may lead to different results for eachinstrument. Therefore, the use of this test method cannotguarantee directly comparable results from different types ofinstruments.
21、5.3 Knowledge of the particle size distribution of metalpowders is useful in predicting the powder-processing behaviorand ultimate performance of powder metallurgy parts. Particlesize distribution is related closely to the flowability, moldabil-ity, compressibility, and die-filling characteristics o
22、f a powder,as well as to the final structure and properties of finishedpowder metallurgy (P/M) parts.5.4 This test method is useful to both suppliers and users ofpowders in determining the particle size distributions forproduct specifications, manufacturing control, development,and research.5.5 This
23、 test method may be used to obtain data forcomparison between lots of the same material or for establish-ing conformance, as in acceptance testing.6. Interferences6.1 Air bubbles entrained in the circulating fluid will scatterlight and then be reported as particles. Circulating fluids maynot require
24、 degassing, but they should be bubble-free uponvisual inspection.6.2 Contaminants, such as nonaqueous solvents, oil, orother organic coatings on the sample, may emulsify in anaqueous carrier, scatter light, and thus be reported as part of theparticle size distribution. Samples containing such contam
25、i-nants may be analyzed in a nonaqueous carrier solvent todissolve the contaminant, or they may be washed free of thecontaminant with a compatible aqueous solvent.6.3 The presence of oil, water, or foreign substances in agaseous dispersion will cause clogging or agglomeration orwill bias the particl
26、e size results. The gas supplied should befree of these substances.6.4 Reagglomeration or settling of particulates duringanalysis will cause erroneous results. Dispersions shall beprepared in accordance with Guide B 821, and a stabledispersion shall be maintained throughout the analysis.6.5 Insuffic
27、ient sample loading may cause electrical noiseinterference and poor data repeatability. Excessive sampleloading may cause excessive light attenuation and multiplescattering, resulting in erroneous particle size distributions.7. Apparatus7.1 Particle Size Analyzer, based on Fraunhofer Diffractionor M
28、ie Scattering, or a combination of both light scatteringanalysis techniques. Care must be taken to ensure that theanalyzer system or subsystem is optimum for the size range ofthe powder being tested.7.2 Liquid or Gaseous Sample Handling System.8. Reagents and Materials8.1 Purity of ReagentsReagent g
29、rade 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 Chemical Society.6Other grades may be used, provided it is first ascertained thatthe reagent is of suffic
30、iently high purity to permit its usewithout lessening the accuracy of the determination.8.2 Appropriate Application-Specific Carrier, as determinedby Guide B 821. The carrier shall meet the following condi-tions:8.2.1 It shall be chemically compatible with the construc-tion material of the sample de
31、livery system,8.2.2 It shall not cause dissolution of the particles, and8.2.3 It shall be sufficiently clean and non-absorbing toachieve acceptable background levels.8.3 Antifoaming Agent, or equivalent.8.4 Dry, Clean Gas, for gaseous dispersions.8.5 Appropriate Surfactant, as determined by Guide B
32、821,subject to the conditions listed in 8.2.9. Sampling and Sample Size9.1 Obtain a test sample according to Practices B 215. Thetest portion shall be extracted from the test sample using amicrosample splitter; quartering shall not be used.9.2 The maximum test sample for liquid dispersion will beno
33、more than 25 g. No more than 500 g will be needed for agaseous dispersion.10. Calibration and Standardization10.1 Performance of the instrument is defined by the spac-ing and position of the optical components (refer to theinstruction manual provided by the manufacturer).10.2 No absolute standards a
34、re available for particle sizeanalysis. Diagnostic powders should be available from theequipment manufacturer to ensure consistent instrument func-tioning.11. Procedure11.1 Allow the instrument to warm up for a minimum of 20min.6Reagent Chemicals, American Chemical Society Specifications, AmericanCh
35、emical 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), Ro
36、ckville,MD.B 822211.2 Install the desired sample delivery system and selectthe applicable instrument range, as indicated by the instruc-tions provided by the instrument manufacturer.11.3 Establish correct optical alignment, if necessary, ac-cording to the requirements of the manufacturer.NOTE 1Optic
37、al alignment should be checked upon startup, wheneverthe sample delivery system is changed, or at least once a day.11.4 Measure the background in the mode in which theanalysis will be conducted. Be sure that the carrier is flowingthrough the light path while measuring background. Back-ground values
38、shall not exceed the specifications of themanufacturer. If background values exceed the recommenda-tions of the manufacturer, perform the necessary procedures asspecified by the manufacturer to bring the background valuesto within acceptable limits.11.5 Obtain a representative test sample according
39、to Prac-tices B 215. Extract a test portion from the test sample using amicrosample splitter. Refer to the recommendations of theequipment manufacturer to ensure that the amount of the testportion is acceptable to achieve optimum light scatteringconditions. A wide range of sample sizes is acceptable
40、,depending on median particle size (50 %), particle density(mass/volume), and sample delivery system.11.6 Select the appropriate run time for the sample. Thisprocedure is very specific to the application and is generallygaged by the run-to-run repeatability.11.7 Select the desired data output parame
41、ters, according tothe requirements set forth by the instrument manufacturer.11.8 For liquid dispersions, disperse the test portion accord-ing to the procedure outlined in Guide B 821. Gaseous disper-sions require no additional sample preparation.11.9 Transfer the prepared sample directly to the samp
42、ledelivery system. In the liquid system, allow circulation for 20s before measuring. In the dry sampling system, engage thesample switch to allow the sample to begin to flow into thelight source before starting measurement.11.10 Perform the sample analysis according to the instruc-tions of the manuf
43、acturer.11.11 In the liquid system, drain and fill the sample disper-sion system in preparation for the next sample analysis. Drainand rinse as necessary, to achieve background values withinacceptable operating limits, as specified by the manufacturer.NOTE 2When changing from either polar to a nonpo
44、lar organic liquidor nonpolar to polar liquid, it will be necessary to rinse the sampledelivery system several times with a compatible solvent, such as alcohol,to eliminate the formation of an interference emulsion due to crosscontamination of the two carriers.11.12 In the dry gaseous system, brush
45、or vacuum out allparticles throughout the sample system. Purge with air toremove particles remaining in the sample delivery system.11.13 Repeat Steps 11.5 through 11.11 for additional testportion analyses.12. Report12.1 Practice E 1617 specifies three detail levels for report-ing particle size chara
46、cterization data. It is up to the supplierand the user of the data to determine which level of reportingis needed. As a minimum, report the following information:12.1.1 The instrument name and model number used andthe range selected,12.1.2 The method of dispersing the test portion,12.1.3 The instrum
47、ent analysis run time,12.1.4 Any curve fit models used (where applicable),12.1.5 The real and imaginary refractive index of the samplematerial (where applicable),12.1.6 The real refractive index of the dispersing liquid,12.1.7 The volume mean diameter,12.1.8 The differential volume percent versus di
48、ameter, and12.1.9 The cumulative volume percent versus diameter.13. Precision and Bias13.1 No statement can be made concerning the precisionand bias of this test method at this time. An interlaboratorystudy is underway.14. Keywords14.1 laser diffraction; light scattering; metal powders; par-ticle si
49、ze distribution; powder metallurgyASTM International takes no 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 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
