1、Designation: E2050 12aStandard Test Method forDetermination of Total Carbon in Mold Powders byCombustion1This standard is issued under the fixed designation E2050; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 covers the determination of totalcarbon in mold powders in the concentration range from 1 % to25 %.NOTE 1As
3、used in this test method, “percentage” or “%” refers to amass fraction of the form (wt / wt %) (g/100g).1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This test method has been evaluated in accordance withPractice E1601
4、 and Guide E1763. Unless otherwise noted inthe precision and bias section, the lower limit in the scope ofeach method specifies the lowest analyte content that may beanalyzed with acceptable error (defined as a nominal 5 % riskof obtaining a 50 % or larger relative difference in results onthe same t
5、est sample in two laboratories).1.4 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 limitati
6、ons prior to use.2. Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE135 Terminology
7、Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE882 Guide for Accountability and Quality Control in theChemical Analysis LaboratoryE1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, and Oxygen in Steel, Iron, Nickel, and CobaltAlloys by Various Combustion and Fu
8、sion TechniquesE1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical MethodE1763 Guide for Interpretation and Use of Results fromInterlaboratory Testing of Chemical Analysis Methods3. Terminology3.1 DefinitionsFor definitions of terms used in this testmet
9、hod, refer to Terminology E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 mold powder, 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
10、surface to preventunwanted solidification.3.2.1.1 DiscussionKey chemical components of thesepowders 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
11、-tion in a stream of oxygen. Full conversion of carbon monox-ide to carbon dioxide occurs by the passage of sample gasesthrough a catalytic heater assembly. The amount of carbon1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Mate
12、rials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved June 1, 2012. Published July 2012. Originally approvedin 1999. Last previous edition approved in 2012 as E205012. DOI: 10.1520/E2050-12A.2For referenced A
13、STM 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
14、hocken, PA 19428-2959, United States.dioxide 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 determination of total carbon inmold powde
15、rs 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 that the work will be performedin a proper
16、ly equipped laboratory and that proper wastedisposal procedures will be followed. Appropriate qualitycontrol practices must be followed such as those described inGuide E882.6. Rounding Calculated Values6.1 Calculated values shall be rounded in accordance withPractice E29.7. Interferences7.1 Halogens
17、, normally present in mold powders as fluoride,will interfere with this test method. A halogen trap, asdescribed in 8.4, must be installed in the measure line betweenthe furnace and analyzer to prevent this interference.8. Apparatus8.1 Combustion-Infrared Absorption Carbon Analyzer,equipped with a c
18、ombustion chamber, oxygen carrier stream,halogen trap, catalytic heater assembly, and infrared absorptiondetector, suitable for the analysis of carbon from 1 % to 25 %in mold powders. Instruments, such as those in Test MethodsE1019, which can be shown to give equivalent results may alsobe used for t
19、his test method.8.2 CruciblesUse ceramic crucibles that meet or exceedthe specifications of those recommended by the manufacturerof the instrument.8.3 Crucible Tongs, capable of handling recommended cru-cibles.8.4 Halogen (Fluorine/Chlorine) Trap3, available from theinstrument manufacturer as a kit,
20、 consisting of the parts andnecessary reagents for assembly. Follow the manufacturersinstructions for the assembly, installation, use, and propermaintenance of the trap.8.5 Metal Scoop, for dispensing metal chips.9. Reagents and Materials9.1 Iron Chip, high purity (6 mesh to +20 mesh).9.2 Oxygen, 99
21、.5 % purity recommended. Other grades ofoxygen may be used if low and consistent blank readings areobtained.9.3 Tungsten/Tin Accelerator, high purity.NOTE 2Copper chip accelerator (20 mesh to +30 mesh) may be usedin place of Tungsten/Tin.10. Hazards10.1 For precautions to be observed in the use of r
22、eagentsand apparatus in this method, refer to Practices E50 and TestMethods E1019.10.2 Use care when handling hot crucibles and whenoperating furnaces to avoid personal injury by either burn orelectrical shock.11. Sampling and Sample Preparation11.1 Materials SafetySamples must be prepared, stored,a
23、nd disposed of in accordance with the materials and safetyguidelines in Practices E50.11.2 Prepared SamplePulverize or grind the laboratorysample until 100 % passes a No. 100 (150-m) sieve. Store ina suitable glass or plastic container.12. Preparation of Apparatus12.1 Test the furnace and analyzer t
24、o ensure the absence ofleaks. Prepare the analyzer for operation in accordance with themanufacturers instructions.13. Calibration13.1 Calibration Reference MaterialsTungsten carbide(6.10 % total carbon), NIST SRM 276b, or equivalent; siliconcarbide (29.43 % total carbon), NIST SRM 112b, or equivalen
25、t(Note 1).13.2 Determination of Blank:13.2.1 Enter 1.000-g weight into the weight stack, followingthe instrument manufacturers recommended procedure.13.2.2 Add 1.000 6 0.005 g of accelerator and 1.000 60.005 g of iron chip to the crucible.13.2.3 Place the crucible on the furnace pedestal and ana-lyz
26、e in accordance with the manufacturers instructions.13.2.4 Repeat 13.2.1-13.2.3 a minimum of three times.3Fluorine/Chlorine Trap Kits, available from the LECO Corp., 3000 LakeviewAvenue, St. Joseph, Michigan 49085, +1-269-982-5497, http:/ havebeen found satisfactory for this purpose. Part number 769
27、-741-HAZ (for olderLECO instruments) and Part number 617-249-HAZ (for newer LECO instruments)were available on 01 April 2011.TABLE 1 Statistical Information, Carbon Combustion/Infrared MethodTest Material Number ofLaboratoriesCarbon Found, % Minimum SD (SM,E1601)Reproducibility SD,(Sg, E1601)Reprodu
28、cibility Index(R, E1601)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 29.4250 0.38830 0.60179 1.6850
29、 5.73E2050 12a213.2.5 Enter the average blank following the routine out-lined in the manufacturers instruction manual.13.3 Calibration Procedure:13.3.1 Weigh approximately 0.25 g of tungsten carbidecalibration reference material into a ceramic crucible and enterthe weight into the weight stack, foll
30、owing the instrumentmanufacturers recommended procedure.13.3.2 Add 1.000 g 6 0.005 g of accelerator and 1.000 g 60.005 g of iron chip to the crucible.13.3.3 Place the crucible on the furnace pedestal and ana-lyze in accordance with the manufacturers instructions.13.3.4 Repeat 13.3.1-13.3.3 a minimum
31、 of three times andcalibrate the instrument following the calibration procedure inaccordance with the manufacturers instruction manual.13.3.5 Verify the calibration by analyzing the calibrationreference material again. The obtained value shall agree withthe certificate value within the range given b
32、y the publisheduncertainty or it shall agree within the limits of a predictioninterval calculated using Eq 1. The prediction interval isdefined as the range of values bounded by the analysis value -pand the analysis value +p. If the prediction interval does notencompass the certified value, determin
33、e and correct the cause,and repeat calibration (Note 3). Either acceptance limit crite-rion is acceptable for routine operation.NOTE 3See the instrument manufacturers instructions concerning thetroubleshooting and correcting of errant calibration.p 5 t 3S1 11=nD3 s (1)where:p = one-half the predicti
34、on interval,n = number of replicates used in 13.3.4,t = students t chosen for the 95 % confidence level for nreplicate measurements (for example: t = 4.30 when n= 3; 3.18 when n = 4; 2.78 when n = 5), ands = standard deviation of n replicates in 13.3.4 (Note 4).NOTE 4Here, s should be comparable to
35、Sm, the repeatability standarddeviation, given in Table 1.Ifs much greater than Sm, there is evidencethat the repeatability of the particular instrument is not acceptable for usewith this test method. The user should determine and correct the cause,and repeat 13.3.4 through 13.3.5.13.3.6 Verify line
36、arity of the instrument response by ana-lyzing a silicon carbide certified (29.43 % total carbon) certi-fied reference material. Results should fall within the uncer-tainties of the certificate value expected tolerance. If not,identify and correct the problem before proceeding with theanalysis of sa
37、mples (Note 1).14. Procedure14.1 Assemble the apparatus and condition it in accordancewith Section 12.14.2 Sample Analysis:14.2.1 Weigh, to the nearest 0.1 mg, an appropriate mass ofsample into a ceramic crucible, in accordance with the follow-ing:Carbon, % Approximate Sample Mass, g1 - 6 0.256 - 10
38、 0.2010 - 20 0.1520 - 25 0.075Enter the sample mass into the mass stack, following theinstrument manufacturers recommended procedure.14.2.2 Add 1.000 g 6 0.005 g of accelerator and 1.000 g 60.005 g of iron chip to the crucible.14.2.3 Place the crucible on the furnace pedestal and ana-lyze.14.2.4 Ana
39、lyze each sample in duplicate, recording eachvalue.14.2.5 Check instrument calibration (see 13.3.5) after every2 sets of duplicate sample runs.15. Calculation15.1 Most commercially available instruments calculate thetotal carbon content directly, including corrections for blankand sample weight, so
40、calculations by the analyst are notrequired. If, however, the analyzer does not compensate forblank and sample values, then use the following formula:Carbon, % 5A B! 3 CD(2)where:A = DVM reading for sample,B = DVM reading for blank,C = weight compensator setting, andD = sample weight, g.15.2 Round t
41、he 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 % (Note 1).16. Precision and Bias416.1 PrecisionSeven laboratories cooperated in testingthis test method.Table 1 summarizes the prec
42、ision information.4A research report is available from ASTM International headquarters. RequestRR:E01-1029.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 0.329 3.320.0 0.645 3.2E2050 12a3Table 2 displays the repro
43、ducibility expected for results at anumber of carbon values.16.2 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 method with results on the same materials by thecombustion/gra
44、vimetric carbon test method. The differencesshow that the combined bias of both test methods does notexceed 60.1 % carbon (Note 1).17. Keywords17.1 carbon; combustion; infrared absorption spectrometry;mold powdersASTM International takes no position respecting the validity of any patent rights asser
45、ted 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
46、the 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 receiv
47、e 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 Intern
48、ational, 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
49、 the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).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 0.112E2050 12a4
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