ASTM_C_611_-_98_2016.pdf

Designation:C61198(Reapproved 2016)An American National StandardStandard Test Method forElectrical Resistivity of Manufactured Carbon and GraphiteArticles at Room Temperature1This standard is issued under the fixed designation C611;the number immediately following the designation indicates the year oforiginal 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.1.Scope1.1 This test method covers the determination of the elec-trical resistivity of manufactured carbon and graphite articles atroom temperature.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,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.Terminology2.1 Definitions:2.1.1 resistivitythe property of a material that determinesits resistance to the flow of an electrical current.It is defined asthe value of,in milliohm metres,as follows:5RA!/Lwhere:R=resistance of a specimen of the material of uniform crosssection,ohms,A=uniform cross section,mm2,andL=distance between potential contacts,mm.3.Significance and Use3.1 This test method provides a means of determining theelectrical resistivity of carbon or graphite specimens.The useof specimens that do not conform to the specimen sizelimitations described in the test method may result in analteration of test method accuracy.4.Apparatus4.1 The means for applying current and potential terminalsto the specimen is specified in 5.2.3.1.A typical specimenholder is shown in Fig.1.4.2 Bridge,Potentiometer,or Suitable Digital Voltmeter,with necessary accessories for making resistance measure-ments with a limit of error of less than 0.5%.Fig.2schematically depicts two wiring diagrams that have beenfound satisfactory for this purpose.4.3 The means for measuring the dimensions of the speci-men should be adequate to determine its gage length and itsmean area of cross section,each within 0.5%.5.Test Specimen5.1 The test specimen may be in the form of a strip,rod,bar,or tube.5.2 In order to determine the resistivity,each specimen shallconform to the following:5.2.1 The cross-sectional area shall be uniform within0.75%.In general,the diameter of circular cross section,or thethickness and width of a strip specimen shall be determined bymicrometer measurements,and a sufficient number of mea-surements shall be made to obtain a mean cross-sectional areato within 0.5%.The test specimen shall be machined to yieldplanar and parallel end faces.These faces shall be perpendicu-lar to the specimen length to within 0.001 mm mm.Allsurfaces shall have a surface finish visually comparable to0.8 m rms.Reasonable care should be exercised to assure thatall edges are sharp and without chips or other flaws.5.2.2 The test specimen shall show no defects observablewith normal vision and shall be free of surface deposits.5.2.3 The minimum ratio of specimen length to maximumcross-sectional dimension(width or diameter)shall be 6:1.5.2.3.1 The gage length may be measured by any scale thatwill give an accuracy of 60.5%in the length measured.In thedirection of the length of the specimen,the dimension of eachpotential contact shall be not more than 0.5%of the distancebetween the potential contacts.The minimum distance betweeneach potential contact and the adjacent current contact shall bethe maximum cross-sectional dimension(width or diameter)ofthe specimen.If knife edges are used,they shall be parallel toeach other and perpendicular to the longitudinal direction ofthe sample.The minimum ratio of gage length to maximumcross-sectional dimension(width or diameter)shall be 4:1.5.2.4 No dimension shall be smaller than five times thelength of the largest visible particle.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Oct.1,2016.Published November 2016.Originallyapproved in 2005.Last previous edition approved in 2010 as C611 98(2010)1.DOI:10.1520/C0611-98R16.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2.5 No joints or splices are permissible,unless this is thevariable under study.6.Conditioning6.1 The specimen shall be dried for a minimum of 2 h at110 C,cooled to room temperature in a desiccator,and storedin a desiccator until tested.7.Procedure7.1 Resistance MeasurementMeasure resistance with in-struments accurate to 60.5%or less(see Note 1).To ensure acorrect reading,the reference standard and the test specimenmust be allowed to come t