1、Designation: B 761 06Standard Test Method forParticle Size Distribution of Metal Powders and RelatedCompounds by X-Ray Monitoring of Gravity Sedimentation1This standard is issued under the fixed designation B 761; the number immediately following the designation indicates the year oforiginal adoptio
2、n or, in the case of 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. Scope*1.1 This test method covers the determination of particlesize distributions o
3、f metal powders. Experience has shown thatthis test method is satisfactory for the analysis of elementaltungsten, tungsten carbide, molybdenum, and tantalum pow-ders, all with an as-supplied Fisher number of 6 m or less, asdetermined by Test Method B 330. Other metal powders (forexample, elemental m
4、etals, carbides, and nitrides) may beanalyzed using this test method with caution as to significanceuntil actual satisfactory experience is developed (see 7.2). Theprocedure covers the determination of particle size distributionof the powder in the following two conditions:1.1.1 As the powder is sup
5、plied (as-supplied), and1.1.2 After the powder has been deagglomerated by rodmilling as described in Practice B 859.1.2 This test method is applicable to particles of uniformdensity and composition having a particle size distributionrange of 0.1 up to 100 m.1.2.1 However, the relationship between si
6、ze and sedimen-tation velocity used in this test method assumes that particlessediment within the laminar flow regime. This requires that theparticles sediment with a Reynolds number of 0.3 or less.Particle size distribution analysis for particles settling with alarger Reynolds number may be incorre
7、ct due to turbulent flow.Some materials covered by this test method may settle withReynolds number greater than 0.3 if particles greater than 25m are present. The user of this test method should calculatethe Reynolds number of the largest particle expected to bepresent in order to judge the quality
8、of obtained results.Reynolds number (Re) can be calculated using the flowingequationRe 5D3r r0!r0g18h2(1)whereD = the diameter of the largest particle expected to bepresent,r = the particle density,r0= the suspending liquid density,g = the acceleration due to gravity, andh = is the suspending liquid
9、 viscosity.A table of the largest particles that can be analyzed withReynolds number of 0.3 or less in water at 35C is given for anumber of metals in Table 1.Acolumn of the Reynolds numbercalculated for a 30m particle sedimenting in the same liquidsystem is given for each material also.1.3 This stan
10、dard 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 the applica-bility of regulatory limitations prior to use. Specific hazardinformation
11、is given in Section 7.2. Referenced Documents2.1 ASTM Standards:2B 330 Test Method for Fisher Number of Metal Powdersand Related CompoundsB 821 Guide for Liquid Dispersion of Metal Powders andRelated Compounds for Particle Size AnalysisB 859 Practice for De-Agglomeration of Refractory MetalPowders a
12、nd Their Compounds Prior to Particle SizeAnalysisE 456 Terminology Relating to Quality and StatisticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 A carefully dispersed homogeneous suspension of thepowder is permitted to
13、 settle in a cell scanned by a collimatedX-ray beam of constant intensity. The net X-ray signal is1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.03 on Refractory Metal Powders.Current e
14、dition approved April 1, 2006. Published May 2006. Originallyapproved in 1986. Last previous edition approved in 2002 as B 761 02e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inform
15、ation, refer to the standards Document 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.inversely proportional to the sample concentrati
16、on in thedispersing medium, and the particle diameter is related to theposition of the X-ray beam relative to the top of the cell.Cumulative mass percent versus equivalent spherical diameterare recorded to yield a particle size distribution curve.4. Significance and Use4.1 This test method is useful
17、 to both suppliers and users ofpowders, as outlined in 1.1 and 1.2, in determining particle sizedistribution for product specifications, manufacturing control,development, and research.4.2 Users should be aware that sample concentrations usedin this test method may not be what is considered ideal by
18、 someauthorities, and that the range of this test method extends intothe region where Brownian movement could be a factor inconventional sedimentation. Within the range of this testmethod, neither the sample concentration nor Brownian move-ment are believed to be significant.4.3 Reported particle si
19、ze measurement is a function of boththe actual particle dimension and shape factor as well as theparticular physical or chemical properties being measured.Caution is required when comparing data from instrumentsoperating on different physical or chemical parameters or withdifferent particle size mea
20、surement ranges. Sample acquisition,handling, and preparation can also affect reported particle sizeresults.5. Apparatus5.1 Gravitational sedimentation particle size analyzer utiliz-ing X-ray extinction to determine particle concentration.36. Reagents and Materials6.1 Purity of ReagentsReagent grade
21、 chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided it is first ascertained th
22、at the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Dispersing MediumDissolve 0.10 g of sodium hex-ametaphosphate (NaPO3)6 in 1000 mL of distilled or deion-ized water.6.3 Cleaning SolutionDissolve 0.5 g of laboratory deter-gent in 100
23、0 mL of distilled or deionized water, or prepare a0.1 % solution by volume of Triton X-100 using distilled ordeionized water.57. Hazards7.1 Precautions applying to the use of low intensity X-rayunits should be observed.7.2 Most carbides and nitrides are brittle materials and maybe partially deagglom
24、erated or fractured, or both, during themanufacturing process. Different manufacturing processes orchanges in the process may affect the apparent particle sizedistribution as determined by this test method. Thus, cautionshould be used in evaluating the results, especially for brittlematerials.8. Sam
25、ple Preparation8.1 For the as-supplied particle size distribution determina-tions, this step is not needed.8.2 For laboratory-milled particle size distribution determi-nations, use the rod milling technique as outlined in PracticeB 859.9. Procedure9.1 See the manufacturers manual for general operati
26、nginstructions.9.2 Set up the instrument in the “percent finer than” mode ifnecessary. Ensure proper operating conditions by periodicallyperforming base line scan and beam split test if necessary.3The sole instrument of this type known to the committee as this time is theSediGraph X-ray gravity sedi
27、mentation particle size analyzer, available fromMicromeritics Instrument Corporation, 1 Micromeritics Drive, Norcross, GA30093.If you are aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of
28、 the responsible technical committee,1which you may attend.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH
29、Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.5Triton X-100 is a trademarked product of Rohm six or more recommended), the user of this testmethod may infer its precision from this interlaboratory study.T
30、he pertinent conclusions are presented below:11.1.1 The within-laboratory repeatability limit, r, for themedian particle size (r as defined by Terminology E 456), wasfound to be estimated by the following equation:r 5 0.133M 0.009 (2)whereM = the measured median particle size (m), in the range of1.4
31、 to 4.2 m (r = 0.15 to 0.55 m in this range).Duplicate median particle size results from the same laboratoryshould not be considered suspect unless they differ by morethan r.11.1.2 The between-laboratory reproducibility limit, R, forthe median particle size (R as defined by Terminology E 456)was fou
32、nd to be estimated by the following equation:R 5 0.482M 0.489 (3)whereM = the measured median particle size (m) in the range of1.4 to 4.2 m (R = 0.19 to 1.54 m in this range).Median particle size results from two different laboratoriesshould not be considered suspect unless they differ by morethan R
33、.11.2 BiasNo absolute method of determining powderparticle size exists, nor are there any universally recognizedstandard or reference powders for this measurement. There-fore, it is not possible to discuss the bias results by this testmethod.12. Keywords12.1 metal powders; particle size; particle si
34、ze distribution;powdered metals; refractory metal powders; sedimentationparticle size distribution6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: B091011.TABLE 2 Suggested Approximate Starting Weights for Tungstenor Tungsten Ca
35、rbideNominal Fisher Number Accordingto Test Method B 330 of As-Supplied Powder, mWeightA, g per 25 mL ofDispersing Medium1 0.212 0.233 0.264 0.285 0.306 0.33AThe amount of sample required will vary. Increase or decrease the sampleweight as needed to provide the level of X-ray attenuation recommended
36、 inanalyzer instruction manual.B761063SUMMARY OF CHANGESCommittee B09 has identified the location of selected changes to this standard since the last issue,B76102e1, that may impact the use of this standard. (Approved April 1, 2006.)(1) A footnote containing sole source information for appara-tus me
37、eting specifications of this test method was inserted.Rationale: The subcommittee is only aware of one source ofcommercial apparatus.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standar
38、d 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
39、not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, whic
40、h 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 address 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).B761064
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