1、Designation: B 859 03Standard Practice forDe-Agglomeration of Refractory Metal Powders and TheirCompounds Prior to Particle Size Analysis1This standard is issued under the fixed designation B 859; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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 practice covers the de-agglomeration of refractorymetal powders and their compounds i
3、n preparation 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 pr
4、epared for particle size analysis usingthis practice with caution as to effectiveness until actualsatisfactory experience is developed.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 est
5、ablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecautionary statements, see Note 2.2. Referenced Documents2.1 ASTM Standards:B 243 Terminology of Powder Metallurgy2B 330 Test Method for Fisher Number of Metal Powd
6、ersand Related Compounds2B 430 Test Method for Particle Size Distribution of Refrac-tory Metal Powders and Related Compounds by Turbidim-etry2B 761 Test Method for Particle Size Distribution of MetalPowders and Related Compounds by X-Ray Monitoring ofGravity Sedimentation2B 821 Guide for Liquid Disp
7、ersion of Metal Powders andRelated Compounds for Particle Size Analysis2B 822 Test Method for Particle Size Distribution of MetalPowders and Related Compounds by Light Scattering22.2 ASTM Adjunct:ADJB0859 Detailed Drawings of Alternative Steel MillingBottles33. Terminology3.1 DefinitionsDefinitions
8、of powder metallurgy termscan be found in Terminology B 243.4. Significance and Use4.1 Refractory metal powders, such as tungsten and molyb-denum, are usually produced by hydrogen reduction at hightemperatures. Thus, they usually contain numerous large,strongly-sintered agglomerates. Many of the man
9、ufacturingprocesses 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 theindividual particulate size distribution, not the agglomeratesize distribution, is usually desired from a particle
10、 size analysisof these powders. This practice provides a procedure forbreaking down agglomerates into their constituent particles(de-agglomeration), without excessive fracture of the indi-vidual particles. The procedure is often referred to as labora-tory milling or rod milling.4.2 The laboratory mi
11、lling conditions specified in this guidehave been in use since 1965 as part of Test Method B 430. Thisguide was first published as a separate, stand-alone standard in1995 because of its applicability in preparing powder samplesfor analysis by other methods (for example, Test MethodsB 761 and B 822),
12、 in addition to Test Method B 430. Informa-tion on the development and establishment of the millingconditions 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 pa
13、rticles; some particle fracture may occur incertain powders. However, use of this practice does provide1This 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
14、 edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1995. Last previous edition approved in 2000 as B 859 95 (2000).2Annual Book of ASTM Standards, Vol 02.05.3Available from ASTM International Headquarters. Order Adjunct No.ADJB0859.4Michaels, A. I., “Turbidimetric Particle
15、 Size Distribution Theory: Applicationto Refractory Metal and Oxide Powders,” 1958 Symposium on Particle SizeMeasurement, ASTM STP 234, ASTM, 1959, pp. 207244.5Buerkel, W. A., “Turbidimetric Particle Size Analysis as Applied to TungstenPowder and the Carbide Industry,” Handbook of Metal Powders, A.
16、Poster, ed.,Reinhold Publishing Corp., New York, NY, 1966, pp. 2037.1*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.consistent particle size analysis results that have
17、 been found torelate well to powder behavior in numerous manufacturingprocesses.4.4 This practice shall be used for the de-agglomeration ofthe refractory metal powders and compounds listed in 1.1,when an evaluation of the individual particulate size distribu-tion is required from the subsequent part
18、icle size analysis. Itshall not be used when the agglomerate (as-is or as-supplied)size distribution is desired.4.5 This practice may be used in preparing samples for TestMethods B 330, B 430, B 761, B 822, and other particle sizeanalysis methods, prior to the dispersion procedure of GuideB 821, if
19、used.5. Apparatus5.1 Milling BottleThere are two alternative materials forthe milling container:5.1.1 Glass BottleRound laboratory solution bottle,250-mL capacity6, or a 250-mL, 140-mm high, 60-mm diam-eter, wide-mouth, flat-bottom centrifuge bottle, with cap orstopper, or5.1.2 Stainless Steel Bottl
20、eFabricated according to thedetailed drawings in Adjunct No. ADJB0859.5.2 Tungsten RodsFifty rods 75 6 3 mm long by 4.0 60.3 mm in diameter (approximately 3 in. by 0.15 in.), groundsurface.5.3 Laboratory Jar Roll Mill,7capable of rotating themilling bottle at 145 rpm.NOTE 1If a jar roll mill is not
21、available to give a bottle rpm of 145,the bottle can be either (1) set up on a lathe, or (2) built up in diameter andused on a faster rpm mill.5.4 Screen, No. 20 (850-m), and Bottom Pan.6. Procedure6.1 Place 30 6 0.1 g of tungsten, molybdenum, rhenium, ortantalum metal, or 50 6 0.1 g of tungsten car
22、bide powder in themilling bottle containing the 50 tungsten milling rods.6.2 Seal the milling bottle and rotate on the jar roll mill for60 min6 15 s at a bottle speed of 145 6 5 rpm. After the first5 min, check to be sure the rods are cascading inside the bottleby listening for the fast-paced, repea
23、ted “clinking” sound thatthe cascading rods make. If the rods are not cascading, stop themill, set the bottle upright momentarily, then replace the bottleon the mill and continue milling for the remaining 55 min (ifthe rods are now cascading; if not, repeat setting the bottleupright and restarting u
24、ntil they are).6.3 After milling, immediately screen the powder through aNo. 20 (850-m) screen to remove the milling rods. Dislodgeany milled powder that might remain in the bottle by placing acouple of screened rods in the bottle and “whipping” for a fewturns.NOTE 2Warning: The fresh metal surfaces
25、 produced during millingmay have a tendency to rapidly oxidize when the milling bottle is opened.Use caution when opening the bottle to avoid fire or explosion.6.4 Remove all the milled powder from the bottom pan andplace in a sample container.7. Particle Size Analysis7.1 If necessary, disperse the
26、milled powder according toGuide B 821.7.2 Immediately perform the desired particle size analysis.NOTE 3Since milled powder has a greater tendency than as-suppliedpowder to pick up moisture and oxidize, the analysis procedure should beinitiated immediately after milling is completed. For all practica
27、l pur-poses, however, two runs can be made in succession on each milledpowder. If more than two runs on the same milled powder are desired,provisions may be taken to lessen (elimination is not possible) the effectof humidity on the milled powder, such as immediate splitting of thesample and storage
28、under dry nitrogen or in a desiccator.8. Keywords8.1 de-agglomeration; laboratory-milled; laboratory mill-ing; molybdenum; particle size analysis; powders; refractorymetals; rhenium; rod-milled; rod milling; tantalum; tungsten;tungsten carbideSUMMARY OF CHANGESCommittee B09 has identified the locati
29、on of selected changes made to this standard since the last issue,B 85995 (2000), that may impact the use of this standard. (Approved Oct. 1, 2003.)(1) Stainless steel milling bottles were added as an alternativeto the glass bottles in Sections 5.1 and 5.1.2.(2) The adjunct number for the drawings o
30、f the stainless steelmilling bottles was added in Section 2.2.6The solution bottle No. 16158-128 furnished by VWR Scientific Co., P.O. Box7900, San Francisco, CA 94120, or bottle No. 05-587A furnished by FisherScientific, 711 Forbes Avenue, Pittsburgh, PA 15219, or their equivalent, have beenfound s
31、atisfactory.7The 0-300 rpm rollspeed, Model 755 Roll Mill, made by U.S. Stoneware, 40Whitney Rd., Mahwah, NJ 07430, or its equivalent, has been found satisfactory.B859032ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin
32、 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 mus
33、t be reviewed every five years andif 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 the
34、responsible technical committee, which 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).B859033
