1、Designation: C 816 85 (Reapproved 2005)An American National StandardStandard Test Method forSulfur in Graphite by Combustion-Iodometric TitrationMethod1This standard is issued under the fixed designation C 816; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope
3、1.1 This test method covers the determination of sulfur ingraphite in the concentration range from 1 to 200 g/g in a 1-gsample or 5 to 1000 g/g in a 0.2-g sample.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concern
4、s, 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:2D 3177 Test Method for Total Sulfur in the
5、Analysis Sampleof Coal and CokeE50 Practices for Apparatus, Reagents, and Safety Precau-tions for Chemical Analysis of Metals3. Summary of Test Method3.1 The sample is burned in oxygen and a major portion ofthe sulfur is converted to sulfur dioxide. The sulfur dioxide ispassed through a potassium io
6、dide-starch solution where it istitrated with potassium iodate solution. The potassium iodatesolution is standardized against samples of known sulfurcontent.4. Significance and Use4.1 Sulfur, even in very low concentrations, is of concern ina nuclear reactor because of potential corrosion of metalli
7、ccomponents. This test method has the sensitivity to analyzevery low sulfur contents in graphite using very small samples.4.2 This test method can be used to characterize graphite fordesign purposes.5. Interferences5.1 Any substance that releases volatile material, whichtends to enhance or to bleach
8、 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 thefurnace and titration a
9、ssembly will remove halogens from thegas stream.5.2 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.6. Apparatus6.1 Apparatus for the determination of sulfur by directcombustion shall be in ac
10、cordance with No. 13 in Fig. 13 ofPractices E50.37. Reagents and Materials7.1 Potassium Iodate Solution (0.0444 g/L)Dissolve0.0444 g of potassium iodate (KIO3) in water and dilute to 1 L.NOTE 1The sulfur equivalent for the KIO3solution is based on thefollowing reactions:KIO31 5KI 1 6HCl 5 3I21 6KCl
11、1 3H2OSO21 I21 2H2O 5 H2SO41 2HIOn the basis of 100 % conversion of sulfur to SO2, 1 mL of this solutionis equivalent to 20 g of sulfur.7.2 Hydrochloric AcidDilute 15 mL of concentrated hy-drochloric acid (HCl, sp gr 1.19) to 1 L with water.7.3 Starch-Potassium Iodide SolutionAdd2gofarrow-root starc
12、h to 50 mL of water. Separately boil 150 mL of water1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.F0 on Manufactured Carbon and Graphite Products.Current edition approved May 1, 2005. Publishe
13、d May 2005. Originallyapproved in 1977. Last previous edition approved in 1998 as C 816 85 (1998)e1.2For referenced ASTM 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 Do
14、cument Summary page onthe ASTM website.3The sole source of supply of the apparatus known to the committee at this timeis available from Laboratory Equipment Co., St. Joseph, MI. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments
15、 will receive careful consideration at a meeting of theresponsible technical committee1, which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and slowly add the starch solution, stirring constantly. Cool,add6gofpotass
16、ium iodide (KI), and pour the resultingsolution into a flask. Store in a refrigerator.7.4 Standard SulfurPrepare sulfur standards from cokesamples that have been analyzed by the Eschka Method inaccordance with Test Method D 3177.8. Procedure8.1 Adjust the furnace temperature to 1400 to 1425C.8.2 Tur
17、n on the oxygen and set the flow to 1 L/min.8.3 Fill the buret with the iodate solution.8.4 Rinse the titration vessel with HCl solution and drain.8.5 Fill the SO2titration vessel to the operating level withHCl solution.8.6 Add 2 mL of the starch-KI solution to the titrationvessel.8.7 Adjust the col
18、or 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 titrator, follow the manufactur-ers instructions for its operation.8.8 Remove the stopper from the mouth of the co
19、mbustiontube. Insert a boat containing a 0.2 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) should not be used for low sulfur samples. Separate furnace tubesshould be used for low and high sulfur samples.8.9 Repla
20、ce the stopper sending the flow of oxygen throughthe combustion tube.8.10 Titrate the solution with the KIO3solution to maintainthe blue color developed in 8.7.8.11 When the combustion of the sample is complete,record the volume of KIO3solution used for the titration.8.12 Make a blank run on an empt
21、y prefired boat, ignitingfor the same length of time as the sample.8.13 Run standard sulfur samples to obtain a calibrationfactor. Place a weighed amount of the standard in a prefiredboat, ignite, and titrate following steps 8.9 to 8.12.9. Calculation9.1 Calculate the sulfur factor as follows:F 5 S/
22、R2B!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).NOTE 4Or substitute the apparent percentage of sulfur for “directreading” burets.9.2 Calculate the amount of sulfur in the t
23、est sample asfollows:Sulfur, ppm 5 T2B! 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 = amount of sample, g.10. Precision and Bias10.1 The reproducibility among four laboratories was 14 %at the 9-ppm level and
24、 4.2 % at the 86-ppm level.11. Keywords11.1 combustion; graphite; sulfur; titrationASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the
25、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 the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your
26、comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments h
27、ave 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, 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 the ASTM website(www.astm.org).C 816 85 (2005)2
