1、Designation: D 6120 97 (Reapproved 2007)An American National StandardStandard Test Method forElectrical Resistivity of Anode and Cathode Carbon Materialat Room Temperature1This standard is issued under the fixed designation D 6120; the number immediately following the designation indicates the year
2、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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the elec-tr
3、ical 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 This standard does not purport to address all of thesafety concerns, if any, associated wi
4、th 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 safetyinformation, see 8.2.3.2. Referenced Documents2.1 ASTM Standards:2C611 Test Method for Ele
5、ctrical Resistivity of Manufac-tured Carbon and Graphite Articles at Room TemperatureD 5502 Test Method for Apparent Density by PhysicalMeasurements of Manufactured Anode and Cathode Car-bon Used by the Aluminum Industry3. Terminology3.1 Definitions:3.1.1 electrical resistivity, nthe electrical resi
6、stance 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 carb
7、on 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 det
8、ermine 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
9、 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 resitivity may be selected as a require-ment in a customer specification.6. Apparatus
10、6.1 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 end
11、s 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 insulatig material with a minimum spacing of 50 mm anda maximum spacing of 80 % of the length of the specimen. Thedista
12、nce (L) in millimetres (mm) betweeen the center of theconical points or knife edges is used when calculating theelectrical resistivity.6.2 Apparatus for Indirect Resistance Measurement (per-mits measurement of voltage and current needed for calculat-ing electrical resistivity):1This test method is u
13、nder the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1997. Last previous editi
14、on approved in 2002 as D 6120 97 (2002).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
15、 in Chief, Dictionary of Scientific and Technical Terms,McGraw Hill Book Co., Fourth Ed., 1989, p 615.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2.1 dc Power SupplyThe power supply shall be capableof supplying a minimum DC cur
16、rent 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
17、, 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 devicecapable of measuring electrical resistance directly to0.01 milliohms such as a Kelvin bridge or a Micro-ohmmeter.These devices utilize 4wire co
18、nnections (current and voltage)and should not be confused with a volt-ohm-meter. The usualrange measured is from approximately 0.1 to 10 milliohms.6.4 Micrometer (or equivalent), capable of measuring thedimensions of a specimen to 0.01 mm.6.5 Desiccator, large enough to hold several test speciments(
19、7.4), filled to capacity with a desiccant such as anhydrouscalcium sulfate or equivalent.6.6 Core Drill, equipped with a diamond abrasive andcapable of producing a 50mm core sample.6.7 Refractory Saw, with a diamond blade.7. Preparation of Test SpecimenNOTE 1Specimens prepared for determination of d
20、ensity using TestMethod D 5502 are acceptable without further preparation.7.1 Drill a core of 50- mm (6 1.0- mm) diameter in the formof a right circular cylinder and use no lubricant having aboiling point above 100C.7.2 Cut a specimen from this core with a minimum length of120 mm.7.3 Ascertain by vi
21、sual inspection that all edges and faces ofthe specimen are free of chips or gouges. Ensure that thespecimen is free of residue from the coring and sawingoperations.7.4 Dry the specimen for a minimum of 2 h at 100C; thenallow to it to cool to 22 6 5C in a dessicator. Store thespecimen in a dessicato
22、r until immediately prior to testing.8. Procedure8.1 Test at 22 6 5C8.2 Indirect Resistance Measurement:8.2.1 Mount the test specimen in the holder and tightencontact plates firmly to the ends of the specimen.8.2.2 Apply voltage and adjust current to about6 amps 6 3A.8.2.3 Center the contact points
23、longitudinally on top of thisspecimen and measure the voltage drop. Move the contactpoints around the curcumference of the cylinder a distanceequivalent to an arc length of the circumference subtended bya 45 angle. Make sure contacts are still longitudinally centeredand take a voltage reading. Conti
24、nue moving in the samedirection around the circumference until a total of eight equallyspaced voltage readings are recorded. (WarningPassing acurrent through a test specimen for an extended period of timecan increase the temperature and consequently lower theresistance of the specimen.)8.3 Direct Re
25、sistance Measurement:8.3.1 Mount the test specimen in the holder and tightencontact plates firmly to the ends of the specimen.8.3.2 Center the contact points longitudinally on top of thespecimen and measure the resistance. Move the contact pointsaround the circumference of the cyinder a distance equ
26、ivalentto an arc length of the circumference subtended by 45 angle.Make sure contacts are still longitudinally centered and take aresistance reading. Continue moving in the same directionaround the circumference until a total of eight equally spacedresistance readings are recorded.NOTE 2The current
27、in the specimen when using a direct readingelectrical resistance measuring device (such as a Micro-ohmmeter) islower than when using an indirect resistance measurement device (about0.1 A versus 3 to 9 A).8.4 Measuring Specimen Diameter:8.4.1 Make two sets of four diameter measurements inmillimetres
28、using a micrometer or similar instrument. For thefirst set record the diameter at both ends and at two equidistantintermediate points along the same plane cutting through theaxis. Rotate the plane 90 and record an equivalent set of fourreadings (Fig. 2).8.4.2 Determine the quadratic mean diameter us
29、ing Eq 1.FIG. 1 Schematic of Specimen HolderFIG. 2 Measurement of Specimen DiameterD 6120 97 (2007)2d 581d1211d221 11d82(1)where:d = quadratic mean diameter, mm, andd1,d2, d8= individual diameter measurements, mm.9. Calculation of Resistivity9.1 Average the eight voltage readings from 8.2.3 or theei
30、ght resistance readings from 8.3.2.9.2 Calculate the cross-sectional area using Eq 2:A 5p3d24(2)where:A = cross-sectional area, mm2,p = 3.1416, andd = quadratic mean diameter, mm (8.4.2).9.3 If the indirect resistance measurement method (8.2) wasused, calculate electrical resistivity using Eq 3:ER 5
31、V 3 AI 3 L(3)where:ER = electrical resistivity, Vm,V = average voltage drop, mV (9.1),A = cross-sectional area, mm2(9.2),L = distance between contact points, mm (6.1.1), andI = magnitude of electrical current, A (8.2.2).9.4 If the direct resistance measurement method (8.3) wasused, calculate electri
32、cal resistivity using Eq 4:ER 5AL3 R (4)where:ER = electrical resistivity, Vm),A = cross-sectional area, mm2(9.2),L = distance between contact points, mm (6.1.1), andR = average electrical resistance, milliohms (9.1).10. Report10.1 Report the following information:10.1.1 Electrical resistivity to 0.
33、1 microohmmeter.11. Precision and Bias11.1 The criteria in 11.1.1 and 11.1.2 shall be used forjudging the acceptability of results (95 % probability) obtainedusing a current between 0.1 and 9 amps and in the electricalresistivity range from 12 to 80 Vm. Based upon a roundrobin testing program4using
34、duplicate measurement of 12samples at 8 laboratories, the following equations represent theexpected behavior for these tests.11.1.1 RepeatabilityThe difference between successiveresults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materia
35、lwould, in the long run, exceed the following values only in onecase in twenty.Repeatability 5 0.1780 3 =x (5)where x = average of the successive results in Vm.11.1.2 ReproducibilityThe difference between single andindependent results obtained by different operators workin indifferent laboratories o
36、n identical test material would, in thelong run, exceed the following values only in one case intwentyReproducibility 5 0.6535 3 =x (6)where x = average of the two results in Vm.11.2 BiasBias of this test method for measuring electricalresistivity has not been determined because, currently, allmetho
37、ds are based on electrical resistance measured within theparameters given in this test method.12. Keywords12.1 anode; cathode; cathode carbon; conductivity; electri-cal resistivity; resistivityASTM International takes no position respecting the validity of any patent rights asserted in connection wi
38、th any item mentionedin this standard. Users of this standard are expressly advised that determination of the 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 tech
39、nical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your 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 considerat
40、ion 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, 100 Barr Ha
41、rbor 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).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D021414.D 6120 97 (2007)3
