1、Designation: C816 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 oforiginal adoption or, in the c
2、ase 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 of Defense.1. Scope*1.1 Th
3、is test method covers the determination of sulfur ingraphite in the concentration range from 1 g g to 1000 g g(ppm).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 standard does not purport to address all of thesafe
4、ty 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 prior to use.2. Referenced Documents2.1 ASTM Standards:2D3177 Test Methods for Total Sul
5、fur in the Analysis Sampleof Coal and Coke (Withdrawn 2012)3E50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated Materials3. Terminology3.1 Definitions:3.1.1 combustion, nchemical reaction by which graphiteis combined in a controlled man
6、ner with pure oxygen in a hightemperature furnace for analytical purposes.3.1.2 sulfur content, npercentage content by weight ofelemental sulfur present in graphite.3.1.3 titration, nquantitative chemical analysis methodused to determine the unknown concentration of a specifiedelement by reacting a
7、solution prepared from the sample to beanalyzed with a known concentration and volume of specificreagent.4. Summary of Test Method4.1 The sample is combusted with pure oxygen in a high-temperature furnace and a major portion of the sulfur isconverted to sulfur dioxide. The sulfur dioxide is passedth
8、rough a potassium iodide-starch solution where it is titratedwith potassium iodate solution. The potassium iodate solutionis standardized against samples of known sulfur content.5. Significance and Use5.1 Sulfur, even in very low concentrations, is of concern ina nuclear reactor because of potential
9、 corrosion of metalliccomponents. This test method has the sensitivity to analyzevery low sulfur contents in graphite using very small samples.5.2 This test method can be used to characterize graphite fordesign purposes.6. Interferences6.1 Any substance that releases volatile material, whichtends to
10、 enhance or to bleach the starch-iodine complex, willinterfere. Halogens and oxides of nitrogen interfere throughdarkening the color of the starch-iodine complex. Ultravioletlight will also darken the solution. A tube packed with eithersilver wool or antimony filings placed in the line between thefu
11、rnace and titration assembly will remove halogens from thegas stream.6.2 If the solution in the titration vessel becomes colorlessduring the titration, some SO2will be lost and a low result willbe obtained for the sulfur content.7. Apparatus7.1 Apparatus for the determination of sulfur by directcomb
12、ustion shall be in accordance with Practices E50.8. Reagents and Materials8.1 Potassium Iodate Solution (0.2 mM)Dissolve 44.4 mgof potassium iodate (KIO3) in water and dilute to 1 L.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants a
13、nd is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Dec. 1, 2015. Published January 2016. Originallyapproved in 1977. Last previous edition approved in 2010 as C816 85 (2010)1.DOI: 10.1520/C0816-15.2For referenced ASTM standards
14、, 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summ
15、ary 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 States1NOTE 1The sulfur equivalent for the KIO3solution is based on thefollowing reactions:KIO315KI16HCl 5 3I216KCl13H2OSO21I212H2O 5 H
16、2SO412HIOn the basis of 100 % conversion of sulfur to SO2, 1 mL of this solu-tion is equivalent to 20 g of sulfur.8.2 Hydrochloric AcidDilute 15 mL of concentrated hy-drochloric acid (HCl, sp gr 1.19) to 1 L with water.8.3 Starch-Potassium Iodide SolutionAdd 2 g of arrow-root starch to 50 mL of wate
17、r. Separately boil 150 mL of waterand slowly add the starch solution, stirring constantly. Cool,add 6 g of potassium iodide (KI), and pour the resultingsolution into a flask. Store in a refrigerator.8.4 Standard SulfurPrepare sulfur standards from cokesamples that have been analyzed by the Eschka Me
18、thod inaccordance with Test Method D3177.9. Procedure9.1 Adjust the furnace temperature to 1400 C to 1425 C.9.2 Turn on the oxygen and set the flow to 1 L 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 SO2titration vessel to th
19、e operating level withHCl solution.9.6 Add 2 mL of the starch-KI solution to the titrationvessel.9.7 Adjust the color of the solution in the titration vessel toa medium blue by additions of small amounts of KIO3solution.This color will be the color of the end point.NOTE 2If using a commercial sulfur
20、 titrator, follow the manufactur-ers instructions for its operation.9.8 Remove the stopper from the mouth of the combustiontube. Insert a boat containing a 0.2 g to 1.0 g sample into thecombustion tube and push into the hot zone.NOTE 3Furnace tubes used for high sulfur samples (above 1000 ppmS) shou
21、ld not be used for low sulfur samples. Separate furnace tubesshould be used for low and high sulfur samples.9.9 Replace the stopper sending the flow of oxygen throughthe combustion tube.9.10 Titrate the solution with the KIO3solution to maintainthe blue color developed in 9.7.9.11 When the combustio
22、n of the sample is complete,record the volume of KIO3solution used for the titration.9.12 Make a blank run on an empty prefired boat, ignitingfor the same length of time as the sample.9.13 Run standard sulfur samples to obtain a calibrationfactor. Place a weighed amount of the standard in a prefired
23、boat, ignite, and titrate following steps 9.9 to 9.12.10. Calculation10.1 Calculate the sulfur factor as follows:F 5 S/R 2 B!where: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).NOT
24、E 4Or substitute the apparent percentage of sulfur for “directreading” burets.10.2 Calculate the amount of sulfur in the test sample asfollows:Sulfur, ppm 5 T 2 B! 3 F#/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
25、= amount of sample, g.11. Precision and Bias11.1 The reproducibility among four laboratories was 14 %at the 9 ppm level and 4.2 % at the 86 ppm level.12. Keywords12.1 combustion; graphite; sulfur; titrationSUMMARY OF CHANGESSubcommittee D02.F0 has identified the location of selected changes to this
26、standard since the last issue(C816 85 (2010)1) 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.C816 152ASTM International takes no position respecting the validity of any patent rights asserted in
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29、ul 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 International
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