1、Designation: C1113/C1113M 09 (Reapproved 2013)Standard Test Method forThermal Conductivity of Refractories by Hot Wire (PlatinumResistance Thermometer Technique)1This standard is issued under the fixed designation C1113/C1113M; the number immediately following the designation indicates the yearof or
2、iginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of thermalconductiv
3、ity of non-carbonacious, dielectric refractories.1.2 Applicable refractories include refractory brick, refrac-tory castables, plastic refractories, ramming mixes, powderedmaterials, granular materials, and refractory fibers.1.3 Thermal conductivity k-values can be determined fromroom temperature to
4、1500C 2732F, or the maximumservice limit of the refractory, or to the temperature at whichthe refractory is no longer dielectric.1.4 This test method is applicable to refractories withk-values less than 15 W/mK 100 Btuin./hft2F.1.5 In general it is difficult to make accurate measurementsof anisotrop
5、ic materials, particularly those containing fibers,and the use of this test method for such materials should beagreed between the parties concerned.1.6 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be
6、exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.7 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the us
7、er of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C134 Test Methods for Size, Dimensional Measurements,and Bulk Density of Refractory Brick and InsulatingFirebrickC2
8、01 Test Method for Thermal Conductivity of RefractoriesC865 Practice for Firing Refractory Concrete SpecimensE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:DIS*8894-2 Refractory Materials - Determination of Ther-mal Conductivity up to
9、 1250C of Dense and InsulatingRefractory Products According to the Hot Wire ParallelMethod33. Terminology3.1 Symbols:3.1.1 RThot wire resistance at any temperature, ohms.3.1.2 R0hot wire resistance at 0C 32F (from an icebath), ohms.3.1.3 Lhot wire length, cm.3.1.4 Tsample test temperature, C.3.1.5 V
10、average voltage drop across hot wire, volts.3.1.6 Vsaverage voltage drop across standard resistor,volts.3.1.7 Rsaverage resistance of standard resistor, ohms.3.1.8 Iaverage current through hot wire (Vs/Rs), amperes.3.1.9 Qaverage power input to hot wire (I*V*100/L)during test, watts/m.3.1.10 ttime,
11、min.3.1.11 Bslope of linear region in RTvs. ln(t) plot.3.1.12 kthermal conductivity, W/mK.3.1.13 a, b, ccoefficients of a second degree polynomialequation relating hot wire resistance and temperature.3.1.14 V, I, and Q are preferably measured in the linearregion of the RTversus ln(t) plot for maximu
12、m data accuracy.1This test method is under the jurisdiction of ASTM Committee C08 onRefractories and is the direct responsibility of Subcommittee C08.02 on ThermalProperties.Current edition approved Sept. 1, 2013. Published September 2013. Originallyapproved in 1990. Last previous edition approved i
13、n 2009 as C1113/C1113M09.DOI: 10.1520/C1113_C1113M-09R13.2For 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.3Ava
14、ilable from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 A constant electrical current is a
15、pplied to a pure plati-num wire placed between two brick. The rate at which the wireheats is dependent upon how rapidly heat flows from the wireinto the constant temperature mass of the refractory brick. Therate of temperature increase of the platinum wire is accuratelydetermined by measuring its in
16、crease in resistance in the sameway a platinum resistance thermometer is used. A Fourierequation is used to calculate the k-value based on the rate oftemperature increase of the wire and power input.45. Significance and Use5.1 The k-values determined at one or more temperaturescan be used for rankin
17、g products in relative order of theirthermal conductivities.5.2 Estimates of heat flow, interface temperatures, and coldface temperatures of single, and multi-component linings canbe calculated using k-values obtained over a wide temperaturerange.5.3 The k-values determined are “at temperature” meas
18、ure-ments rather than “mean temperature” measurements. Thus, awide range of temperatures can be measured, and the resultsare not averaged over the large thermal gradient inherent inwater-cooled calorimeters.5.4 The k-values measured are the combination of thek-values for the width and thickness of t
19、he sample, as the heatflow from the hot wire is in both of those directions. Thewater-cooled calorimeter measures k-value in one direction,through the sample thickness.5.5 The test method used should be specified when report-ing k-values, as the results obtained may vary with the type oftest method
20、that is used. Data obtained by the hot wire methodare typically 10 to 30 % higher than data obtained by the watercalorimeter method given in Test Method C201.6. Apparatus6.1 A block diagram of a suggested test apparatus is shownin Fig. 1. Details of the equipment are as follows:6.1.1 Furnace, with a
21、 heating chamber capable of support-ing two 228-mm 9-in. straight brick. The furnace temperaturemay be controlled with a set point controller adjusted manuallybetween test temperatures, with a programmable controller, orwith the computer. If a programmable controller is used, andthe hot wire power i
22、s applied by computer, the furnacetemperature program must be synchronized with the computerprogram used to collect the test data. The furnace temperatureshould be accurate to 6 5C 9F and controlled to within a 61C 1.8F precision such that the temperature variation withtime is minimized. Temperature
23、 stability measurements are notrequired by this test method because small temperature varia-tions with time are difficult to measure and dependent onthermocouple placement (in air, a protection tube, or in thesample). However, if sample temperature measurements areaveraged during a 30 minute period
24、after furnace equilibration(prior to a hot wire test), the maximum-minimum differenceshould preferably be less than 1C 1.8F. In addition, if alinear regression analysis is done on the average temperaturevs. time data, the rate of temperature change should preferablybe less than 0.05C 0.09F/min. Four
25、 holes with aluminaprotection tubes shall be provided in the kiln wall for theplatinum voltage and current leads. These holes should bewidely spaced to minimize electrical conductivity at elevatedtemperatures.6.1.2 Thermocouple, to measure sample temperature.6.1.3 Programmable Power Supply, capable
26、of constantcurrent control in the range from 0 to 10 A (0 to 50 V). Duringa 10-min test period, stability should be 6 0.002 A. Size thepower supply according to the anticipated wire harnessesdiameter and type of materials to be tested. A high (510 A)ampere supply is suggested for large diameter wire
27、 and/ortesting of high conductivity materials. However, lower amperesupplies will giver better current control for low currents usedfor low conductivity materials or with a smaller diameter wireharness.6.1.4 Shunt, with a resistance of 0.1 rated at 15 A.6.1.5 Programmable Scanner, capable of directi
28、ng severaldifferent voltage inputs to the digital voltmeter. It is also usedto activate a relay to turn on and off the test circuit.6.1.6 Relay, with a current rating of 25 A at 24 V.6.1.7 Programmable Digital Voltmeter, with auto ranging,auto calibration, and 612 digit resolution.6.1.8 Computer, ca
29、pable of controlling the operation of thepower supply, scanner, and digital voltmeter. It must also beable to collect and analyze the test results. Commerciallyavailable data acquisition (with an IEEE device and sequentialfile numbering capability) and analysis (spreadsheet withmacro capability) sof
30、tware is acceptable; custom software isnot necessary.6.1.9 Printer/Plotter, capable of documenting the raw dataand various calculated values. The plotter function is used toplot the resistance versus ln (time) relationship. This is used tovisually determine if a linear relationship was obtained and
31、thelocation of the linear region.6.2 Reusable Test Harness, consisting of a straight section atleast 30-cm 11.8-in. long with two perpendicular voltage4Morrow, G. D., “Improved Hot Wire Thermal Conductivity Technique”, Bull.Amer. Ceram. Soc.,58 (7), 1979, pp. 68790.FIG. 1 Diagram of ApparatusC1113/C
32、1113M 09 (2013)2leads about 15-cm 5.9-in. apart near the center per Fig. 2.Toavoid thermocouple effect voltage errors, use pure platinumwire for the test harness, and for the entire length of voltageleads. Platinum alloy wire may be used only for current leadsfrom outside the furnace to the test har
33、ness section itself. Theplatinum voltage lead wires may be taken to an insulatedterminal box on the side of the furnace for connection to lowertemperature lead wires, or run all the way back to the digitalvoltmeter terminals. The main part of the harness wire shall bebetween 0.330 and 0.508-mm 0.013
34、 and 0.020-in. diameter.The voltage leads may be the same size as the main harnesswire, although it is recommended that they be 0.330-mm0.013-in. or smaller such that their area is less than half thatof the main wire. The current leads up to the main harness shallbe at least the same size as the mai
35、n harness wire. The mainharness may be fabricated by butt welding voltage leads to asolid main wire using a micro torch or arc percussion welder,or by arc welding the wires into a bead. If beads are made byarc welding, keep the bead size as small as possible, andcarefully straighten out the bead to
36、form a tee joint with thevoltage lead perpendicular to the main wire.7. Sampling and Specimen Preparation7.1 The test specimens consist of two 228-mm 9-in.straight brick or equivalent. Select these specimens for unifor-mity of structure and bulk density. Bulk density should bedetermined in accordanc
37、e with Test Method C134.7.2 The hot wire harness is positioned near the center of thetwo brick shaped specimens and in intimate contact with botheither by using samples with a step diamond ground into themating surface, by forming the sample around the harness, orby deformation of soft samples. See
38、Fig. 2 for a schematic ofhow the steps provide intimate lateral contact with both halvesof the sample assembly.7.2.1 Refractory BrickThe steps cut in the brick shall havea maximum depth of 0.8-mm 0.032-in., although lesserdepths can be used for wires smaller than the 0.508-mm0.020-in. maximum wire s
39、ize. To insure that samples do notrock, the average depth of both steps shall be within 0.1-mm0.004-in. of each other. In addition, the mating surfaces shallbe flat to less than 0.1-mm 0.004-in. as determined by thefollowing procedure. After the steps are ground, the bricksshall be placed together w
40、ith the steps touching each other tocheck for any noticable rock or movement between the twobricks; no visible movement is acceptable. Rock is most oftencaused by the use of a grinding wheel which has a high spot inthe center, causing a smaller step depth close to the step thanacross the rest of the
41、 mating surface. Dressing the wheel so thatit is flat or that the side which forms the step edge is high willnormally provide acceptable results. After the step height andmating surfaces are acceptable, voltage lead grooves shall becut across the high part of the step in one of the samples. Toaccomm
42、odate the weld beads at the junctions of the main wireand voltage leads, it is permissible to chip out small cavities inthe brick at these locations using a hammer and center punch.7.2.2 Refractory CastablesRefractory castables speci-mens can be cut into brick shapes and prepared as in 7.2.1 ora spe
43、cial castable mold with the 0.8-mm 0.032 in. step can beused to form the brick shapes. Two thin grooves must be cut forthe perpendicular voltage leads in one of the brick. The hotwire harness can also be cast in place for a single usage.7.2.3 Plastic Refractories and Ramming MixesImmediately after f
44、orming, press the hot wire harness betweentwo 228-mm 9-in. straight bricks. Pressure should be appliedduring drying to keep the brick in very close contact.7.2.4 Low-Strength MaterialsUse a sharp knife to scribegrooves into one of the brick into which the hot wire harnesswill be pressed.7.2.5 Compre
45、ssible Refractory Fiber BlanketsFabricate aweighted cover to compress and hold the samples to the desiredthickness (and bulk density) during testing. A cover and sidespacers are required.7.2.6 Powdered or Granular MaterialsA refractory con-tainer must be fabricated to contain powdered or granularmat
46、erials. The container may be of two parts each the size ofa 228-mm 9-in straight brick. The lower part will have foursides and a bottom. The upper part will have four sides only.Alternatively, a container of one part only may be used. Theone-part container will have the volume of two 228-mm 9-inbric
47、k. Record the weight and interior volume for use incalculating the apparent bulk density of the test material.8. Calibration8.1 Depending on the data analysis calculation methodused, it may be necessary to determine the resistance of eachtest harness at 0C 32F (Ro). This can be done experimen-tally
48、by placing the harness in a plastic tray with a slurry ofcrushed ice, and measuring the resistance using the same4-wire method which is used for elevated temperature resis-tance measurements. An alternate method is to measure theFIG. 2 Hot Wire Sample SetupC1113/C1113M 09 (2013)3resistance of the ha
49、rness at room temperature and calculate anRovalue from RT/Ro=(a+b*T+c*T2) where the equation coef-ficients are obtained from prior tests of the wire lot. Wireharness calibration at 0C 32F is not required if the wireresistance vs. temperature measurement method is used.9. Setup Procedure9.1 Measure the hot wire length, L, to the nearest 0.025-cm0.01-in. This distance is measured between the voltage leads.9.2 Refractory BrickPosition the hot wire harness on thegrooved brick. Place the
