1、Designation: C816 85 (Reapproved 2010)1C816 15 An American National StandardStandard Test Method forSulfur Content in Graphite by Combustion-IodometricTitration Method1This standard is issued under the fixed designation C816; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, 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
3、of Defense.1 NOTERemoved source of supply footnote and updated units of measurement throughout the standard editorially inMay 2010.1. Scope Scope*1.1 This test method covers the determination of sulfur in graphite in the concentration range from 11 gg to 10001000 gg/g g (ppm).1.2 The values stated i
4、n SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 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 this standard to establish appropriate safety and h
5、ealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3177 Test Methods for Total Sulfur in the Analysis Sample of Coal and Coke (Withdrawn 2012)3E50 Practices forApparatus, Reagents, and Safety Considerations for ChemicalAn
6、alysis of Metals, Ores, and Related Materials3. Terminology3.1 Definitions:3.1.1 combustion, nchemical reaction by which graphite is combined in a controlled manner with pure oxygen in a hightemperature furnace for analytical purposes.3.1.2 sulfur content, npercentage content by weight of elemental
7、sulfur present in graphite.3.1.3 titration, nquantitative chemical analysis method used to determine the unknown concentration of a specified elementby reacting a solution prepared from the sample to be analyzed with a known concentration and volume of specific reagent.4. Summary of Test Method4.1 T
8、he sample is burned in oxygen combusted with pure oxygen in a high-temperature furnace and a major portion of the sulfuris converted to sulfur dioxide. The sulfur dioxide is passed through a potassium iodide-starch solution where it is titrated withpotassium iodate solution. The potassium iodate sol
9、ution is standardized against samples of known sulfur content.5. Significance and Use5.1 Sulfur, even in very low concentrations, is of concern in a nuclear reactor because of potential corrosion of metalliccomponents. This test method has the sensitivity to analyze very low sulfur contents in graph
10、ite using very small samples.5.2 This test method can be used to characterize graphite for design purposes.1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufac
11、tured Carbon and Graphite Products.Current edition approved May 1, 2010Dec. 1, 2015. Published May 2010January 2016. Originally approved in 1977. Last previous edition approved in 20052010 asC816 85 (2005).(2010)1. DOI: 10.1520/C0816-85R10E01.10.1520/C0816-15.2 For referencedASTM standards, visit th
12、eASTM 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 document i
13、s 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 as approp
14、riate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United State
15、s16. Interferences6.1 Any substance that releases volatile material, which tends to enhance or to bleach the starch-iodine complex, will interfere.Halogens and oxides of nitrogen interfere through darkening the color of the starch-iodine complex. Ultraviolet light will alsodarken the solution. A tub
16、e packed with either silver wool or antimony filings placed in the line between the furnace and titrationassembly will remove halogens from the gas stream.6.2 If the solution in the titration vessel becomes colorless during the titration, some SO2 will be lost and a low result will beobtained for th
17、e sulfur content.7. Apparatus7.1 Apparatus for the determination of sulfur by direct combustion shall be in accordance with No. 13 in Fig. 13 of PracticesE50.8. Reagents and Materials8.1 Potassium Iodate Solution (0.2 mM)(0.2 mM)Dissolve 44.4 mg 44.4 mg of potassium iodate (KIO3) in water anddilute
18、to 1 L. 1 L.NOTE 1The sulfur equivalent for the KIO3 solution is based on the following reactions:KIO315KI16HCl53I216KCl13H2OSO21I212H2O5H2SO412HIOn the basis of 100 % conversion of sulfur to SO2, 1 mL 1 mL of this solution is equivalent to 20 g 20 g of sulfur.8.2 Hydrochloric AcidDilute 15 mL 15 mL
19、 of concentrated hydrochloric acid (HCl, sp gr 1.19) to 1 L 1 L with water.8.3 Starch-Potassium Iodide SolutionAdd 2 g 2 g of arrowroot starch to 50 mL 50 mL of water. Separately boil 150 mL150 mL of water and slowly add the starch solution, stirring constantly. Cool, add 6 g 6 g of potassium iodide
20、 (KI), and pour theresulting solution into a flask. Store in a refrigerator.8.4 Standard SulfurPrepare sulfur standards from coke samples that have been analyzed by the Eschka Method in accordancewith Test Method D3177.9. Procedure9.1 Adjust the furnace temperature to 14001400 C to 1425C.1425 C.9.2
21、Turn on the oxygen and set the flow to 11 L L/min. min.9.3 Fill the buret with the iodate solution.9.4 Rinse the titration vessel with HCl solution and drain.9.5 Fill the SO2 titration vessel to the operating level with HCl solution.9.6 Add 2 mL of the starch-KI solution to the titration vessel.9.7
22、Adjust the color of the solution in the titration vessel to a medium blue by additions of small amounts of KIO3 solution.This color will be the color of the end point.NOTE 2If using a commercial sulfur titrator, follow the manufacturers instructions for its operation.9.8 Remove the stopper from the
23、mouth of the combustion tube. Insert a boat containing a 0.20.2 g to 1.0 g 1.0 g sample intothe combustion tube and push into the hot zone.NOTE 3Furnace tubes used for high sulfur samples (above 1000 ppm 1000 ppm S) should not be used for low sulfur samples. Separate furnace tubesshould be used for
24、low and high sulfur samples.9.9 Replace the stopper sending the flow of oxygen through the combustion tube.9.10 Titrate the solution with the KIO3 solution to maintain the blue color developed in 8.79.7.9.11 When the combustion of the sample is complete, record the volume of KIO3 solution used for t
25、he titration.9.12 Make a blank run on an empty prefired boat, igniting for the same length of time as the sample.9.13 Run standard sulfur samples to obtain a calibration factor. Place a weighed amount of the standard in a prefired boat, ignite,and titrate following steps 8.99.9 to 8.129.12.10. Calcu
26、lation10.1 Calculate the sulfur factor as follows:F 5S/R 2B!C816 152where:F = sulfur factor,S = amount of sulfur in the standard, g,R = amount of titrant for the standard, mL, (Note 4), and,B = amount of titrant for the blank, mL, (Note 4).NOTE 4Or substitute the apparent percentage of sulfur for “d
27、irect reading” burets.10.2 Calculate the amount of sulfur in the test sample as follows:Sulfur,ppm5T 2 B! 3F#/Gwhere:T = amount of titrant for the sample, L, (Note 4),B = amount of titrant for the blank, mL, (Note 4),F = sulfur factor, andG = amount of sample, g.11. Precision and Bias11.1 The reprod
28、ucibility among four laboratories was 14 % at the 9-ppm9 ppm level and 4.2 % at the 86-ppm86 ppm level.12. Keywords12.1 combustion; graphite; sulfur; titrationSUMMARY OF CHANGESSubcommittee D02.F0 has identified the location of selected changes to this standard since the last issue(C816 85 (2010)1)
29、that may impact the use of this standard. (Approved Dec. 1, 2015.)(1) Revised the title.(2) Added new Terminology Section 3.(3) Revised subsection 4.1.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Use
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