1、Designation:C81615An 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 case o
2、f 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 This test meth
3、od 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 thesafety concerns,i
4、f 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 Sulfur in theAnalysi
5、s Sampleof Coal and Coke(Withdrawn 2012)3E50 Practices for Apparatus,Reagents,and Safety Consid-erations for Chemical Analysis of Metals,Ores,andRelated Materials3.Terminology3.1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 manner with pure oxygen in a
6、 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 solution prepared from the
7、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 passedthrough a potassium iodide-star
8、ch 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 corrosion of metalliccomponents.
9、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 enhance or to bleach the starch-iod
10、ine 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 thefurnace and titration assembly will remove
11、 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 directcombustion shall be in accordance with Practic
12、es 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 and is the direct responsibility ofSubcommittee D
13、02.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,visit the ASTM website,www.astm.org,orcontact ASTM Cus
14、tomer 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 Summary of Changes section appears at the end of this standardCo
15、pyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE1The sulfur equivalent for the KIO3solution is based on thefollowing reactions:KIO315KI16HCl5 3I216KCl13H2OSO21I212H2O 5 H2SO412HIOn the basis of 100%conversion of sulfur to SO2,1 mL of th
16、is 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 water.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 ana
