1、Designation: E 2050 99 (Reapproved 2004)Standard Test Method forDetermination of Total Carbon in Mold Powders byCombustion-Infrared Absorption Method1This standard is issued under the fixed designation E 2050; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case 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. Scope1.1 This test method covers the determination of totalcarbon in mold powders in th
3、e concentration range from 1 to25 %.1.2 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 limi
4、tations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 50 Practices for Apparatus, Reagents, and Safety Precau-tions for Chemical Analysis of MetalsE 135 Terminology Relating to Analytical C
5、hemistry forMetals, Ores, and Related MaterialsE 882 Guide for Accountability and Quality Control in theChemical Analysis LaboratoryE 1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, and Oxygen in Steel and in Iron, Nickel, andCobalt AlloysE 1601 Practice for Conducting an Interlabora
6、tory Study toEvaluate the Performance of an Analytical MethodE 1763 Guide for Interpretation and Use of Results from theInterlaboratory Testing of Chemical Analysis Methods3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology E 135.3.2 Definitions:3.2.1 mold powder
7、, nin the continuous-casting of steel, ametallurgical flux used to provide lubrication of the mold,enhance heat transfer at the strand-mold interface, and providethermal insulation of the liquid metal surface to preventunwanted solidification.3.2.1.1 DiscussionKey chemical components of thesepowders
8、 are fluorides, the oxides of silicon and calcium, andcarbon.4. Summary of Test Method4.1 Carbon in the test sample is converted in a furnace to amixture of carbon dioxide and carbon monoxide by combus-tion in a stream of oxygen. Full conversion of carbon monox-ide to carbon dioxide occurs by the pa
9、ssage of sample gasesthrough a catalytic heater assembly. The amount of carbondioxide is measured by infrared absorption. Any interferencefrom halogens in the sample is eliminated by placement of ahalogen trap between the furnace and the analyzer.5. Significance and Use5.1 This test method for the d
10、etermination of total carbon inmold powders is primarily intended to test such materials forcompliance with compositional specifications. It is assumedthat all who use this test method will be trained analystscapable of performing common laboratory procedures skill-fully and safely. It is expected t
11、hat the work will be performedin a properly equipped laboratory and that proper wastedisposal procedures will be followed. Appropriate qualitycontrol practices must be followed such as those described inGuide E 882.6. Rounding Calculated Values6.1 Calculated values shall be rounded in accordance wit
12、h3.4 to 3.6 of Practice E 29.1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved Ma
13、y 1, 2004. Published July 2004. Originally approvedin 1999. Last previous edition approved in 1999 as E 205099.2For 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 s
14、tandards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Interlaboratory Studies7.1 This test method has been evaluated in accordance withPractice E 1601 and Guide E 1763. The lower limit i
15、n thescope of this test method specifies the lowest analyte contentthat may be analyzed with an acceptable error.8. Interferences8.1 Halogens, normally present in mold powders as fluoride,will interfere with this test method. A halogen trap, asdescribed in 9.4, must be installed in the measure line
16、betweenthe furnace and analyzer to prevent this interference.9. Apparatus9.1 Combustion-Infrared Absorption Carbon Analyzer,equipped with a combustion chamber, oxygen carrier stream,halogen trap, catalytic heater assembly, and infrared absorptiondetector, suitable for the analysis of carbon from 1 t
17、o 25 % inmold powders. Instruments, such as those in Test MethodsE 1019, which can be shown to give equivalent results mayalso be used for this test method.9.2 CruciblesUse ceramic crucibles that meet or exceedthe specifications of those recommended by the manufacturerof the instrument.9.3 Crucible
18、Tongs, capable of handling recommended cru-cibles.9.4 Halogen (Fluorine/Chlorine) Trap3, available from theinstrument manufacturer as a kit, consisting of the parts andnecessary reagents for assembly. Follow the manufacturersinstructions for the assembly, installation, use, and propermaintenance of
19、the trap.9.5 Metal Scoop, for dispensing metal chips.10. Reagents and Materials10.1 Iron Chip, high purity (6 to +20 mesh).10.2 Oxygen, 99.5 % purity recommended. Other grades ofoxygen may be used if low and consistent blank readings areobtained.10.3 Tungsten/Tin Accelerator, high purity.NOTE 1Coppe
20、r chip accelerator (20 to +30 mesh) may be used inplace of Tungsten/Tin.11. Hazards11.1 For precautions to be observed in the use of reagentsand apparatus in this method, refer to Practices E 50 and TestMethods E 1019.11.2 Use care when handling hot crucibles and whenoperating furnaces to avoid pers
21、onal injury by either burn orelectrical shock.12. Sampling and Sample Preparation12.1 Materials SafetySamples must be prepared, stored,and disposed of in accordance with the materials and safetyguidelines in Practices E 50.12.2 Prepared SamplePulverize or grind the laboratorysample until 100 % passe
22、s a No. 100 (150-mu) sieve. Store ina suitable glass or plastic container.13. Preparation of Apparatus13.1 Test the furnace and analyzer to ensure the absence ofleaks. Prepare the analyzer for operation in accordance with themanufacturers instructions.14. Calibration14.1 Calibration Reference Materi
23、alsTungsten carbide(6.10 % total carbon), NIST SRM 276b, or equivalent; siliconcarbide (29.43 % total carbon), NIST SRM 112b, or equiva-lent.14.2 Determination of Blank:14.2.1 Enter 1.000-g weight into the weight stack, followingthe instrument manufacturers recommended procedure.14.2.2 Add 1.000 6 0
24、.005 g of accelerator and 1.000 60.005 g of iron chip to the crucible.14.2.3 Place the crucible on the furnace pedestal and ana-lyze in accordance with the manufacturers instructions.14.2.4 Repeat 14.2.1-14.2.3 a minimum of three times.14.2.5 Enter the average blank following the routine out-lined i
25、n the manufacturers instruction manual.14.3 Calibration Procedure:14.3.1 Weigh ;0.25-g tungsten carbide calibration refer-ence material into a ceramic crucible and enter the weight intothe weight stack, following the instrument manufacturersrecommended procedure.14.3.2 Add 1.000 6 0.005 g of acceler
26、ator and 1.000 60.005 g of iron chip to the crucible.14.3.3 Place the crucible on the furnace pedestal and ana-lyze in accordance with the manufacturers instructions.14.3.4 Repeat 14.3.1-14.3.3 a minimum of three times andcalibrate the instrument following the calibration procedure inaccordance with
27、 the manufacturers instruction manual.14.3.5 Verify the calibration by analyzing the calibrationreference material again. It should fall within the uncertaintiesof the certified value. If not, determine and correct the cause,and repeat 14.3.1-14.3.4.3Fluorine/Chlorine Trap Kit, Part Number 769-641,
28、available from the LECOCorp., 820 Commonwealth Drive, Thornhill Industrial Part, Warrendale, PA 15086,has been found satisfactory for this purpose.TABLE 1 Statistical Information, Carbon Combustion/Infrared MethodTest Material Number ofLaboratoriesCarbon Found, % Minimum SD (SM,E 1601)Reproducibilit
29、y SD,(Sg, E 1601)Reproducibility Index(R, E 1601)Rrel%B 7 1.2046 0.00601 0.02960 0.08288 6.88A 7 3.1219 0.01269 0.04843 0.13559 4.34C 7 6.5514 0.04774 0.09215 0.25803 3.94D 7 10.5121 0.05788 0.10579 0.29620 2.82E 7 15.1121 0.04964 0.14730 0.41244 2.73F 7 19.7121 0.11949 0.25294 0.70824 3.59G 7 29.42
30、50 0.38830 0.60179 1.6850 5.73E 2050 99 (2004)214.3.6 Verify linearity of the instrument response by ana-lyzing a silicon carbide (29.43 % total carbon) standard refer-ence material. Results should fall within the uncertainties ofthe certificate value expected tolerance. If not, identify andcorrect
31、the problem before proceeding with the analysis ofsamples.15. Procedure15.1 Assemble the apparatus and condition it in accordancewith Section 13.15.2 Sample Analysis:15.2.1 Weigh, to the nearest 0.1 mg, an appropriately sizedsample into a ceramic crucible, in accordance with the follow-ing:Carbon, %
32、 Sample Weight, g1-6 ;0.256-10 ;0.2010 - 20 ;0.1520 - 25 ;0.075Enter the weight into the weight stack, following theinstrument manufacturers recommended procedure.15.2.2 Add 1.000 6 0.005 g of accelerator and 1.000 60.005 g of iron chip to the crucible.15.2.3 Place the crucible on the furnace pedest
33、al and ana-lyze.15.2.4 Analyze each sample in duplicate, recording eachvalue.15.2.5 Check instrument calibration (see 14.3.5) after every2 sets of duplicate sample runs.16. Calculation16.1 Most commercially available instruments calculatepercent concentrations directly, including corrections for bla
34、nkand sample weight, so calculations by the analyst are notrequired. If, however, the analyzer does not compensate forblank and sample values, then use the following formula:Carbon, % 5 A2B! 3 C/D (1)where:A = DVM reading for sample,B = DVM reading for blank,C = weight compensator setting, andD = sa
35、mple weight, g.16.2 Round the results and report to 2 decimal places forvalues less than 10 % carbon, and to 1 decimal place for valuesequal to or greater than 10 % carbon. Examples: 4.15 %,15.6 %.17. Precision and Bias417.1 PrecisionSeven laboratories cooperated in testingthis test method. Table 1s
36、ummarizes the precision information.Table 2 displays the reproducibility expected for results at anumber of carbon values.17.2 BiasThe accuracy of this test method could not beevaluated because certified reference materials of mold pow-ders were unavailable. Table 3 compares the means from thistest
37、method with results on the same materials by thecombustion/gravimetric carbon test method. The differencesshow that the combined bias of both test methods does notexceed 60.1 % carbon.18. Keywords18.1 carbon; combustion; infrared absorption; moldpowders4A research report is available from ASTM Inter
38、national headquarters. RequestRR:E011029.TABLE 2 Predicted Reproducibility at Various Carbon ContentsCarbon, % RRref%0.5 0.079 15.71.0 0.083 8.32.0 0.109 5.45.0 0.178 3.610 0.329 3.320 0.645 3.2E 2050 99 (2004)3ASTM International takes no position respecting the validity of any patent rights asserte
39、d in connection with any item mentionedin 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 th
40、e responsible technical committee and must 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
41、careful consideration at a meeting of theresponsible 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 Internat
42、ional, 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).TABLE 3 Comparison Between IR and Gravimetric CarbonTest Material IR Carbon, % GravimetricCarbon, %IR - GravimetricCarbon, %B 1.205 1.30 0.095A 3.122 3.17 0.048C 6.551 6.57 0.019D 10.512 10.51 0.002E 15.112 15.07 0.042F 19.712 19.60 0.112E 2050 99 (2004)4
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