1、INTERNATIONAL STANDARD ISO 12987 First edition 2004-07-01 Reference number ISO 12987:2004(E) ISO 2004 Carbonaceous materials for the production of aluminium Anodes, cathodes blocks, sidewall blocks and baked ramming pastes Determination of the thermal conductivity using a comparative method Produits
2、 carbons utiliss pour la production de laluminium Anodes, cathodes blocs, blocs de faade et ptes de brasquage cuites Dtermination de la conductivit thermique temprature ambiante par une mthode comparativeISO 12987:2004(E) ii ISO 2004 All rights reserved PDF disclaimer This PDF file may contain embed
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7、se postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandISO 12987:2004(E) ISO 2004 All rights reserved iii Contents Page 1 Scope 1 2 Terms and definitions 1 3 Reagents and materials 2 4 Apparatus . 2 5 Sampling . 2
8、6 Procedure . 4 7 Calculation . 4 8 Precision . 4 9 Test report 5 Bibliography . 6ISO 12987:2004(E) iv ISO 2004 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inte
9、rnational Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison wi
10、th ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technic
11、al committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn t
12、o the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 12987 was prepared by Technical Committee ISO/TC 47, Chemistry, Subcommittee SC 7, Aluminium oxide, cryolite, alumini
13、um fluoride, sodium fluoride, carbonaceous products for the aluminium industry.ISO 12987:2004(E) ISO 2004 All rights reserved v Introduction Knowledge of the thermal conductivity of carbonaceous materials allows calculations of the heat transfer and losses in electrolysis cells vi INTERNATIONAL STAN
14、DARD ISO 12987:2004(E) ISO 2004 All rights reserved 1 Carbonaceous materials for the production of aluminium Anodes, cathodes blocks, sidewall blocks and baked ramming pastes Determination of the thermal conductivity using a comparative method 1S c o p e This International Standard specifies a metho
15、d for the determination of thermal conductivity of carbonaceous material in the temperature range of to . The typical range of thermal conductivity for these materials is to . This method can be used for other carbon materials, such as graphitized electrodes for other applications. 2 Terms and defin
16、itions For the purposes of this document, the following terms and definitions apply. 2.1 thermal conductivity material property, expressed in , obtained by determining the heat flow at a given temperature difference through a body with height and cross-sectional area as follows: (1) where is the hea
17、t flow, expressed in watts; is the temperature difference, expressed in kelvins; is the height, expressed in metres, of the body; is the cross-sectional area, expressed in square metres NOTE 1 For cylindrical test specimens: (2) where is the diameter of the test specimens, expressed in metres NOTE 2
18、 This temperature difference is compared to those obtained with reference specimens thereby allowing the determination of the thermal conductivity of the test specimen. 20 C6 0 C 2 W/(Km) 100 W/(Km) W/(Km) dQ dt hA = dQ dt 1 h A dQ dt h A A = d 2 4 dISO 12987:2004(E) 2 ISO 2004 All rights reserved 3
19、 Reagents and materials 3.1 Contact agent, for testing, consisting of Vaseline, glycerol or contact paste capable of improving the contact between the heads and the specimen. 3.2 Calibration specimens, which have been calibrated by a recognized calibration authority such as the producer of the equip
20、ment or a national standards body. Table 1 shows examples of reference materials for specimens to be calibrated by the producer of equipment or by national standards bodies. The thermal conductivity of these materials varies almost linearly with temperature over the range of to . 4 Apparatus 4.1 Typ
21、ical measuring device, schematically shown in Figure 1 and consisting of the following: 4.1.1 Lower head, as heat sink cooled to . 4.1.2 Thermostatically controlled device, capable of maintaining the water temperature at and a circulating rate of approximately . 4.1.3 Differential thermocouple. 4.1.
22、4 Suitable voltmeter. 4.1.5 Upper head, as heat source, heated to at least , preferentially , and accurate to . 4.1.6 Liquid thermostat, capable of maintaining the water temperature at , and a circulating rate of approximately , or electrical heating device maintaining the temperature of the upper h
23、ead at . 4.1.7 Clamping device, applying a minimum pressure of about and a cardanic suspension. 4.1.8 Insulating cylinder, to avoid heat loss. 4.2 Device for measuring dimensions, with error limit of , for example a vernier calliper as specified in ISO 6906 or a micrometer calliper as specified in I
24、SO 3611. 4.3 Straight edge. 5 Sampling Select test specimens in accordance with a suitable sampling scheme, for example using ISO 8007-1 or ISO 8007-2. Table 1 Examples of reference materials Material Thermal conductivityat Flint glass 1,4 High alloy steel 14 Bronze 65 Brass 110 Aluminium pure 235 2
25、0 C 100 C W/(Km) 20 C 99,9 % 20 C 0,1 C 20 C 0,02 C 10 l/min 40 C6 0 C 0,1 C 40 C 0,02 C 10 l/min 60 C 0,1 C 5 MPa 1%ISO 12987:2004(E) ISO 2004 All rights reserved 3 The diameter of the cylindrical test specimens shall be between and , the height shall be fromto and the end surfaces shall be plane.
26、The accuracy of the method is affected by the geometry of the test specimens. For high thermal conductivity materials, thinner and/or longer test specimens yield better results. For test specimens of height, the diameters in Table 2 have been found appropriate. The flatness of the end planes shall b
27、e better than , which can be checked by means of the straight edge (4.3). The test specimens shall be dried to constant mass. Key 1 lower head 2 water flowing through the lower head at and 3 differential thermocouple element 4 differential thermocouple element 5 insulating cylinder 6 test specimen 7
28、 differential thermocouple element 8 direction of heat flow 9 upper head 10 clamping pressure 11 heating element Figure 1 A typical device to perform the test shown schematically Table 2 Dimensions of test specimens Typical range of thermal conductivity Test specimen material Diameter a mm Up to 10
29、Anodes 50 Baked ramming paste 5 to 120 Cathodes 50 or 30 80 to 120 Graphite electrodes 20 to 30 a Height of test specimens . The larger diameters are chosen for anodes, baked ramming paste and cathodes due to their coarser grain structure. 20 C 0,1 C 10 l/min T 2 T 1 T 0 (p)=200 N 20 mm 50 mm 5mm 50
30、mm 20 mm 0,05 mm W/(Km) = 20 mmISO 12987:2004(E) 4 ISO 2004 All rights reserved 6 Procedure 6.1 Measurement of test specimen dimensions Measure the height ( ) and diameter ( ) of the test specimens. 6.2 Calibration Close the upper (4.1.5) and lower (4.1.1) heads. Heat the apparatus to the operating
31、temperature. When the temperatures of both heads are stable within , choose one or several calibration specimens with the same cross-section as the test specimens. A thin layer of contact agent (3.1) may be applied to both sample end faces. Separate the heads and centre the specimens between the hea
32、ds, close the heads on the specimen and apply and maintain a suitable pressure. When the reading of the differential thermocouple (4.1.3) is constant, record the thermoelectric voltage (4.1.4). The calibration curve (thermoelectric voltage as a function of ) can be determined from measurements of di
33、fferent calibration specimens with known thermal conductivity and dimensions (see DIN 51908). The thermoelectric voltage yields the quantity for any specimen. If an insulating cylinder is used for the measurement of the test specimens, this cylinder should be used for calibration, as well. 6.3 Measu
34、rement of test specimens Test specimens with the same cross-sections as the calibration specimens are measured according to the measuring procedure given for calibration specimens in 6.2. 7 Calculation The thermal conductivity , expressed in , is calculated according to Equation (3) as follows: (3)
35、where is thermal conductivity, expressed in ; is taken from the calibration curve; is the height, expressed in metres, of the test specimen; is cross-sectional area, expressed in square metres, of the test specimen. 8P r e c i s i o n As specified in ASTM E691, the precision of this method is as fol
36、lows. a) The repeatability in is calculated by the following equation: b) The reproducibility in is calculated by the following equation: hd 0,1 C U A/h U dQ/dt 1/ W/(Km) = dQ dt 1 h A W/(Km) dQ dt 1 h A r W/(mK) r= 0,083 0,72 R W/(mK) R= 0,124+ 1,097ISO 12987:2004(E) ISO 2004 All rights reserved 5
37、9 Test report The test report shall include the following information: a) all details necessary for the complete identification of the sample; b) a reference to this International Standard (ISO 12987:2004); c) the measuring temperatures; d) the results and the method used; e) details of any unusual
38、features noted during the determination; f) details of any operation not included in this International Standard or in the International Standards to which reference is made, as well as any operation regarded as optional.ISO 12987:2004(E) 6 ISO 2004 All rights reserved Bibliography 1 ISO 3611, Micro
39、meter callipers for external measurement 2 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method 3 ISO 6906, Vernier callipers reading to 0,02 mm 4 ISO 800
40、7-1, Carbonaceous materials used in the production of aluminium Sampling plans and sampling from individual units Part 1: Cathode blocks 5 ISO 8007-2, Carbonaceous materials used in the production of aluminium Sampling plans and sampling from individual units Part 2: Prebaked anodes 6 ASTM E691, Sta
41、ndard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 7 DIN 51908, Testing of carbonaceous materials Determination of thermal conductivity at room temperature by means of a comparative method Solids. 7 ISO 12987:2004(E) ICS 71.100.10 Price based on 6 pages ISO 2004 All rights reserved
