ASTM C767 - 20

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Designation: C767 −20
Standard Test Method for
Thermal Conductivity of Carbon Refractories
1
This standard is issued under the ﬁxed designation C767; the number immediately following the designation indicates the year of
original 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. Scope
1.1 This test method supplements Test Method C201, and
shall be used in conjunction with that test method to determine
the thermal conductivity of carbon or carbon-bearing refracto-
ries. This test method is designed for refractories having a
conductivity factor of not more than 200 Btu·in./h·ft
2
·°F
(28.8 W ⁄m·K).
1.2 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered standard.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
C155 Classiﬁcation of Insulating Firebrick
C201 Test Method for Thermal Conductivity of Refractories
E220 Test Method for Calibration of Thermocouples By
Comparison Techniques
3. Signiﬁcance and Use
3.1 The thermal conductivity of carbon refractories is a
property required for selecting their thermal transmission
characteristics. Users select carbon refractories to provide
speciﬁed conditions of heat loss and cold-face temperature
without exceeding the temperature limitation of the carbon
refractory. This test method establishes placement of thermo-
couples and positioning of test specimens in the calorimeter.
3.2 This procedure must be used with Test Method C201
and 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 multi-layer refractory construction.
3.4 The use of these data requires consideration of the actual
application environment and conditions.
4. Apparatus
4.1 The apparatus shall consist of that described in Test
Method C201 with the addition of thermocouples, back-up
insulation, and refractory ﬁber paper as described in Section 5
of this test method.
5. Test Specimen and Preparation
5.1 Select the test specimen and prepare in accordance with
Test Method C201.
5.2 Thermocouples—Calibrated thermocouples
3
shall be
embedded in the test specimen at two points for measuring the
temperature. Thermocouples
4
sheathed with material having
low reactivity with carbon must be used. Use the top thermo-
couple for one test only.
5.3 Installation of Thermocouples—The hot junction of the
thermocouples shall be placed in the center of each 9 by 4
1
⁄
2
-in.
(228 by 114-mm) face and just below the surface of the test
specimen. Grooves to receive the wire shall be cut in each 9 by
4
1
⁄
2
-in. face of the brick to a depth necessary to embed the
thermocouple just beneath the surface by means of an abrasive
wheel. The layout for the grooves allows all of the cold-
junction ends of the wires to extend from one end of the brick.
Cut a groove in the center of each 9 by 4
1
⁄
2
-in. face along the
9-in. dimension and end
1
⁄
4
in. (6 mm) beyond the center.
1
This test method is under the jurisdiction of ASTM Committee C08 on
Refractories and is the direct responsibility of Subcommittee C08.02 on Thermal
Properties.
Current edition approved April 1, 2020. Published April 2020. Originally
approved in 1973. Last previous edition approved in 2013 as C767 – 93 (2013).
DOI: 10.1520/C0767-20.
2
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
the ASTM website.
3
Test Method E220 speciﬁes calibration procedures for thermocouples.
4
Claud S. Gordon Co., 5710 Kenosha St., Richmond, IL 60071,
1
⁄
16
-in. (2-mm)
sheathed Xactpak thermocouple, Cat. No. 401-2104 or equivalent.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Before cementing

the thermocouples in place, measurements

shall be taken to obtain, within 60.01 in. (60.3 mm), the

eventual distance between the center lines of the thermocouple

junctions. This shall be done by measuring the 2

⁄

-in. (64-mm)

dimension of the brick at the location for the hot junctions and

deducting the distance between the center line of each junction

in its embedded position and the surface of the brick.

5.4 The calorimeter and inner and outer guards shall be

covered with a 0.50-in. (12.7-mm) thick layer of Group 20

insulating ﬁrebrick (see Classiﬁcation C155) for the purpose of

obtaining a higher mean temperature in the test sample than

would result by placing the sample directly over the calorim-

eter area. The back-up insulation shall be cut and ground so as

to provide surfaces that are plane and do not vary from parallel

by more than 60.01 in. (0.3 mm). The sides of the pieces that

are to be placed in contact shall be ground plane and at right

angles to the horizontal faces. The joints between the pieces

shall be tight without the use of any mortar.

5.5 Two strips of refractory ﬁber paper 13

⁄

by 0.02

in. (342 by 13 by 0.5 mm) shall be placed along the 13

⁄

-in.

(343-mm) dimension of the inner guard at the outside edges.

Twelve strips of refractory ﬁber paper 2 by

⁄

by 0.02 in. (51

by 13 by 0.5 mm) shall be placed on the outer guards at

intervals in the pattern shown in Fig. 1. These strips serve as

spaces to prevent contact between the back-up insulation and

the calorimeter assembly. Then place the back-up insulation on

the calorimeter assembly so as to provide a level and plane

surface. Place additional strips of refractory ﬁber paper of the

same dimensions in the same pattern upon the back-up

insulation. These strips serve as spacers to prevent contact

between the carbon brick and the back-up insulation. The test

specimen shall be placed centrally over the center of the

calorimeter section on its 9 by 4

⁄

-in. (228 by 114-mm) face,

the guard brick placed at the sides of the test specimen so as to

completely cover the calorimeter and inner guard area, and the

soap brick placed along the edges of the three brick so as to

completely cover the calorimeter assembly. The small space

between the furnace walls and the test brick assembly shall be

ﬁlled with granulated insulating ﬁrebrick.

5.6 The silicon carbide slab shall be placed over the 9 by

⁄

-in. (228 by 342-mm) area of the three 9-in. (228-mm)

brick specimen, and it shall be spaced 1 in. (25.4 mm) above

the specimen by placing under each corner of the slab

rectangular pieces of Group 28 insulating ﬁrebrick (see Clas-

siﬁcation C155) cut to measure

⁄

in. (10 mm) square and 1 in.

(25.4 mm) in length.

6. Conditions of Test

6.1 A special effort to seal the furnace tightly is to be made

in order to maintain a nonoxidizing atmosphere by means of an

introduction of an argon ﬂow. In addition, several pieces of

carbon refractory placed around the edges of the furnace on top

of the outer guard brick will react with any oxygen that may

enter the furnace chamber. The argon should not impinge on

these additional pieces of carbon and should not impinge on the

test specimen. Maintain the atmosphere void of oxygen

throughout the test.

7. Procedure

7.1 Place the heating chamber in position, start water

ﬂowing through the calorimeter assembly, and supply current

to the heating unit. Maintain the rate of water ﬂow through the

calorimeter between 120 and 200 g/min, and determine by

weighing the quantity of water collected during a measured

time period. The mass of water collected shall not be less than

200 g and shall be weighed to an accuracy of 60.5 g. The rate

of ﬂow shall be constant within 61 % during the test period.

7.2 Allow the furnace to reach a condition of steady state of

heat ﬂow at various mean temperatures successively increased.

A steady state shall be that condition when the measured ﬂow

of heat into the calorimeter varies less than 2 % over a 2-h

period, during which time the temperature difference between

the calorimeter and the inner guard has not been more than

0.05 °F (0.03 °C), the hot face of the test specimen has not

varied more than 5 °F (3 °C), and the temperature of the water

entering the calorimeter has not varied at a rate of more than

1 °F (0.5 °C) ⁄h (Note 1). Usually, 12 h or more is needed to

obtain a balance with the apparatus after a deﬁnite change is

made in the hot-face temperature.

NOTE 1—Signiﬁcant errors will result if the tolerances speciﬁed are

exceeded.

7.3 After the steady state of heat ﬂow has been reached,

measure the temperature of the test specimen, the rate of water

ﬂow through the calorimeter, and the temperature rise of the

water ﬂowing through the calorimeter. Take at least four sets of

readings at approximately 30-min intervals during the 2-h

holding period, and average these for the ﬁnal values for that

particular heating chamber temperature.

Alundum Cement RA 562 supplied by the Norton Co., One New Bond St.,

Worcester, MA 01606, is satisfactory for this purpose.

FIG. 1 Arrangement of Refractory Fiber Paper Strips in Calorim-

eter Assemblage

C767 − 20

7.4 At the conclusion of the test, examine the specimens for

changes which may have taken place as a result of the heat

treatment. Then remove the thermocouple wires, cut the brick

in half through the 4

⁄

by 2

⁄

-in. (114 by 64-mm) dimension,

and examine for voids and cracks.

8. Calculation

8.1 Make the record of test data, the calculations, and the

report in accordance with Test Method C201.

9. Precision and Bias

9.1 Refer to Test Method C201 for a statement of precision

and bias.

10. Keywords

10.1 calorimeter; carbon refractories; refractories; thermal

conductivity

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned

in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk

of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every ﬁve years and

if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards

and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the

responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should

make 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 above

address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website

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Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/

C767 − 20

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摘要：

ASTM C767 - 20 是一项由美国材料与试验协会（ASTM）发布的标准测试方法，专门用于测定隔热耐火砖在高温条件下的热导率。该标准适用于在900°C至1600°C（1650°F至2910°F）范围内使用的耐火材料，通过稳态热流技术评估材料的传热性能。对于从事高温工业、窑炉设计、陶瓷制造或建筑材料开发的工程师与质检人员而言，ASTM C767 - 20 提供了关键的数据支持，帮助优化材料选择、提高能效并确保设备在极端环境下的安全性。该标准的最新版本（2020年）更新了测试装置精度要求和试样

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