1、Designation: E1251 11Standard 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 revision, t
2、he 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 Department of Defense.1. Scope1.1 This test method describes
3、 the analysis of aluminum andits 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 arelisted in the table belo
4、w.ElementTested 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 0.0003 to 2.1Magnesium
5、 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 0.03toTitanium 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 wereestablished thro
6、ugh cooperative testing (ILS) of selected reference mate-rials. The range shown for each element does not demonstrate the actualusable analytical range for that element. The usable analytical range maybe extended higher or lower based on individual instrument capability,spectral characteristics of t
7、he specific element wavelength being used andthe availability of appropriate reference materials.NOTE 2 Mercury (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 Hg using thistechnique
8、is compromised by the presence of an intense iron interference.Inaccurate reporting of Hg due to these interference effects can jeopardizethe current designation of aluminum production as a mercury free process.To demonstrate compliance with legislated Hg content limits, use of analternate method ca
9、pable of analysis with a minimum reporting limit of0.0001% or lower is recommended. Suitable techniques include but arenot limited to glow discharge mass spectrometry, XRF, and cold vaporAA.1.2 This test method is suitable primarily for the analysis ofchill cast disks as defined in Practices E716. O
10、ther forms maybe analyzed, provided that: (1) they are sufficiently massive toprevent undue heating, (2) they allow machining to provide aclean, flat surface, which creates a seal between the specimenand the spark stand, and (3) reference materials of a similarmetallurgical condition and chemical co
11、mposition are avail-able.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 pri
12、or to use. Specific safety andhealth statements are given in Section 10.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE158 Practice for Fundamental Calculations to ConvertIntensities into Concentrations in Optical E
13、mission Spec-trochemical Analysis3E172 Practice for Describing and Specifying the ExcitationSource in Emission Spectrochemical Analysis3E305 Practice for Establishing and Controlling AtomicEmission Spectrochemical Analytical Curves1This test method is under the jurisdiction of ASTM Committee E01 onA
14、nalytical Chemistry for Metals, Ores, and Related Materials and is the directresponsibility of Subcommittee E01.04 on Aluminum and Magnesium.Current edition approved March 15, 2011. Published June 2011. Originallyapproved in 1988. Last previous edition approved in 2007 as E1251 07. DOI:10.1520/E1251
15、-11.2For 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.3Withdrawn. The last approved version of this historical
16、standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E406 Practice for Using Controlled Atmospheres in Spec-trochemical AnalysisE691 Practice for Conducting an Interlaboratory Study toDetermine the Pr
17、ecision of a Test MethodE716 Practices for Sampling and Sample Preparation ofAluminum and Aluminum Alloys for Determination ofChemical Composition by Spectrochemical AnalysisE826 Practice for Testing Homogeneity of a Metal Lot orBatch in Solid Form by Spark Atomic Emission Spectrom-etryE876 Practice
18、 for Use of Statistics in the Evaluation ofSpectrometric Data3E1329 Practice for Verification and Use of Control Charts inSpectrochemical AnalysisE1507 Guide for Describing and Specifying the Spectrom-eter of an Optical Emission Direct-Reading Instrument3. Terminology3.1 DefinitionsFor definitions o
19、f terms used in this Stan-dard, refer to Terminology E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 binary type calibrationcalibration curves deter-mined using binary calibrants (primary aluminum to which hasbeen added one specific element).3.2.2 global type calibrationcalibration cur
20、ves deter-mined using calibrants from many different alloys with con-siderable compositional differences.3.2.3 alloy type calibrationcalibration curves determinedusing calibrants from alloys with similar compositions.3.2.4 two point drift correctionthe practice of analyzing ahigh and low standardant
21、 for each calibration curve andadjusting the counts or voltage values obtained back to thevalues obtained on those particular standardants during thecollection of the calibration data. The corrections are accom-plished mathematically and are applied to both the slope andintercept. Improved precision
22、 may be obtained by using amulti-point drift correction as described in Practice E1329.3.2.5 type standardizationmathematical adjustment of thecalibration curves slope or intercept using a single standardant(reference material) at or close to the nominal composition forthe particular alloy being ana
23、lyzed. For best results thestandardant being used should be within 610 % of the com-position (for each respective element) of the material beinganalyzed.4. Summary of Test Method4.1 A unipolar triggered capacitor discharge is produced inan argon atmosphere between the prepared flat surface of aspeci
24、men and the tip of a semi-permanent counter electrode.The energy of the discharge is sufficient to ablate material fromthe surface of the sample, break the chemical or physicalbonds, and cause the resulting atoms or ions to emit radiantenergy. The radiant energies of the selected analytical lines an
25、dthe internal standard line(s) are converted into electrical signalsby either photomultiplier tubes (PMTs) or a suitable solid statedetector. The detector signals are electrically integrated andconverted to a digitized value. The signals are ratioed to theproper internal standard signal and converte
26、d into concentra-tions by a computer in accordance with Practice E158.4.2 Three different methods of calibration defined in 3.2.1,3.2.2 and 3.2.3, are capable of giving the same precision,accuracy and detection limit.4.2.1 The first method, binary calibration, employs calibra-tion curves that are de
27、termined using a large number ofhigh-purity binary calibrants. This approach is used when thereis a need to analyze almost the entire range of aluminum alloys.Because binary calibrants may respond differently from alloycalibrants, the latter are used to improve accuracy by applyinga slope and/or int
28、ercept correction to the observed readings.4.2.2 The second method, global calibration, employs cali-bration curves that are determined using many different alloycalibrants with a wide variety of compositions. Mathematicalcalculations are used to correct for both alloy difference andinter-element ef
29、fects. Like the method above, specific alloycalibrants may be used to apply a slope and/or interceptcorrection to the observed readings.4.2.3 The third method, alloy calibration, employs calibra-tion curves that are determined using different alloy calibrantsthat have similar compositions. Again, sp
30、ecific alloy calibrantsmay be used to apply a slope and/or intercept correction to theobserved readings.5. Significance and Use5.1 The metallurgical properties of aluminum and its alloysare highly dependent on chemical composition. Precise andaccurate analyses are essential to obtaining desired prop
31、erties,meeting customer specifications and helping to reduce scrapdue to off-grade material.5.2 This test method is applicable to chill cast specimens asdefined in Practice E716 and can also be applied to other typesof samples provided that suitable reference materials areavailable. Also, other samp
32、le forms can be melted-down andcast into a disk, using an appropriate mold, as described inPractice E716. However, it should be noted that some elements(for example, magnesium) readily form oxides, while someothers (for example, sodium, lithium, calcium, and strontium)are volatile, and may be lost t
33、o varying degrees during themelting process.6. Recommended Analytical Lines and PotentialInterferences6.1 Table 1 lists the analytical lines commonly used foraluminum analysis. Other lines may be used if they givecomparable results.Also listed are recommended concentrationranges, background equivale
34、nt concentrations (BEC), detec-tion limits, useful linear ranges, and potential interferences.The values given in this table are typical; actual valuesobtained are dependent on instrument design.NOTE 3The BEC and detection limits listed in Table 1 have beenattained with a spectrometer that has a rec
35、iprocal dispersion of 54 nm/mmand a working resolution of 3.5 nm, using an entrance slit width of 25 mand exit slit widths of 50 m.7. Apparatus7.1 Specimen Preparation Equipment:7.1.1 Sampling Molds, for aluminum and the techniques ofpouring a sample disk are described in Practice E716. ChillE1251 1
36、12TABLE 1 Recommended Analytical LinesElementWavelengthin Air(nm)ARecommendedConcentrationRange, %BackgroundEquivalent,%BCalculatedDetectionLimit, %C,DHighConcentrationIndex, %EInterferencesElement, l(nm) and k, %FAluminum I 256.799 70-100I 266.039 70-100I 237.208 70-100Antimony I 231.147 0.001-0.5
37、0.17 0.0002 Co 231.166 0.6I 259.806 0.001-0.5 0.0002 Fe 259.837Mn 259.817 0.01Arsenic 234.984 0.005-0.1Beryllium I 234.861 0.0001-0.05 0.001 0.00003II 313.042 0.0001-0.05 0.0035 0.00001332.134 0.0001-0.05 0.00001Bismuth I 306.772 0.001-0.7 0.04 0.0002Boron I 249.773 0.0001-0.05 0.002 0.0001* Fe 249.
38、782 0.001Mn 249.778 0.007I 249.678 0.0001-0.05I 208.959 0.0001-0.05 Mo 208.952 0.13Cadmium I 228.802 0.001-1 0.05 20 Fe 296.128II 224.700 0.01-5 0.03 0.0005* 5I 510.554 0.05-20 0.32 0.01* 20Gallium I 294.364 0.001-0.05 0.015 11I 383.231G0.01-11 0.015 0.002* 11I 383.826 0.1-11I 518.362 0.01-11 0.02 0
39、.002* 11Manganese I 403.076G0.001-0.1 0.028 0.0001*II 259.373II 293.3060.0005-0.50.001-20.0040.0060.000050.0002*0.21.1II 346.033B 0.01-2Nickel I 341.476 0.001-2 0.02 2.5 Zr 341.466 0.01I 310.188 0.005-4 0.05 0.001* 5II 231.604 0.001-2 0.015 0.0005* 24 Cr 390.566 0.09I 212.415 0.05-24 0.5 0.05 24Silv
40、er I 328.068 0.0005-0.1I 338.289 0.0001-0.1 10I 466.848 0.05-1.5Sodium I 588.995 0.0001-0.05 0.0015 10Titanium II 334.904 0.0005-0.5 0.004 8I 481.053 0.01-10 0.07 0.001* 10I 472.216 0.01-10 0.26 0.0015 10Zirconium II 339.198 0.001-1 0.02 0.001*II 349.621G0.001-1 0.006 0.0001AI = atom line, II = ion
41、line. Second (2nd) indicates that the second order shall be used, where available.BBackground Equivalent Concentration (BEC)The concentration at which the signal due to the element is equal to the signal due to the background.CIn this test method, the calculated detection limit was measured by calcu
42、lating the standard deviation of ten consecutive burns on a specimen with elementconcentration(s) at levels below ten times the expected detection limit.DSee footnote C. For values marked with an asterisk (*) the available data were for a concentration greater than ten (10) times but less than a hun
43、dred (100) times theexpected detection limit.EHigh Concentration IndexThe concentration at which the slope of the calibration curve drops below 0.75.FInterference Factor, kThe apparent increase in the concentration of the element being determined, expressed in percent, due to the presence of 1.0 % o
44、f theinterfering element.GUseful analytical lines with improved signal to background ratios due to the complete removal of C-N background by the argon atmosphere.HIf phosphorus is to be determined, the most sensitive line appears to be the 178.231 nm in the second order which requires either a vacuu
45、m or a gas filled spectrometer.The vacuum spectrometer should be operated at a pressure of 25 microtorr or less. The gas filled spectrometer will be charged with nitrogen to a positive pressure of slightlyover one atmosphere (101 k pa). Optimum results are obtained by using a background channel that
46、 has been profiled “off peak” of the first order 178.231 nm phosphorusline as the internal standard. The ratio of P 178.231 nm (2nd) / background near the 178.231 nm (1st) is plotted against % phosphorus. Even with this compensation forvariability in background, alloys with highly different composit
47、ions of major alloying elements, particularly silicon, require separate reference materials and analytical curves.TABLE 2 Typical Excitation Source Electrical ParametersParameterHigh EnergyPre-sparkSpark ArcResistance, V 1115Inductance, H 30 130 30Volts, V 400 400 400Frequency, Hz 300 300 300Capacit
48、ance, F 12 3 5Time, s 10 5 5E1251 114cylinder that contains liquid argon or possibly from a centralsupply (liquid only). It is essential that only argon gas meetingthe minimum purity of 99.995 % be used. A lower purity gradeof argon, such as a “welding grade,” should not be used. Thedelivery system
49、shall be composed of a two-stage type (high/low pressure) regulator of all-metal construction with two-pressure gages. Delivery tubing must not produce any contami-nation of the argon stream. Refrigerator grade copper tubing isrecommended. The gages on the regulator will allow for theadjustment of the gas pressure to the instrument. Deliverypressure specifications will vary with instrument manufacturer.Please note that the delivery tube connections should be madewith all metal seals and the delivery tubing itself should be keptas short as possible (Note 5).
