1、Designation: E2050 12aE2050 17Standard 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
2、 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 covers the determination of total carbon in mold powders in the concentration range from 1 % to 25 %
3、.NOTE 1As used in this test method, “percentage” or “%” refers to a mass fraction of the form (wt / wt %) (g/100g).1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This test method has been evaluated in accordance with
4、Practice E1601 and Guide E1763. Unless otherwise noted in theprecision and bias section, the lower limit in the scope of each method specifies the lowest analyte content that may be analyzedwith acceptable error (defined as a nominal 5 % risk of obtaining a 50 % or larger relative difference in resu
5、lts on the same testsample in two laboratories).1.4 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 this standard to establish appropriate safety and health practices and determine the applicability of regu
6、latorylimitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organi
7、zation Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE50 Practices forApparatus, Reagents, and Safety Considerations for ChemicalAnalysis of Metals, Ores, and R
8、elated MaterialsE135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related MaterialsE882 Guide for Accountability and Quality Control in the Chemical Analysis LaboratoryE1019 Test Methods for Determination of Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobal
9、t Alloys byVarious Combustion and Fusion TechniquesE1601 Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical MethodE1763 Guide for Interpretation and Use of Results from Interlaboratory Testing of Chemical Analysis Methods (Withdrawn2015)33. Terminology3.1 D
10、efinitionsFor definitions of terms used in this test method, refer to Terminology E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 mold powder, n in the continuous-casting of steel, a metallurgical flux used to provide lubrication of the mold, enhanceheat transfer at the strand-mold int
11、erface, and provide thermal insulation of the liquid metal surface to prevent unwantedsolidification.3.2.1.1 Discussion1 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 E0
12、1.02 on Ores, Concentrates, and Related Metallurgical Materials.Current edition approved June 1, 2012April 1, 2017. Published July 2012June 2017. Originally approved in 1999. Last previous edition approved in 2012 asE205012.12a. DOI: 10.1520/E2050-12A.10.1520/E2050-17.2 For referencedASTM standards,
13、 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 The last approved version of this historical standard is referenced on www.astm.org.This d
14、ocument is not an ASTM standard and is intended only to provide the user of an ASTM standard an 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
15、as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Key chemical components of these powders are fluorides
16、, the oxides of silicon and calcium, and carbon.4. Summary of Test Method4.1 Carbon in the test sample is converted in a furnace to a mixture of carbon dioxide (CO2) and carbon monoxide (CO) bycombustion in a stream of oxygen. Full conversion of carbon monoxide CO to carbonCO2 dioxide occurs by the
17、passage of samplegases through a catalytic heater assembly. The amount of carbonCO2 dioxide is measured by infrared absorption.Any interferencefrom halogens in the sample is eliminated by placement of a halogen trap between the furnace and the analyzer.5. Significance and Use5.1 This test method for
18、 the determination of total carbon in mold powders is primarily intended to test such materials forcompliance with compositional specifications. It is assumed that all who use this test method will be trained analysts capable ofperforming common laboratory procedures skillfully and safely. It is exp
19、ected that the work will be performed in a properlyequipped laboratory and that proper waste disposal procedures will be followed. Appropriate quality control practices must befollowed such as those described in Guide E882.6. Rounding Calculated Values6.1 Calculated values shall be rounded in accord
20、ance with Practice E29.7. Interferences7.1 Halogens, normally present in mold powders as fluoride, will interfere with this test method. A halogen trap, as describedin 8.4, must be installed in the measure line between the furnace and analyzer to prevent this interference.8. Apparatus8.1 Combustion-
21、Infrared Absorption Carbon Analyzer, equipped with a combustion chamber, oxygen carrier stream, halogentrap, catalytic heater assembly, and infrared absorption detector, suitable for the analysis of carbon from 1 %1 to 25 % in moldpowders. Instruments, such as those in Test Methods E1019, which can
22、be shown to give equivalent results may also be used forthis test method.8.2 CruciblesUse ceramic crucibles that meet or exceed the specifications of those recommended by the manufacturer of theinstrument.8.3 Crucible Tongs, capable of handling recommended crucibles.8.4 Halogen (Fluorine/Chlorine) T
23、rap, ,available from the instrument manufacturer as a kit, consisting of the parts andnecessary reagents for assembly. Follow the manufacturers instructions for the assembly, installation, use, and proper maintenanceof the trap.8.5 Metal Scoop, for dispensing metal chips.chips (accelerators).9. Reag
24、ents and Materials9.1 Iron Chip, high purity (6 mesh to +20 mesh).purity.9.2 Oxygen, 99.5 % purity recommended. Other grades of oxygen may be used if low and consistent blank readings areobtained.9.3 Tungsten/Tin or Copper Accelerator, high purity.NOTE 2Copper chip accelerator (20 mesh to +30 mesh)
25、may be used in place of Tungsten/Tin.10. Hazards10.1 For precautions to be observed in the use of reagents and apparatus in this method, refer to Practices E50 and Test MethodsE1019.10.2 Use care when handling hot crucibles and when operating furnaces to avoid personal injury by either burn or elect
26、ricalshock.11. Sampling and Sample Preparation11.1 Materials SafetySamples must be prepared, stored, and disposed of in accordance with the materials and safetyguidelines in Practices E50.11.2 Prepared SamplePulverize or grind the laboratory sample until 100 % passes a No. 100 (150-m) sieve. Store i
27、n asuitable glass or plastic container.E2050 17212. Preparation of Apparatus12.1 Test the furnace and analyzer to ensure the absence of leaks. Prepare the analyzer for operation in accordance withasdirected in the manufacturers instructions.13. Calibration13.1 Calibration Reference MaterialsTungsten
28、 carbide (6.10 % total carbon), NIST SRM 276b, or equivalent; silicon carbide(29.43 % total carbon), NIST SRM 112b, or equivalent (certified for total carbon in the vicinity of 6.1 % C and silicon carbidecertified for total carbon in the vicinity of 29.4 %Note 1). C.NOTE 1As originally approved, thi
29、s standard relied on National Institute of Standards and Technology SRM 276b Tungsten Carbide and SRM 112bSilicon Carbide as calibration materials. Those SRMs have been discontinued. Certified reference materials are available from other sources.13.2 Determination of Blank:13.2.1 Enter 1.000-g weigh
30、t into the weight stack, following the instrument manufacturers a specific mass (for example, 1.0g) into the software, as it is recommended by the instrument manufacturer, and follow the recommended procedure.13.2.2 Add 1.000 6 0.005 g of accelerator and 1.000 6 0.005 g of iron chip to the crucible.
31、accelerators to the crucible. Typeand amount of accelerators depend on sample matrix. Optimum parameters are recommended by the instrument manufacturer.Some manufacturers provide scoops that dispense a specific amount of accelerator. Once it is verified that the scoop delivers thisapproximate mass,
32、it is acceptable to use this device for routine dispensing of accelerator.13.2.3 Place the crucible on the furnace pedestalposition and analyze in accordance with the manufacturers instructions.13.2.4 Repeat 13.2.1 13.2.3 a minimum of three times.13.2.5 Enter the average blank following the routine
33、outlined in the manufacturers instruction manual.13.3 Calibration Procedure:13.3.1 Weigh approximately Transfer 0.25 g of tungsten carbide calibration reference material material, weighed to the nearest1 mg, into a ceramic crucible and enter the weightmass into the weight stack, software, following
34、the instrument manufacturersrecommended procedure.13.3.2 Add 1.000 g 6 0.005 g of accelerator and 1.000 g 6the same type and amount of accelerators, which are used in13.2.20.005 g of iron chip , to the crucible.13.3.3 Place the crucible on the furnace pedestalposition and analyze in accordance witha
35、s directed in the manufacturersinstructions.13.3.4 Repeat 13.3.1 13.3.3 a minimum of three times and calibrate the instrument following the calibration procedure inaccordance withas directed in the manufacturers instruction manual.13.3.5 Verify the calibration by analyzing the calibration reference
36、material again. The obtained value shall agree with thecertificate value within the range given by the published uncertainty or it shall agree within the limits of a prediction intervalcalculated using Eq 1. The prediction interval is defined as the range of values bounded by the analysis value -p a
37、nd the analysisvalue +p. If the prediction interval does not encompass the certified value, determine and correct the cause, and repeat calibration(Note 32). Either acceptance limit criterion is acceptable for routine operation.NOTE 2See the instrument manufacturers instructions concerning the troub
38、leshooting and correcting of errant calibration.p 5t 3S11 1=nD3s (1)where:p = one-half the prediction interval,p = magnitude of the one-sided, prediction interval,n = number of replicates used in 13.3.4,TABLE 1 Statistical Information, Carbon Combustion/Infrared MethodTest Material Number ofLaborato
39、riesCarbon Found, % Minimum SD(SM,E1601)Reproducibility SD,(Sg,E1601)Reproducibility 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 2.7
40、3F 7 19.7121 0.11949 0.25294 0.70824 3.59G 7 29.4250 0.38830 0.60179 1.6850 5.73E2050 173t = students t chosen for the 95 % confidence level for n replicate measurements (for example:t = 4.30 when n = 3; 3.18 whenn = 4; 2.78 whenn = 5), andt = students t variate chosen for a one-sided interval at th
41、e 95 % confidence level for degrees of freedom df = (n 1); a tablemay list this variate as t.95. The values are:t = 2.92 for n = 3 (df = 2)t = 2.35 for n = 4 (df = 3)t = 2.13 for n = 5 (df = 4)s = standard deviation of n replicates in 13.3.4 (Note 4).s = standard deviation of n replicates in 13.3.4
42、(Note 3).NOTE 3Here, s should be comparable to Sm, the repeatability standard deviation, given in Table 1. If s much greater than Sm, there is evidence thatthe repeatability of the particular instrument is not acceptable for use with this test method. The user should determine and correct the cause,
43、 and repeat13.3.4 through 13.3.5.13.3.6 Verify linearity of the instrument response by analyzing a silicon carbide certified (29.43 % total carbon) certifiedreference material. Results should fall within the uncertainties of the certificate value expected tolerance. If not, identify and correctthe p
44、roblem before proceeding with the analysis of samples (samples.Note 1).14. Procedure14.1 Assemble the apparatus and condition it in accordance withas directed in Section 12.14.2 Sample Analysis:14.2.1 Weigh, to the nearest 0.1 mg, an appropriate mass of sample into a ceramic crucible, in accordance
45、with the following:as follows:Carbon, % Approximate Sample Mass, g1 - 6 0.256 - 10 0.2010 - 20 0.1520 - 25 0.075Enter the sample mass into the mass stack, software, following the instrument manufacturers recommended procedure.14.2.2 Add 1.000 g 6 0.005 g of accelerator and 1.000 g 6 0.005 g of iron
46、chip to the crucible.crucible (see 13.2.2).14.2.3 Place the crucible on the furnace pedestalposition and analyze.14.2.4 Analyze each sample in duplicate, recording each value.14.2.5 Check instrument calibration (see 13.3.5) after every 2two sets of duplicate sample runs.15. Calculation15.1 Most comm
47、ercially available instruments calculate the total carbon content directly, including corrections for blank andsample weight,mass, so calculations by the analyst are not required. If, however, the analyzer does not compensate for blank andsample values, then use the following formula:Carbon,%5A 2B!3
48、CD (2)where:A = DVM reading for sample,A = instrument reading for sample,B = DVM reading for blank,B = instrument reading for blank,C = weight compensator setting, andD = sample weight, g.15.2 Round the results and report to 2two decimal places for values less than 10 % carbon, and to 1one decimal p
49、lace for valuesequal to or greater than 10 % carbon. Examples: 4.15 %, 15.6 % (15.6 %.Note 1).16. Precision and Bias416.1 PrecisionSeven laboratories cooperated in testing this test method. Table 1 summarizes the precision information. Table2 displays the reproducibility expected for results at a number of carbon values.4 A research report is available from ASTM International headquarters. Request RR:E01-1029.E2050 17416.2 BiasThe accuracy of this test method could not be evaluated because certified reference materials of mold powders wereun
