1、Designation: C 767 93 (Reapproved 2004)Standard Test Method forThermal Conductivity of Carbon Refractories1This standard is issued under the fixed designation C 767; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 supplements Test Method C 201, andshall be used in conjunction with that procedure to determinethe therma
3、l conductivity of carbon or carbon-bearing refracto-ries. This test method is designed for refractories having aconductivity factor of not more than 200 Btuin./hft2F (28.8W/mK).1.2 The values stated in inch-pound units are to be regardedas the standard.1.3 This standard does not purport to address a
4、ll 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 155 Classificatio
5、n of Insulating FirebrickC 201 Test Method for Thermal Conductivity of Refracto-riesE 220 Method for Calibration of Thermocouples by Com-parison Techniques3. Significance and Use3.1 The thermal conductivity of carbon refractories is aproperty required for selecting their thermal transmissioncharacte
6、ristics. Users select carbon refractories to providespecified conditions of heat loss and cold face temperature,without exceeding the temperature limitation of the carbonrefractory. This test method establishes placement of thermo-couples and positioning of test specimens in the calorimeter.3.2 This
7、 procedure must be used with Test Method C 201and requires a large thermal gradient and steady state condi-tions. The results are based upon a mean temperature.3.3 The data from this test method is suitable for specifica-tion acceptance, estimating heat loss and surface temperature,and the design of
8、 multi-layer refractory construction.3.4 The use of these data requires consideration of the actualapplication environment and conditions.4. Apparatus4.1 The apparatus shall be in accordance with Test MethodC 201 with the addition of thermocouples, back-up insulation,and refractory fiber paper as de
9、scribed in Section 5 of this testmethod.5. Test Specimen and Preparation5.1 Select the test specimen and prepare in accordance withTest Method C 201.5.2 ThermocouplesEmbed calibrated thermocouples3inthe test specimen at two points for measuring temperature.Thermocouples4sheathed with material having
10、 low reactivitywith carbon must be used. Use the top thermocouple for onetest only.5.3 Installation of Thermocouples Place the hot junctionof the thermocouples in the center of each 9 by 412-in. (228 by114-mm) face and just below the surface of the test specimen.Cut grooves to receive the wire in ea
11、ch 9 by 412-in. face of thebrick to a depth necessary to embed the thermocouple justbeneath the surface by means of an abrasive wheel. The layoutfor the grooves allows all of the cold-junction ends of the wiresto extend from one end of the brick. Cut a groove in the centerof each 9 by 412-in. face a
12、long the 9-in. dimension and end14in. (6 mm) beyond the center. Before cementing5the thermo-couples in place, take measurements to obtain, within 60.01in. (60.3 mm), the eventual distance between the center linesof the thermocouple junctions. Do this by measuring the212-in. (64-mm) dimension of the
13、brick at the location for thehot junctions and deducting the distance between the centerline of each junction in its embedded position and the surfaceof the brick.1This test method is under the jurisdiction of ASTM Committee C08 onRefractories and is the direct responsibility of Subcommittee C08.02
14、on ThermalProperties.Current edition approved Sept. 1, 2004. Published October 2004. Originallyapproved in 1973. Last previous edition approved in 1998 as C 767 93 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
15、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Method E 220 specifies calibration procedures for thermocouples.4Claud S. Gordon Co., 5710 Kenosha St., Richmond, IL 60071, 1/16 -in.(2-mm) sheathed Xactpak thermocouple, Cat. No. 401-2104
16、or equivalent.5Alundum Cement RA 562 supplied by the Norton Co., One New Bond St.,Worcester, MA 01606, is satisfactory for this purpose.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.4 Cover the calorimeter and inner and outer gua
17、rds with a0.50-in. (12.7-mm) thick layer of Group 20 insulating firebrick(see Classification C 155) for the purpose of obtaining a highermean temperature in the test sample than would result byplacing the sample directly over the calorimeter area. Cut andgrind the back-up insulation so as to provide
18、 surfaces that areplane and do not vary from parallel by more than 60.01 in.(0.3 mm). Grind the sides of the pieces that are to be placed incontact plane and at right angles to the horizontal faces. Makethe joints between the pieces tight without the use of anymortar.5.5 Place two strips of refracto
19、ry fiber paper 1312 by12 by0.02 in. (342 by 13 by 0.5 mm) along the 1312-in. dimensionof the inner guard at the outside edges. Place twelve strips ofrefractory fiber paper 2 by12 by 0.02 in. (51 by 13 by 0.5 mm)on the outer guards at intervals in the pattern shown in Fig. 1.These strips serve as spa
20、ces to prevent contact between theback-up insulation or the test material and the calorimeterassembly. Then place the back-up insulation on the calorimeterassembly so as to provide a level and plane surface. Placeadditional strips of refractory fiber paper of the same dimen-sions in the same pattern
21、 upon the back-up insulation. Thesestrips serve as spacers to prevent contact between the carbonbrick and the back-up insulation. Place the test specimencentrally over the center of the calorimeter section on its 9 by412-in. (228 by 114-mm) face, place the guard brick at the sidesof the test specime
22、n so as to cover completely the calorimeterand inner guard area, and place the soap brick along the edgesof the three brick so as to cover completely the calorimeterassembly. Fill the small space between the furnace walls andthe test brick assembly with granulated insulating firebrick.5.6 Place the
23、silicon carbide slab over the 9 by 1312-in. (228by 342-mm) area of the three 9-in. (228-mm) brick specimen,and space it 1 in. nominal above the specimen by placing undereach corner of the slab rectangular pieces of Group 28insulating firebrick (see Classification C 155) cut to measure38-in. (10-mm)
24、square and 1-in. nominal length.6. Conditions of Test6.1 Make a special effort to seal the furnace tightly so thatthe atmosphere can be maintained nonoxidizing through intro-duction of argon under slight positive pressure as measured bya draft gage. In addition, place several pieces of carbonrefract
25、ory around the edges of the furnace on top of the outerguard brick to react with any oxygen that may enter the furnacechamber. The argon should not impinge on the test samples,but should impinge on these additional pieces of carbon.Maintain the atmosphere void of oxygen throughout the test.7. Proced
26、ure7.1 Place the heating chamber in position, start waterflowing through the calorimeter assembly, and supply currentto the heating unit. Maintain the rate of water flow through thecalorimeter between 120 and 200 g/min. Determine the flow byweighing the quantity of water collected during a measuredt
27、ime period. The weight of water collected shall not be lessthan 200 g and shall be weighed to an accuracy of 60.5 g. Therate of flow shall be constant within 61 % during the testperiod.7.2 Allow the furnace to reach a condition of steady state ofheat flow at various mean temperatures successively in
28、creased.A steady state shall be that condition when the measured flowof heat into the calorimeter varies less than 2 % over a 2-hperiod, during which time the temperature difference betweenthe calorimeter and the inner guard has not been more than0.05F (0.03C), the hot face of the test specimen has
29、notvaried more than 5F (3C), and the temperature of the waterentering the calorimeter has not varied at a rate of more than1F (0.5C)/h (Note 1). Usually, 12 h or more are needed toobtain a balance with the apparatus after a definite change ismade in the hot-face temperature.NOTE 1Significant errors
30、will result if the tolerances specified areexceeded.7.3 After the steady state of heat flow has been reached,measure the temperature of the test specimen, the rate of waterflow through the calorimeter, and the temperature rise of thewater flowing through the calorimeter. Take at least four sets ofre
31、adings at approximately 30-min intervals during the 2-hholding period, and these shall be averaged for the final valuesfor that particular heating chamber temperature.NOTE 2From these data a preliminary thermal conductivity calcula-tion may be made, using estimated distances between thermocouplejunc
32、tions in the test specimen.7.4 At the conclusion of the test, examine the specimens forchanges which may have taken place as a result of the heattreatment. Then remove the thermocouple wires, cut the brickin half through the 412 by 212-in. (114 by 64-mm) dimension,and examine for voids and cracks.8.
33、 Calculation8.1 Make the record of test data, the calculations, and thereport in accordance with Test Method C 201.9. Precision and Bias9.1 Refer to Test Method C 201 for a statement of precisionand bias.FIG. 1 Arrangement of Refractory-Fiber Paper Strips inCalorimeter AssemblageC 767 93 (2004)210.
34、Keywords10.1 calorimeter; carbon refractories; refractories; thermalconductivityASTM 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 val
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37、 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 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), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 767 93 (2004)3
