ASTM_B_761_-_06_2011.pdf

Designation:B76106(Reapproved 2011)Standard Test Method forParticle Size Distribution of Metal Powders and RelatedCompounds by X-Ray Monitoring of Gravity Sedimentation1This standard is issued under the fixed designation B761;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 parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the determination of particlesize distributions of metal powders.Experience has shown thatthis test method is satisfactory for the analysis of elementaltungsten,tungsten carbide,molybdenum,and tantalumpowders,all with an as-supplied Fisher number of 6 m or less,as determined by Test Method B330.Other metal powders(forexample,elemental metals,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 supplied(as-supplied),and1.1.2 After the powder has been deagglomerated by rodmilling as described in Practice B859.1.2 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 size 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 incorrect 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 of obtained results.Reynolds number(Re)can be calculated using the flowingequationRe5D3 2 0!0g182(1)whereD=the diameter of the largest particle expected to bepresent,=the particle density,0=the suspending liquid density,g=the acceleration due to gravity,and=is the suspending liquid 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 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 the applica-bility of regulatory limitations prior to use.Specific hazardinformation is given in Section 7.2.Referenced Documents2.1 ASTM Standards:2B330 Test Methods for Estimating Average Particle Size ofMetal Powders and Related Compounds Using Air Per-meabilityB821 Guide for Liquid Dispersion of Metal Powders andRelated Compounds for Particle Size AnalysisB859 Practice for De-Agglomeration of Refractory MetalPowders and Their Compounds Prior to Particle SizeAnalysisE456 Terminology Relating to Quality and StatisticsE691 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 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 Productsand is the direct responsibility of Subcommit-tee B09.03 on Refractory Metal Powders.Current edition approved Oct.1,2011.Published November 2011.Originallyapproved in 1986.Last previous edition approved in 2006 as B761 06.DOI:10.1520/B0761-06R11.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 inversely proportional to the sample concentration 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 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