1、Designation: B890 07 (Reapproved 2012)Standard Test Method forDetermination of Metallic Constituents of Tungsten Alloysand Tungsten Hardmetals by X-Ray FluorescenceSpectrometry1This standard is issued under the fixed designation B890; the number immediately following the designation indicates the ye
2、ar 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. Scope1.1 This test method describes a procedure for the determi
3、-nation of the concentration, generally reported as mass percent,of the metallic constituents of tungsten-based alloys andhardmetals utilizing wavelength dispersive X-ray fluorescencespectrometry (XRF). This test method incorporates the prepa-ration of standards using reagent grade metallic oxides,l
4、ithium-borate compounds, and fusion techniques. This testmethod details techniques for preparing representative speci-mens of both powder and sintered tungsten-based material.This test method is accurate for a wide range of compositions,and can be used for acceptance of material to grade specifica-t
5、ions.1.2 This test method is applicable to mixtures of tungsten ortungsten carbide with additions of refractory metal carbidesand binder metals. Table 1 lists the most common elementalconstituents and their concentration range. Note that many ofthese occur as metallic carbides.1.3 This standard does
6、 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.2. Referenced Documents2.1 ASTM Stand
7、ards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE1361 Guide for Correction of Interelement Effects inX-Ray Spectrometric Analysis2.2 Handbook of Chemistry and Physics,367th ed3. Terminology3.1 For definitions of terms used in this test method, refer toTe
8、rminology E135.4. Summary of Test Method4.1 A suite of standards which closely match the chemicalcontent of the material to be analyzed are prepared usingreagent grade metallic oxides. Test samples are oxidized in ahigh-temperature furnace open to air. Fused glass specimensare prepared for these sta
9、ndards and for the test samples to beanalyzed. These specimens of oxidized tungsten or tungstencarbide alloys are irradiated with an energetic primary X-raybeam. The intensity of the resultant secondary X-rays, charac-teristic in energy, for each elemental constituent is measured bymeans of a suitab
10、le detector or combination of detectors afterdiffraction by a Bragg spectrometer. The concentration of eachconstituent element is calculated by comparison with standardsamples which closely match the chemical content of theanalyzed material. The calculation may be manual, incorporatea calibration cu
11、rve, or be performed by a computer programwhich incorporates correction routines for X-ray absorptionand enhancement effects (see Guide E1361).5. Significance and Use5.1 This test method allows the determination of the chemi-cal composition of powdered and sintered tungsten-basedhardmetals. This tes
12、t method is not applicable to materialwhich will not oxidize readily at high temperatures in air, suchas tungsten/copper or tungsten/silver alloys.5.2 This test method specified lithium-borate compoundsfor the glass fusion material. However, numerous other choicesare available. These include other l
13、ithium-borate compounds,sodium carbonate and borate mixtures, and others. The meth-odology specified here is still applicable as long as the samefusion mixture is used for both standards and specimens.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder
14、Productsand is the direct responsibility of Subcommit-tee B09.06 on Cemented Carbides.Current edition approved October 1, 2012. Published October 2012. Originallyapproved in 1998. Last previous edition approved in 2007 as B890 07. DOI:10.1520/B0890-07R12.2For referenced ASTM standards, visit the AST
15、M 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.3CRC Press, Boca Raton, FL, 1987.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
16、nshohocken, PA 19428-2959. United States16. Interferences6.1 Errors in XRF-determined compositional values may beencountered due to X-ray enhancement and absorption effectsdependent on the elements present and the X-ray line beingmeasured for a specific element. This effect can be reduced bydetermin
17、ation of correction factors using appropriate standardsand interelement correction routines, manual or computerized.6.2 Accuracy and precision of the analytical results obtainedfrom molybdenum-containing samples may be rendered unre-liable due to the sublimation and evaporation of molybdenumfrom the
18、 material during the oxidation step in specimenpreparation.6.3 Incorporation of the fusion method of specimen prepa-ration will:6.3.1 Reduce the deleterious influence of particle size ef-fects experienced when analyzing powder materials by varyingparticle size.6.3.2 Reduce inhomogenieties within a s
19、ample.6.3.3 Improve penetration of X rays.6.3.4 Reduce interelement interferences by tungsten on allother elements.7. Apparatus7.1 X-Ray Fluorescence Wavelength Dispersive Spectrom-eter7.2 FluxerAn automated high-temperature mixing devicecapable of melting, mixing, and pouring a molten liquidspecime
20、n into a proper casting dish, is highly preferred7.3 Analytical Balance, readability of 0.00001 g7.4 Toploading Balance, readability of 0.001 g7.5 Ordinary Laboratory Apparatus .7.6 One Pt - 5 % Au Casting Dish (minimum)7.7 One Pt - 5 % Au Crucible (minimum)7.8 Platinum Tipped Tongs7.9 Weighing Pape
21、r7.10 Chemical Spoon and Scoopula7.11 Ceramic Combustion Boat7.12 High Temperature Tube or Muffle Furnace, open to theatmosphere7.13 Self-adhering Stickers,34 by 1 in.7.14 High-Temperature marking pen7.15 Ceramic Mortar and Pestle7.16 Tungsten Carbide Mortar and Pestle7.17 Miniature Mixer, optional8
22、. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specification of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Ot
23、her grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Di-lithiumtetraborate (Li2B4O7):Lithiummetaborate(LiBO2), 66 + 34.8.3 Lithium Bromide (LiBr).8.4 Metallic Oxide Powder, high
24、est oxidation state forelements of interest; that is Co3O4,Cr2O3,Fe3O4, HfO2,MoO3,Nb2O5, NiO, Ta2O5,TiO2,V2O5, and WO3WarningSeveral of the metallic oxides used in this testmethod are highly toxic and possibly carcinogenic, such asCr2O3, NiO, or V2O5. Extreme care should be used at all timeswhen han
25、dling this material (especially V2O5). All mixing ofstandards should be performed in a fume hood. All of thelithium compounds are water-soluble and therefore able to beabsorbed into the body by inhalation and possibly by absorp-tion through the skin. This material should be weighed in afume hood.8.5
26、 Citric Acid (HOC(COOH)(CH2COOH)2.8.6 Silicic Acid (SiO2xH20).9. Specimen Preparation9.1 Prepare specimens of the material to be analyzed byoxidizing, weighing, and fusing starting powders, chips, orcrushed sintered hard metal samples.9.2 Place 3 to5gofpowdered specimen in a labeledceramic combustio
27、n boat. If a sintered sample is to beanalyzed, then the sample must be crushed or pulverized intosmall pieces or chips must be produced by machining prior toplacement in the combustion boat. To crush or pulverize asample, a tungsten carbide mortar and pestle should be used toreduce the incidence of
28、contamination.9.3 Oxidize the specimen in the heat zone of a high-temperature tube or muffle furnace open to the atmosphere at825 6 25C. All specimens must be oxidized.9.4 When the specimen has been completely oxidized (4 to6 h), remove from the furnace and allow to cool.4Reagent Chemicals, American
29、 Chemical Society Specification, AmericanChemical 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 Formulatory, U
30、.S. Pharmaceutical Convention, Inc. (USPC),Rockvale, MD.TABLE 1 Elemental Constituents and Concentration RangeElement Concentration, Mass %(minimum - maximum)Chromium (Cr) 0.05 - 5.0Cobalt (Co) 0.05 - 40Hafnium (Hf) 0.05 - 2.0Iron (Fe) 0.05 - 2.0Molybdenum (Mo) 0.05 - 5.0Nickel (Ni) 0.05 - 30Niobium
31、 (Nb) 0.05 - 15Tantalum (Ta) 0.05 - 30Titanium (Ti) 0.05 - 30Vanadium (V) 0.05 - 2.0B890 07 (2012)2NOTE 1Complete oxidation of a sintered magnetic tungsten hardmetal sample can be checked by testing the cool oxidized chips with amagnet. If any of the chips are still magnetic, recrush the sample and
32、placeback in the furnace for further oxidation.9.5 Pour the specimen onto a clean sheet of paper or into aclean mortar and gently crush with a pestle.9.6 Transfer the specimen to a labeled specimen vial.9.7 In a fume hood, weigh out 15.000 6 0.001 g of thedilithium tetraborate: lithiummetaborate mix
33、ture, 1.5 6 0.001g of the silicic acid, and 0.200 6 0.001 g of LiBr and transferto a clean sample vial. This mixture will be referred to as the“fusion mixture.” Seal and store until needed.NOTE 2Other fusion materials can be used. See 5.2.9.8 In a fume hood, transfer the fusion mixture to a platinum
34、crucible immediately prior to weighing of the oxidized samplematerial.9.9 Weigh out 1.0000 6 0.00005 g of oxidized specimenand transfer to the platinum crucible. Mix gently with thefusion mixture.NOTE 3If there is not enough sample to make a standard fusion, or theamount of the total mixture is too
35、large for the casting dish, proportionateamounts of oxidized test sample and fusion mixture can be utilized toprepare a specimen recognizing that larger fractional errors may beincurred in the analysis. This should only be used when absolutelynecessary.9.10 Using the fluxer, melt the specimen at 130
36、0 6 100Cand cast into a heated platinum casting dish.9.10.1 WarningThe process of making glass fusionsexposes personnel to high-temperature liquids. Extreme careshould be exercised while preparing these samples. These hightemperatures also cause some volatilization of the lithiumcompounds. The fluxe
37、r should have an exhaust hood to removethese gases from the facility. The lithium compounds used inthis procedure are hygroscopic. Material open to the atmo-sphere for an extended period of time will absorb moisture.Exposure of this material to subsequent high heat will causerapid formation of steam
38、 and may cause spattering of themolten glass onto the instrument and possibly the operator.9.11 While the fused specimen is cooling, remove thecrucible from the instrument with the platinum-tipped tongsand cool under a stream of water.9.12 Place the crucible in a 1000-mL beaker which has a2-volume p
39、ercent solution of citric acid. Put the beaker on a hotplate and warm the solution. The crucible should be clean inapproximately 30 min. Remove the crucible from the acid bathwith tongs and rinse with water. Dry the crucible and store.9.13 When the fused specimen is cool, remove from thecasting dish
40、 by gripping the dish firmly with tongs, turning thedish over, and gently tapping against a clean paper. The dishand fused specimen should cleanly separate. Label the fusedspecimen with a self-adhering tag.NOTE 4Any evidence of wetting between the specimen and theplatinum crucible or casting dish is
41、 an indication that the specimen hasreacted with these vessels and is not a valid representative sample.9.14 If the fusion crystallizes or fractures on cooling, crushthe fusion and recast. If the fused specimen cannot be removedfrom the platinum casting dish with very light tapping, dissolvethe spec
42、imen from the dish using a warm 2-volume percentcitric acid solution. Prepare a new specimen in accordance with9.7-9.10.CautionExcessive prying or tapping of the crystallizedspecimen while it is in the dish will damage the platinum ware.10. Standardization of Spectrometer and Analysis10.1 Based on t
43、he X-ray spectrometer configuration andinstrument manufacturers operating instructions, determinethe instrument operating parameters to provide optimum spec-tral analysis for each element being analyzed in a given matrix.Table 2 provides the approximate X-ray peak positions (Braggangle - 2) and crys
44、tals recommended for each of the elementsof interest.10.2 If required, normalize the X-ray spectrometer operat-ing parameters to obtain the appropriate secondary x-rayintensities from the reference standards utilized.10.3 Measure X-ray intensities on a sufficient number offused standards to establis
45、h a calibration curve (intensityversus concentration of analyte) for each element of interest.NOTE 5The number of standards sufficient to establish a calibrationcurve is dependent on the range of concentrations to be analyzed for eachelement. In all cases, a minimum of six standards is required.10.4
46、 Calibration curves may be established manually, orcorrections for interelement effects may be calculated usingXRF vendor-supplied computer software.NOTE 6Accuracy of a given interelement correction routine can beverified by including one or more reference standards as “blind” un-knowns as part of a
47、n analysis.11. Procedure11.1 Obtain X-ray intensity data from the fused test speci-mens.11.2 Calculate relative concentrations utilizing appropriatecalibration curves and absorption and enhancement correctionroutines, if available.12. Report12.1 Report the results of the analysis as mass percent of
48、themetallic or carbide constituent. Report average values ofreplicate determinations, either measurements or samples, ifperformed, along with the concentration range. The correctionTABLE 2 Analytical X-ray LinesElementSymbolShellSeriesReflectionOrderBraggAngle 2QWavelength,ACrystalCo Ka 1 52.788 1.7
49、906 LiF100Cr Ka 1 69.368 2.2913 LiF100Fe Ka 1 57.526 1.9376 LiF100Hf La 1 45.880 1.5690 LiF100Mo Ka 1 20.276 0.7092 LiF100Nb Ka 1 21.340 0.7461 LiF100Ni Ka 1 48.632 1.6594 LiF100Ta La 1 64.640 1.5222 LiF110Ti Ka 1 86.186 2.7502 LiF100VKa 1 123.172 2.5054 LiF110B890 07 (2012)3routine employed to determine final concentration valuesshould also be specified by the party completing the analysis,if required.12.2 The parties involved may require reporting of theactual X-ray spectrometer operating parameters employed foreach element of interest. These typically include
