ASTM C1113/C1113M-09(2013)
(Test Method)Standard Test Method for Thermal Conductivity of Refractories by Hot Wire (Platinum Resistance Thermometer Technique)
Standard Test Method for Thermal Conductivity of Refractories by Hot Wire (Platinum Resistance Thermometer Technique)
SIGNIFICANCE AND USE
5.1 The k-values determined at one or more temperatures can be used for ranking products in relative order of their thermal conductivities.
5.2 Estimates of heat flow, interface temperatures, and cold face temperatures of single, and multi-component linings can be calculated using k-values obtained over a wide temperature range.
5.3 The k-values determined are “at temperature” measurements rather than “mean temperature” measurements. Thus, a wide range of temperatures can be measured, and the results are not averaged over the large thermal gradient inherent in water-cooled calorimeters.
5.4 The k-values measured are the combination of the k-values for the width and thickness of the sample, as the heat flow from the hot wire is in both of those directions. The water-cooled calorimeter measures k-value in one direction, through the sample thickness.
5.5 The test method used should be specified when reporting k-values, as the results obtained may vary with the type of test method that is used. Data obtained by the hot wire method are typically 10 to 30 % higher than data obtained by the water calorimeter method given in Test Method C201.
SCOPE
1.1 This test method covers the determination of thermal conductivity of non-carbonacious, dielectric refractories.
1.2 Applicable refractories include refractory brick, refractory castables, plastic refractories, ramming mixes, powdered materials, granular materials, and refractory fibers.
1.3 Thermal conductivity k-values can be determined from room temperature to 1500°C [2732°F], or the maximum service limit of the refractory, or to the temperature at which the refractory is no longer dielectric.
1.4 This test method is applicable to refractories with k-values less than 15 W/m·K [100 Btu·in./h·ft 2·°F].
1.5 In general it is difficult to make accurate measurements of anisotropic materials, particularly those containing fibers, and the use of this test method for such materials should be agreed between the parties concerned.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be 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 safety concerns, if any, associated with it's use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: C1113/C1113M − 09 (Reapproved 2013)
Standard Test Method for
Thermal Conductivity of Refractories by Hot Wire (Platinum
Resistance Thermometer Technique)
ThisstandardisissuedunderthefixeddesignationC1113/C1113M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope C134Test Methods for Size, Dimensional Measurements,
and Bulk Density of Refractory Brick and Insulating
1.1 This test method covers the determination of thermal
Firebrick
conductivity of non-carbonacious, dielectric refractories.
C201Test Method forThermal Conductivity of Refractories
1.2 Applicable refractories include refractory brick, refrac-
C865Practice for Firing Refractory Concrete Specimens
tory castables, plastic refractories, ramming mixes, powdered
E691Practice for Conducting an Interlaboratory Study to
materials, granular materials, and refractory fibers.
Determine the Precision of a Test Method
1.3 Thermal conductivity k-values can be determined from
2.2 ISO Standard:
room temperature to 1500°C [2732°F], or the maximum
DIS*8894-2Refractory Materials - Determination of Ther-
service limit of the refractory, or to the temperature at which
mal Conductivity up to 1250°C of Dense and Insulating
the refractory is no longer dielectric.
Refractory Products According to the Hot Wire Parallel
Method
1.4 This test method is applicable to refractories with
k-values less than 15 W/m·K [100 Btu·in./h·ft ·°F].
3. Terminology
1.5 In general it is difficult to make accurate measurements
of anisotropic materials, particularly those containing fibers, 3.1 Symbols:
and the use of this test method for such materials should be 3.1.1 R —hot wire resistance at any temperature, ohms.
T
agreed between the parties concerned.
3.1.2 R —hot wire resistance at 0°C [32°F] (from an ice
bath), ohms.
1.6 Units—The values stated in either SI units or inch-
pound units are to be regarded separately as standard. The
3.1.3 L—hot wire length, cm.
values stated in each system may not be exact equivalents;
3.1.4 T—sample test temperature, °C.
therefore,eachsystemshallbeusedindependentlyoftheother.
3.1.5 V—average voltage drop across hot wire, volts.
Combining values from the two systems may result in non-
conformance with the standard.
3.1.6 V —average voltage drop across standard resistor,
s
volts.
1.7 This standard does not purport to address the safety
concerns, if any, associated with it’s use. It is the responsibility
3.1.7 R —average resistance of standard resistor, ohms.
s
of the user of this standard to establish appropriate safety and
3.1.8 I—average current through hot wire (V /R ), amperes.
s s
health practices and determine the applicability of regulatory
3.1.9 Q—average power input to hot wire (I*V*100/L)
limitations prior to use.
during test, watts/m.
2. Referenced Documents
3.1.10 t—time, min.
2.1 ASTM Standards:
3.1.11 B—slope of linear region in R vs. ln(t) plot.
T
3.1.12 k—thermal conductivity, W/m·K.
3.1.13 a, b, c—coefficients of a second degree polynomial
This test method is under the jurisdiction of ASTM Committee C08 on
equation relating hot wire resistance and temperature.
Refractories and is the direct responsibility of Subcommittee C08.02 on Thermal
Properties.
3.1.14 V, I, and Q are preferably measured in the linear
Current edition approved Sept. 1, 2013. Published September 2013. Originally
region of the R versus ln(t) plot for maximum data accuracy.
approved in 1990. Last previous edition approved in 2009 as C1113/C1113M–09. T
DOI: 10.1520/C1113_C1113M-09R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 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 States
C1113/C1113M − 09 (2013)
4. Summary of Test Method
4.1 A constant electrical current is applied to a pure plati-
numwireplacedbetweentwobrick.Therateatwhichthewire
heats is dependent upon how rapidly heat flows from the wire
into the constant temperature mass of the refractory brick. The
rate of temperature increase of the platinum wire is accurately
determined by measuring its increase in resistance in the same
way a platinum resistance thermometer is used. A Fourier
equation is used to calculate the k-value based on the rate of
temperature increase of the wire and power input.
5. Significance and Use
5.1 The k-values determined at one or more temperatures
can be used for ranking products in relative order of their
thermal conductivities. FIG. 1 Diagram of Apparatus
5.2 Estimates of heat flow, interface temperatures, and cold
averaged during a 30 minute period after furnace equilibration
face temperatures of single, and multi-component linings can
(prior to a hot wire test), the maximum-minimum difference
be calculated using k-values obtained over a wide temperature
should preferably be less than 1°C [1.8°F]. In addition, if a
range.
linear regression analysis is done on the average temperature
5.3 The k-values determined are “at temperature” measure-
vs. time data, the rate of temperature change should preferably
ments rather than “mean temperature” measurements. Thus, a
be less than 0.05°C [0.09°F]/min. Four holes with alumina
wide range of temperatures can be measured, and the results
protection tubes shall be provided in the kiln wall for the
are not averaged over the large thermal gradient inherent in
platinum voltage and current leads. These holes should be
water-cooled calorimeters.
widely spaced to minimize electrical conductivity at elevated
temperatures.
5.4 The k-values measured are the combination of the
6.1.2 Thermocouple, to measure sample temperature.
k-values for the width and thickness of the sample, as the heat
6.1.3 Programmable Power Supply, capable of constant
flow from the hot wire is in both of those directions. The
current control in the range from 0 to 10A(0 to 50V). During
water-cooled calorimeter measures k-value in one direction,
a 10-min test period, stability should be 6 0.002 A. Size the
through the sample thickness.
power supply according to the anticipated wire harnesses
5.5 The test method used should be specified when report-
diameter and type of materials to be tested. A high (5–10 A)
ing k-values, as the results obtained may vary with the type of
ampere supply is suggested for large diameter wire and/or
test method that is used. Data obtained by the hot wire method
testing of high conductivity materials. However, lower ampere
aretypically10to30%higherthandataobtainedbythewater
supplies will giver better current control for low currents used
calorimeter method given in Test Method C201.
for low conductivity materials or with a smaller diameter wire
harness.
6. Apparatus
6.1.4 Shunt, with a resistance of 0.1 Ω rated at 15 A.
6.1 Ablock diagram of a suggested test apparatus is shown
6.1.5 Programmable Scanner, capable of directing several
in Fig. 1. Details of the equipment are as follows:
different voltage inputs to the digital voltmeter. It is also used
6.1.1 Furnace, with a heating chamber capable of support-
to activate a relay to turn on and off the test circuit.
ingtwo228-mm[9-in.]straightbrick.Thefurnacetemperature
6.1.6 Relay, with a current rating of 25 A at 24 V.
maybecontrolledwithasetpointcontrolleradjustedmanually
6.1.7 Programmable Digital Voltmeter, with auto ranging,
between test temperatures, with a programmable controller, or
auto calibration, and 6 ⁄2 digit resolution.
with the computer. If a programmable controller is used, and
6.1.8 Computer, capable of controlling the operation of the
the hot wire power is applied by computer, the furnace
power supply, scanner, and digital voltmeter. It must also be
temperature program must be synchronized with the computer
able to collect and analyze the test results. Commercially
program used to collect the test data. The furnace temperature
available data acquisition (with an IEEE device and sequential
shouldbeaccurateto 65°C[9°F]andcontrolledtowithina 6
file numbering capability) and analysis (spreadsheet with
1°C [1.8°F] precision such that the temperature variation with
macro capability) software is acceptable; custom software is
timeisminimized.Temperaturestabilitymeasurementsarenot
not necessary.
required by this test method because small temperature varia-
6.1.9 Printer/Plotter, capable of documenting the raw data
tions with time are difficult to measure and dependent on
and various calculated values. The plotter function is used to
thermocouple placement (in air, a protection tube, or in the
plot the resistance versus ln (time) relationship.This is used to
sample). However, if sample temperature measurements are
visually determine if a linear relationship was obtained and the
location of the linear region.
6.2 Reusable Test Harness,consistingofastraightsectionat
Morrow, G. D., “Improved Hot Wire Thermal Conductivity Technique,”Bull.
Amer. Ceram. Soc., 58(7), 1979, pp.687–90. least 30-cm [11.8-in.] long with two perpendicular voltage
C1113/C1113M − 09 (2013)
leads about 15-cm [5.9-in.] apart near the center per Fig. 2.To by deformation of soft samples. See Fig. 2 for a schematic of
avoid thermocouple effect voltage errors, use pure platinum how the steps provide intimate lateral contact with both halves
wire for the test harness, and for the entire length of voltage of the sample assembly.
leads. Platinum alloy wire may be used only for current leads 7.2.1 Refractory Brick—Thestepscutinthebrickshallhave
from outside the furnace to the test harness section itself. The a maximum depth of 0.8-mm [0.032-in.], although lesser
platinum voltage lead wires may be taken to an insulated depths can be used for wires smaller than the 0.508-mm
terminal box on the side of the furnace for connection to lower [0.020-in.] maximum wire size. To insure that samples do not
temperature lead wires, or run all the way back to the digital rock, the average depth of both steps shall be within 0.1-mm
voltmeter terminals.The main part of the harness wire shall be [0.004-in.] of each other. In addition, the mating surfaces shall
between 0.330 and 0.508-mm [0.013 and 0.020-in.] diameter. be flat to less than 0.1-mm [0.004-in.] as determined by the
The voltage leads may be the same size as the main harness following procedure. After the steps are ground, the bricks
wire, although it is recommended that they be 0.330-mm shall be placed together with the steps touching each other to
[0.013-in.] or smaller such that their area is less than half that check for any noticable rock or movement between the two
ofthemainwire.Thecurrentleadsuptothemainharnessshall bricks; no visible movement is acceptable. Rock is most often
be at least the same size as the main harness wire. The main caused by the use of a grinding wheel which has a high spot in
harness may be fabricated by butt welding voltage leads to a the center, causing a smaller step depth close to the step than
solid main wire using a micro torch or arc percussion welder, acrosstherestofthematingsurface.Dressingthewheelsothat
or by arc welding the wires into a bead. If beads are made by it is flat or that the side which forms the step edge is high will
arc welding, keep the bead size as small as possible, and normally provide acceptable results. After the step height and
carefully straighten out the bead to form a tee joint with the mating surfaces are acceptable, voltage lead grooves shall be
voltage lead perpendicular to the main wire. cut across the high part of the step in one of the samples. To
accommodate the weld beads at the junctions of the main wire
7. Sampling and Specimen Preparation
and voltage leads, it is permissible to chip out small cavities in
the brick at these locations using a hammer and center punch.
7.1 The test specimens consist of two 228-mm [9-in.]
7.2.2 Refractory Castables—Refractory castables speci-
straight brick or equivalent. Select these specimens for unifor-
mens can be cut into brick shapes and prepared as in 7.2.1 or
mity of structure and bulk density. Bulk density should be
aspecialcastablemoldwiththe0.8-mm[0.032in.]stepcanbe
determined in accordance with Test Method C134.
usedtoformthebrickshapes.Twothingroovesmustbecutfor
7.2 The hot wire harness is positioned near the center of the
the perpendicular voltage leads in one of the brick. The hot
two brick shaped specimens and in intimate contact with both
wire harness can also be cast in place for a single usage.
either by using samples with a step diamond ground into the
7.2.3 Plastic Refractories and Ramming Mixes—
mating surface, by forming the sample around the harness, or
Immediately after forming, press the hot wire harness between
two 228-mm [9-in.] straight bricks. Pressure should be applied
during drying to keep the brick in very close contact.
7.2.4 Low-Strength Materials—Use a sharp knife to scribe
grooves into one of the brick into which the hot wire harness
will be pressed.
7.2.5 Compressible Refractory Fiber Blankets—Fabricate a
weightedcovertocompressandholdthesamplestothedesired
thickness (and bulk density) during testing. A cover and side
spacers are required.
7.2.6 Powdered or Granular Materials—A refractory con-
tainer must be fabricated to contain powdered or granular
materials. The container may be of two parts each the size of
a 228-mm [9-in] straight brick. The lower part will have four
sides and a bottom. The upper part will have four sides only.
Alternatively, a container of one part only may be used. The
one-part container will have the volume of two 228-mm [9-in]
brick. Record the weight and interior volume for use in
calculating the apparent bulk density of the test material.
8. Calibration
8.1 Depending on the data analysis calculation method
used, it may be necessary to determine the resistance of each
test harness at 0°C [32°F] (R ). This can be done experimen-
o
tally by placing the harness in a plastic tray with a slurry of
crushed ice, and measuring the resistance using the same
4-wire method which is used for elevated temperature resis-
FIG. 2 Hot Wire Sample Setup tance measurements. An alternate method is to measure the
C1113/C1113M − 09 (2013)
resistance of the harness at ro
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