1、Designation:B85913Standard Practice forDe-Agglomeration of Refractory Metal Powders and TheirCompounds Prior to Particle Size Analysis1This standard is issued under the fixed designation B859;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,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 practice covers the de-agglomeration of refractorymetal powders and their compounds in preparation
3、 for particlesize analysis.1.2 Experience has shown that this practice is satisfactoryfor the de-agglomeration of elemental tungsten,molybdenum,rhenium,and tantalum metal powders,and tungsten carbide.Other metal powders(for example,elemental metals,carbides,and nitrides)may be prepared for particle
4、size analysis usingthis practice with caution as to effectiveness until actualsatisfactory experience is developed.1.3 With the exception of the values for mass,for which theuse of the gram(g)unit is the long-standing industry practice,the values stated in SI are to be regarded as standard.No otheru
5、nits of measure are included in this standard.1.4 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 regulato
6、ry limitations prior to use.For specificprecautionary statements,see Note 2.2.Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyB330 Test Methods for Estimating Average Particle Size ofMetal Powders and Related Compounds Using Air Per-meabilityB761 Test Method for Particle
7、 Size Distribution of MetalPowders and Related Compounds by X-Ray Monitoringof Gravity SedimentationB821 Guide for Liquid Dispersion of Metal Powders andRelated Compounds for Particle Size AnalysisB822 Test Method for Particle Size Distribution of MetalPowders and Related Compounds by Light Scatteri
8、ng2.2ASTM Adjunct:ADJB0859 Detailed Drawings of Alternative Steel MillingBottles33.Terminology3.1 DefinitionsDefinitions of powder metallurgy termscan be found in Terminology B243.4.Significance and Use4.1 Refractory metal powders,such as tungsten andmolybdenum,are usually produced by hydrogen reduc
9、tion athigh temperatures.Thus,they usually contain numerous large,strongly-sintered agglomerates.Many of the manufacturingprocesses using these powders involve a milling step or somesimilar treatment or depend on the individual particulate size,not on the agglomerate size.4Thus,a knowledge of theind
10、ividual particulate size distribution,not the agglomeratesize distribution,is usually desired from a particle size analysisof these powders.This practice provides a procedure forbreaking down agglomerates into their constituent particles(de-agglomeration),without excessive fracture of the indi-vidua
11、l particles.The procedure is often referred to as labora-tory milling or rod milling.4.2 The laboratory milling conditions specified in this guidehave been in use since 1965,initially as part of a particle sizeanalysis test method.This guide was first published as aseparate,stand-alone standard in 1
12、995 because of its applica-bility in preparing powder samples for analysis by other1This practice 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 edition approved Oc
13、t.1,2013.Published October 2013.Originallyapproved in 1995.Last previous edition approved in 2003 as B859 03(2008)1.DOI:10.1520/B0859-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume infor
14、mation,refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International Headquarters.Order Adjunct No.ADJB0859.4Michaels,A.I.,“Turbidimetric Particle Size Distribution Theory:Applicationto Refractory Metal and Oxide Powders,”1958 Symposium on Particle SizeMeasuremen
15、t,ASTM STP 234,ASTM,1959,pp.207244.*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 methods as well(for example,Test Methods B761 and B822).Information on the development and
16、 establishment of themilling conditions here specified can be found in the footnotedreference.54.3 The milling procedure described in this practice doesnot necessarily break down only agglomerates without fractur-ing individual particles;some particle fracture may occur incertain powders.However,use of this practice does provideconsistent particle size analysis results that have been found torelate well to powder behavior in numerous manufacturingprocesses.4.4 This practice shall be used for the