1、Designation: D6120 97 (Reapproved 2017)1Standard 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.1NOTEUnits formatting was corrected editorially in February 2017.1. Scope1.1 This test method cover
3、s 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 asstand
4、ard. 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 appli
5、ca-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-surement
6、s 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 reciproc
7、al 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
8、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-fact
9、s 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 ana
10、node/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
11、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 sha
12、pe and securely fastened torigid insulating material with a minimum spacing of 50 mmand a maximum spacing of 80 % of the length of the specimen.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubc
13、ommittee D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved Jan. 1, 2017. Published February 2017. Originallyapproved in 1997. Last previous edition approved in 2012 as D6120 97 (2012).DOI: 10.1520/D6120-97R17E01.2For referenced ASTM standards, visit the ASTM
14、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
15、., 1989, p 615.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevel
16、opment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1The distance (L) in millimetres (mm) between the center of theconical points or knife edges is used when calculating theelectrical resistivity.6.2 Apparat
17、us 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 A at an electricalpotential of up to 5 V. The line and load regulation shall b
18、e 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 A to 0.01 A.6.3 Apparatus for Direct Resistan
19、ce Measurement:6.3.1 Electrical Resistance Measuring DeviceA devicecapable of measuring electrical resistance directly to 0.01 msuch as a Kelvin bridge or a Micro-ohmmeter. These devicesutilize 4-wire connections (current and voltage) and should notbe confused with a volt-ohm-meter. The usual range
20、measuredis from approximately 0.1 m to 10 m.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 specimens(7.4), filled to capacity with a desiccant such as anhydrouscalcium sulfate or equivalent.6.6 Core Drill,
21、 equipped with a diamond abrasive andcapable of producing a 50 mm core sample.6.7 Refractory 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
22、.0 mm) diameter in the formof a right circular cylinder and use no lubricant having aboiling point above 100 C.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 thespeci
23、men is free of residue from the coring and sawingoperations.7.4 Dry the specimen for a minimum of 2 h at 100 C; thenallow to it to cool to 22 C 6 5 C in a dessicator. Store thespecimen in a dessicator until immediately prior to testing.8. Procedure8.1 Test at 22 C 6 5 C.8.2 Indirect Resistance Measu
24、rement: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 about 6 A 6 3A.8.2.3 Center the contact points longitudinally on top of thisspecimen and measure the voltage drop. Move the contactpoints around t
25、he circumference 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. Continue moving in the samedirection around the circumference until a total of eight equallyspaced volta
26、ge 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 Resistance Measurement:8.3.1 Mount the test specimen in the holder and tightencontact plates firmly t
27、o 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 cylinder a distance equivalentto an arc length of the circumference subtended by 45 angle.Make sure contacts are still lo
28、ngitudinally 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 in the specimen when using a direct readingelectrical resistance measuring device (such as a Micro
29、-ohmmeter) islower than when using an indirect resistance measurement device (about0.1 A versus 3 A 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
30、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 using Eq 1.d 5!81d1211d22111d82(1)where:d = quadratic mean diameter, mm, andd1,d2, d8= individual
31、diameter measurements, mm.FIG. 1 Schematic of Specimen HolderD6120 97 (2017)129. Calculation 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, =
32、 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 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 be
33、tween 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 electrical resistivity using Eq 4:ER 5AL3 R (4)where:ER = electrical resistivity, m),A = cross-sectional area, mm2(9.2),L = distance between co
34、ntact 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 0.1 m.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)
35、 obtainedusing a current between 0.1 A and 9 A and in the electricalresistivity range from 12 mto80 m. Based upon around robin testing program4using duplicate measurement of12 samples at 8 laboratories, the following equations representthe expected behavior for these tests.11.1.1 RepeatabilityThe di
36、fference between successiveresults obtained by the same operator with the same 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 resul
37、ts in m.11.1.2 ReproducibilityThe difference between single andindependent results 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 = avera
38、ge of the two results in m.11.2 BiasBias of this test method for measuring electricalresistivity 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; conducti
39、vity; electri-cal resistivity; resistivityASTM 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 validity of any such patent rights, and t
40、he 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 comments are invited either for revision
41、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 have not received a fair hearing you shoul
42、dmake 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 obtain
43、ed 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1414. ContactASTM CustomerService at serviceastm.org.FIG. 2 Measurement of Specimen DiameterD6120 97 (2017)13
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