1、Designation: C 1113 99 (Reapproved 2004)Standard Test Method forThermal Conductivity of Refractories by Hot Wire (PlatinumResistance Thermometer Technique)1This standard is issued under the fixed designation C 1113; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last 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 covers the determination of thermalconductivity of non-
3、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 1500C (2732
4、F), 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 anisotropic mate
5、rials, particularly those containing fibers,and the use of this test method for such materials should beagreed between the parties concerned.1.6 The values stated in SI units are to be regarded asstandard.1.7 This standard does not purport to address the safetyconcerns, if any, associated with its u
6、se. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 134 Test Methods for Size and Bulk Density of Refrac-tory Brick and Insulati
7、ng FirebrickC 201 Test Methods for Thermal Conductivity of Refracto-riesC 865 Practice for Firing Refractory Concrete SpecimensE 691 Practice for Conducting an Interlaboratory Test Pro-gram to Determine the Precision of Test Methods2.2 ISO Standard:DIS*8894-2 Refractory Materials - Determination of
8、Ther-mal Conductivity up to 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 Tsampl
9、e test temperature, C.3.1.5 Vaverage 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
10、 test, watts/m.3.1.10 ttime, 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
11、RTversus ln(t) plot for maximum data accuracy.4. Summary of Test Method4.1 A constant electrical current is applied 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 refra
12、ctory brick. Therate of temperature increase of the platinum wire is accuratelydetermined by measuring its increase in resistance in the sameway a platinum resistance thermometer is used. A Fourier1This test method is under the jurisdiction of ASTM Committee C08 onRefractories and is the direct resp
13、onsibility of Subcommittee C08.02 on Thermaland Thermochemical Properties.Current edition approved Sept. 1, 2004. Published October 2004. Originallyapproved in 1990. Last previous edition approved in 1999 as C 111399.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AST
14、M Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Har
15、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.equation 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 ranking products in re
16、lative 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” measure-ments rather
17、 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 the sample, as th
18、e 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 that is used. Da
19、ta obtained by the hot wire methodare typically 10 to 30 % higher than data obtained by the watercalorimeter method given in Test Method C 201.6. 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 heating chambe
20、r 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 is applied by
21、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 stabilit
22、y 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 after fur
23、nace 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 hole
24、s 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 of co
25、nstantcurrent 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 and/
26、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 V rated at 15 A.6.1.5 Programmable Scanner, capable of directing
27、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, capab
28、le 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) softwa
29、re 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 the
30、location of the linear region.6.2 Reusable Test Harness, consisting of a straight section atleast 30-cm (11.8-in.) long with two perpendicular voltageleads 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,
31、and for the entire length of voltageleads. Platinum alloy wire may be used only for current leadsfrom outside the furnace to the test harness section itself. Theplatinum voltage lead wires may be taken to an insulatedterminal box on the side of the furnace for connection to lowertemperature lead wir
32、es, 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 and 0.020-in.) diameter.4Morrow, G.D., “Improved Hot Wire Thermal Conductivity Technique”, Bull.Amer. Ceram. Soc., 58(7), 1979, pp. 68790.FIG. 1 Diagram of Appar
33、atusC 1113 99 (2004)2The voltage leads may be the same size as the main harnesswire, although it is recommended that they be 0.330-mm(0.013-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 main
34、 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 f
35、orm 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 accordan
36、ce with Test Method C 134.7.2 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. Se
37、e 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 shallhave a maximum depth of 0.8-mm (0.032-in.), although lesserdepths can be used for wires smaller than the 0.508-mm(0.020-in.) maximum
38、wire size. To insure that samples do notrock, the average depth of both steps shall be within 0.1-mm(0.004-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
39、together with 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 r
40、est of the 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
41、. Toaccommodate 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
42、.1 ora special 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 MixesImmedia
43、tely after forming, 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 presse
44、d.7.2.5 Compressible 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
45、or granularmaterials. 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
46、 228-mm (9-in)brick. 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 d
47、one experimen-tally 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 theresistance of the harness at room temperature and c
48、alculate 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
49、 nearest 0.025-cm(0.01-in.). This distance is measured between the voltage leads.FIG. 2 Hot Wire Sample SetupC 1113 99 (2004)39.2 Refractory BrickPosition the hot wire harness on thegrooved brick. Place the other brick on top and slide themtogether to lock the wire into very close contact with bothbricks.9.3 Low-Strength MaterialsPress the hot wire harnessinto the scribed grooves.9.4 Compressible Refractory Fiber BlanketsPosition thehot wire harness between the fiber samples. Several layers maybe necessary for thin samples.9.5 Powder
