1、Designation: E1251 11E1251 17Standard Test Method forAnalysis of Aluminum and Aluminum Alloys by SparkAtomic Emission Spectrometry1This standard is issued under the fixed designation E1251; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test met
3、hod describes the analysis of aluminum and its alloys by atomic emission spectrometry. The aluminumspecimen to be analyzed may be in the form of a chill cast disk, casting, foil, sheet, plate, extrusion, or some other wrought formor shape. The elements covered in the scope of this method are listed
4、in the table below.Element Tested Concentration Range(Wt %)Antimony 0.001 to 0.003Arsenic 0.001 to 0.006Beryllium 0.0004 to 0.24Bismuth 0.03 to 0.6Boron 0.0006 to 0.009Calcium 0.0002 to Chromium 0.001 to 0.23Cobalt 0.4 to Copper 0.001 to 5.5Gallium 0.02 to Iron 0.2 to 0.5Lead 0.04 to 0.6Lithium 0.00
5、03 to 2.1Magnesium 0.03 to 5.4Manganese 0.001 to 1.2Nickel 0.005 to 2.6Phosphorus 0.003 to Silicon 0.07 to 16Sodium 0.003 to 0.02Strontium 0.03 to Tin 0.03 to Titanium 0.001 to 0.12Vanadium 0.002 to 0.022Zinc 0.002 to 5.7Zirconium 0.001 to 0.12NOTE 1The concentration ranges given in the above scope
6、were established through cooperative testing (ILS) of selected reference materials. Therange shown for each element does not demonstrate the actual usable analytical range for that element. The usable analytical range may be extendedhigher or lower based on individual instrument capability, spectral
7、 characteristics of the specific element wavelength being used, and the availability ofappropriate reference materials.NOTE 2Mercury (Hg) is intentionally not included in the scope. Analysis of Hg in aluminum by spark atomic emission spectrometry (Spark-AES)is not recommended. Accurate analysis of H
8、g using this technique is compromised by the presence of an intense iron interference. Inaccurate reportingof Hg due to these interference effects can jeopardize the current designation of aluminum production as a mercury free mercury-free process. Todemonstrate compliance with legislated Hg content
9、 limits, use of an alternate method capable of analysis with a minimum reporting limit of 0.0001%or lower is recommended. Suitable techniques include but are not limited to glow discharge mass spectrometry, XRF, and cold vapor AA.1.2 This test method is suitable primarily for the analysis of chill c
10、ast disks as defined in Practices E716. Other forms may beanalyzed, provided that: (1) they are sufficiently massive to prevent undue heating, (2) they allow machining to provide a clean,flat surface, which creates a seal between the specimen and the spark stand, and (3) reference materials of a sim
11、ilar metallurgicalcondition and chemical composition are available.1 This test method is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommittee E01.04 on Aluminum and Magnesium.Current edition appro
12、ved March 15, 2011Sept. 15, 2017. Published June 2011October 2017. Originally approved in 1988. Last previous edition approved in 20072011as E1251 07.E1251 11. DOI: 10.1520/E1251-11.10.1520/E1251-17.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an
13、 indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to
14、 be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of thi
15、s standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. Specific safety and health statements are given in Section 10.1.4 This international standard was developed in accordance with internati
16、onally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E135 Termin
17、ology Relating to Analytical Chemistry for Metals, Ores, and Related MaterialsE158 Practice for Fundamental Calculations to Convert Intensities into Concentrations in Optical Emission SpectrochemicalAnalysis (Withdrawn 2004)3E172 Practice for Describing and Specifying the Excitation Source in Emissi
18、on Spectrochemical Analysis (Withdrawn 2001)3E305 Practice for Establishing and Controlling Atomic Emission Spectrochemical Analytical CurvesE406 Practice for Using Controlled Atmospheres in Spectrochemical AnalysisE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a
19、 Test MethodE716 Practices for Sampling and Sample Preparation of Aluminum and Aluminum Alloys for Determination of ChemicalComposition by Spark Atomic Emission SpectrometryE826 Practice for Testing Homogeneity of a Metal Lot or Batch in Solid Form by Spark Atomic Emission SpectrometryE876 Practice
20、for Use of Statistics in the Evaluation of Spectrometric Data (Withdrawn 2003)3E1329 Practice for Verification and Use of Control Charts in Spectrochemical AnalysisE1507 Guide for Describing and Specifying the Spectrometer of an Optical Emission Direct-Reading Instrument3. Terminology3.1 Definitions
21、For definitions of terms used in this Standard, refer to Terminology E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 alloy-type calibrationcalibration curves determined using calibrants from alloys with similar compositions.3.2.2 binary type binary-type calibrationcalibration curves de
22、termined using binary calibrants (primary aluminum to whichhas been added one specific element).3.2.3 global type global-type calibrationcalibration curves determined using calibrants from many different alloys withconsiderable compositional differences.3.2.3 alloy type calibrationcalibration curves
23、 determined using calibrants from alloys with similar compositions.3.2.4 two point two-point drift correctionthe practice of analyzing a high and low standardant for each calibration curve andadjusting the counts or voltage values obtained back to the values obtained on those particular standardants
24、 during the collectionof the calibration data. The corrections are accomplished mathematically and are applied to both the slope and intercept. Improvedprecision may be obtained by using a multi-point drift correction as described in Practice E1329.3.2.5 type standardizationmathematical adjustment o
25、f the calibration curves slope or intercept using a single standardant(reference material) at or close to the nominal composition for the particular alloy being analyzed. For best results, the standardantbeing used should be within 610 % of the composition (for each respective element) of the materi
26、al being analyzed.4. Summary of Test Method4.1 Aunipolar triggered capacitor discharge is produced in an argon atmosphere between the prepared flat surface of a specimenand the tip of a semi-permanent counter electrode. The energy of the discharge is sufficient to ablate material from the surface of
27、the sample, break the chemical or physical bonds, and cause the resulting atoms or ions to emit radiant energy. The radiant energiesof the selected analytical lines and the internal standard line(s) are converted into electrical signals by either photomultiplier tubes(PMTs) or a suitable solid state
28、 detector. The detector signals are electrically integrated and converted to a digitized value. Thesignals are ratioed to the proper internal standard signal and converted into concentrations by a computer in accordance withPractice E158.4.2 Three different methods of calibration defined in 3.2.13.2
29、.2, 3.2.23.2.3, and 3.2.33.2.1, are capable of giving the sameprecision, accuracy, and detection limit.4.2.1 The first method, binary calibration, employs calibration curves that are determined using a large number of high-puritybinary calibrants.This approach is used when there is a need to analyze
30、 almost the entire range of aluminum alloys. Because binary2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3
31、The last approved version of this historical standard is referenced on www.astm.org.E1251 172calibrants may respond differently from alloy calibrants, the latter are used to improve accuracy by applying a slope and/orintercept correction to the observed readings.4.2.2 The second method, global calib
32、ration, employs calibration curves that are determined using many different alloycalibrants with a wide variety of compositions. Mathematical calculations are used to correct for both alloy difference andinter-element effects. Like the method above, specific alloy calibrants may be used to apply a s
33、lope and/or intercept correction tothe observed readings.4.2.3 The third method, alloy calibration, employs calibration curves that are determined using different alloy calibrants thathave similar compositions.Again, specific alloy calibrants may be used to apply a slope and/or intercept correction
34、to the observedreadings.5. Significance and Use5.1 The metallurgical properties of aluminum and its alloys are highly dependent on chemical composition. Precise and accurateanalyses are essential to obtaining desired properties, meeting customer specifications, and helping to reduce scrap due to off
35、-gradematerial.5.2 This test method is applicable to chill cast specimens as defined in PracticePractices E716 and can also be applied to othertypes of samples provided that suitable reference materials are available. Also, other sample forms can be melted-down melteddown and cast into a disk, using
36、 an appropriate mold, as described in PracticePractices E716. However, it should be noted thatsome elements (for example, magnesium) readily form oxides, while some others (for example, sodium, lithium, calcium, andstrontium) are volatile, and may be lost to varying degrees during the melting proces
37、s.6. Recommended Analytical Lines and Potential Interferences6.1 Table 1 lists the analytical lines commonly used for aluminum analysis. Other lines may be used if they give comparableresults. Also listed are recommended concentration ranges, background equivalent concentrations (BEC), detection lim
38、its, usefullinear ranges, and potential interferences. The values given in this table are typical; actual values obtained are dependent oninstrument design.NOTE 3The BEC and detection limits listed in Table 1 have been attained with a spectrometer that has a reciprocal dispersion of 54 nm/mm and awo
39、rking resolution of 3.5 nm, using an entrance slit width of 25 m and exit slit widths of 50 m.7. Apparatus7.1 Specimen Preparation Equipment:7.1.1 Sampling Molds, for aluminum and the techniques of pouring a sample disk are described in PracticePractices E716. Chillcast samples, poured and cast as d
40、escribed within PracticePractices E716, shall be the recommended form in this test method.7.1.2 Lathe, capable of machining a smooth, flat surface on the reference materials and samples. A variable speed cutter, acemented carbide or polycrystalline diamond tool bit, and an automatic cross-feed cross
41、 feed are highly recommended. Properdepth of cut and desired surface finish are described in PracticePractices E716.7.1.3 Milling Machine, a milling machine can be used as an alternative to a lathe.NOTE 4It is strongly recommended that the same preparation machinery used to prepare the standards is
42、also used to prepare the samples. Differencesin surface characteristics may influence the analysis.7.2 Excitation Source, capable of producing a unipolar, triggered capacitor discharge. In todays instrumentation, the excitationsource is computer controlled and is normally programmed to produce: (1)
43、a high-energy pre-spark (of some preset duration), (2)a spark-type discharge (of some preset duration), (3) an arc type arc-type discharge (of some preset duration), and (4) a spark-typedischarge, during which, time resolved time-resolved measurements are made for improved detection limits (this may
44、 be optionalon some instruments).7.2.1 Typical parameters and exposure times are given in Table 2. It should be emphasized that the information presented isgiven as an example only and parameters may vary with respect to instrument model and manufacturer. For details on describingand specifying an e
45、xcitation source, please refer to Practice E172.7.3 Excitation Chamber, shall be designed with an upper plate that is smooth and flat so that it will mate (seal) perfectly withthe prepared surface of the sample specimen. The seal that is formed between the two will exclude atmospheric oxygen froment
46、ering the discharge chamber. The excitation chamber will contain a mounting clamp to hold the counter electrode. Theexcitation stand assembly will also have some type of clamp or device designed to hold the sample firmly against the top plate.Some manufacturers may provide for the top plate to be li
47、quid cooled to minimize sample heat-up during the excitation cycle. Theexcitation chamber will also be constructed so that it is flushed automatically with argon gas during the analytical burn cycle. Theexcitation chambers design should allow for a flow of argon gas to prevent the deposition of abla
48、ted metal dust on theinner-chamber quartz window(s). The excitation chamber will be equipped with an exhaust system that will safely dispose of theargon gas and the metal dust created during the excitation cycle. For reasons of health and cleanliness, the exhausted gas and dustshould not be vented d
49、irectly into the laboratory. To help with this situation, manufacturers have designed their instruments withsome type of exhaust/filter system to deal with this problem. The exhaust can then be vented into an efficient hood system.E1251 173TABLE 1 Recommended Analytical LinesElementWavelengthin Air(nm)ARecommendedConcentrationRange, %BackgroundEquivalent,%BCalculatedDetectionLimit, %C,DHighConcentrationIndex, %EInterferencesElement, (nm) and k, %FAluminum I 256.799 70-100I 266.039 70-100I 237.208 70-100Antimony I 231.147 0.001-0.5 0.17 0.0002 Co 231.166
