1、Designation: D6120 97 (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
2、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 tempera
3、ture 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.
4、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 warn
5、inginformation, see 8.2.3.2. 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 Aluminu
6、m 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 specif
7、ic 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 tw
8、o 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-ate
9、ly 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 electr
10、ical 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
11、 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 m
12、inimum 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 onPetrol
13、eum Products and Lubricants and is the direct responsibility of SubcommitteeD02.05 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: 10.1
14、520/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
15、 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 States16.2 Apparatus for Indirect Resistance Measurement(permits measurement of voltage and current needed forcalcu
16、lating 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 I
17、nstrument, 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 devicecapable of measuring electric
18、al resistance directly to 0.01milliohms such as a Kelvin bridge or a Micro-ohmmeter. Thesedevices utilize 4wire connections (current and voltage) andshould not be confused with a volt-ohm-meter. The usual rangemeasured is from approximately 0.1 to 10 milliohms.6.4 Micrometer (or equivalent), capable
19、 of measuring thedimensions of a specimen to 0.01 mm.6.5 Desiccator, large enough to hold several test specimens(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 Re
20、fractory Saw, with a diamond blade.7. Preparation of Test SpecimenNOTE 1Specimens prepared for determination of density using TestMethod D5502 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
21、aboiling point above 100C.7.2 Cut a specimen from this core with a minimum length of120 mm.7.3 Ascertain by visual 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
22、a minimum of 2 h at 100C; thenallow to it to cool to 22 6 5C in a dessicator. Store thespecimen in a dessicator until immediately prior to testing.8. Procedure8.1 Test at 22 6 5C.8.2 Indirect Resistance Measurement:8.2.1 Mount the test specimen in the holder and tightencontact plates firmly to the e
23、nds of the specimen.8.2.2 Apply voltage and adjust current to about 6 amps 6 3A.8.2.3 Center the contact points longitudinally on top of thisspecimen and measure the voltage drop. Move the contactpoints around the circumference of the cylinder a distanceequivalent to an arc length of the circumferen
24、ce subtended bya 45 angle. Make sure contacts are still longitudinally centeredand take a voltage reading. Continue 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 extende
25、d period of timecan increase the temperature and consequently lower theresistance of the specimen.)8.3 Direct Resistance 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 thesp
26、ecimen and measure the resistance. Move the contact pointsaround the circumference of the cylinder a distance equivalentto 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 direction
27、around the circumference until a total of eight equally spacedresistance readings are recorded.NOTE 2The current 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
28、versus 3 to 9 A).8.4 Measuring Specimen Diameter:8.4.1 Make two sets of four diameter measurements inmillimetres 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
29、the plane 90 and record an equivalent set of fourreadings (Fig. 2).8.4.2 Determine the quadratic mean diameter using Eq 1.d 5!81d1211d22111d82(1)where:d = quadratic mean diameter, mm, andd1,d2, d8= individual diameter measurements, mm.FIG. 1 Schematic of Specimen HolderD6120 97 (2012)29. Calculation
30、 of Resistivity9.1 Average the eight voltage readings from 8.2.3 or theeight resistance readings from 8.3.2.9.2 Calculate the cross-sectional area using Eq 2:A 5 3 d24(2)where:A = cross-sectional area, mm2, = 3.1416, andd = quadratic mean diameter, mm (8.4.2).9.3 If the indirect resistance measureme
31、nt method (8.2) wasused, calculate electrical resistivity using Eq 3:ER 5V 3 AI 3 L(3)where:ER = electrical resistivity, m,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 t
32、he direct resistance measurement method (8.3) wasused, calculate electrical resistivity using Eq 4:ER 5AL3 R (4)where:ER = electrical resistivity, m),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
33、.1 Report the following information:10.1.1 Electrical resistivity to 0.1 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
34、 range from 12 to 80 m. Based upon a roundrobin testing program4using 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
35、apparatusunder constant operating conditions on identical test materialwould, 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 m.11.1.2 ReproducibilityThe difference between single andindependent resu
36、lts obtained by different operators working indifferent laboratories on identical test material would, in thelong run, exceed the following values only in one case intwenty.Reproducibility 5 0.6535 3 =x (6)where x = average of the two results in m.11.2 BiasBias of this test method for measuring elec
37、tricalresistivity has not been determined because, currently, allmethods 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
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39、is 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 comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Int
40、ernational Headquarters. Your comments will receive careful consideration 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
41、 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), 610-832-9
42、555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1414.FIG. 2 Measurement of Specimen DiameterD6120 97 (2012)3
