ASTM_D_6120_-_97_2012.pdf

Designation:D612097(Reapproved 2012)Standard Test Method forElectrical Resistivity of Anode and Cathode Carbon Materialat Room Temperature1This standard is issued under the fixed designation D6120;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 at room temperature of solid cylindricalspecimens cored from commercial sized carbon anodes andcathodes.This test method also applies to samples from carbonblocks prepared in a laboratory.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 limitation prior to use.For specific warninginformation,see.2.Referenced Documents2.1 ASTM Standards:2C611 Test Method for Electrical Resistivity of ManufacturedCarbon and Graphite Articles at Room TemperatureD5502 Test Method for Apparent Density by Physical Mea-surements of Manufactured Anode and Cathode CarbonUsed by the Aluminum Industry3.Terminology3.1 Definitions:3.1.1 electrical resistivity,nthe electrical resistance of-fered by a material to the flow of current,times the cross-sectional area of current flow and per unit length of currentpath,the reciprocal of conductivity.It is also known asresistivity,or specific resistance.34.Summary of Test Method4.1 An electrical current is passed through a carbon cylinderand the voltage drop or electrical resistance is measuredbetween two points along its length.The resistivity is calcu-lated based on the voltage drop or electrical resistance,distancebetween the two points,and the cross-sectional area of thecylinder.4.2 This test method are used to determine electrical resis-tivity for various carbon materials typically found in thealuminum industry.Electrical resistivity of other carbon arti-facts such as graphite and specialty carbons is more appropri-ately determined by Test Method C611.5.Significance and Use5.1 The electrical resistivity of anode and cathode carbonmaterial is important for efficient aluminum cell operation.It isa quality parameter that determines the suitability of ananode/cathode for operation in an aluminum cell.5.2 The electrical resistivity may be selected as a require-ment in a customer specification.6.Apparatus6.1 Specimen Holder(Fig.1),a device for holding aspecimen of 50 mm diameter and a minimum of 120 mm inlength between two flat copper plates.One of the plates isswivel mounted to ensure good contact in case the ends of thespecimen are not perfectly parallel.The plates shall be as largeas the ends of the specimen and electrically insulated from eachother.6.1.1 Voltage Drop Contact PointsThe contact pointsshall be conical or knife edge in shape and securely fastened torigid insulating material with a minimum spacing of 50 mmand a maximum spacing of 80%of the length of the specimen.The distance(L)in millimetres(mm)between the center of theconical points or knife edges is used when calculating theelectrical resistivity.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.05 on Properties of Fuels,Petroleum Coke and Carbon Material.Current edition approved Nov.1,2012.Published December 2012.Originallyapproved in 1997.Last previous edition approved in 2007 as D6120 97(2012).DOI:10.1520/D6120-97R12.2For 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 Document Summary page onthe ASTM website.3Parker,Sybil P.,Ed in Chief,Dictionary of Scientific and Technical Terms,McGraw Hill Book Co.,Fourth Ed.,1989,p 615.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 Apparatus for Indirect Resistance Measurement(permits measurement of voltage and current needed forcalculating electrical resistivity):6.2.1 dc Power SupplyThe power supply shall be capableof supplying a minimum dc current of 10 amps at an electricalpotential of up to 5 V.The line and load regulation shall be lessthan 0.1%and background noise less than or equal to 0.1%.6.2.2 dc Voltage Measuring Instrument,high-impedancedevice capable of measuring a minimum of 5 V to 0.01 mV.6.2.3 dc Current Measuring Device,a device capable ofmeasuring a current of 10 to 0.01 A.6.3 Apparatus for Direct Resistance Measurement:6.3.1 Electrical Resistance Measuring DeviceA