QUALITY AND CERTIFICATION
STUDY OF HEAT INSULATION MATERIAL THERMAL CONDUCTIVITY
BY A HOT-WIRE METHOD
M. A. Vartanyan,
R. I. Gerasimov,
O. V. Pyren’kin,
I. B. Dolbilova,
A. V. Oistrakh,
and A. A. Somov
Translated from Novye Ogneupory, No. 6, pp. 67 – 68, June, 2016.
Original article submitted May 23, 2016.
The possibility is considered of using a hot-wire method (cross-array method) for determining heat insulation
material thermal conductivity at high temperature. These tests show that different indices obtained by the
hot-wire method and the steady-state standard do not exceed 12 – 15%.
Keywords: thermal conductivity, hot-wire method, heat insulation materials.
In recent years instead of steady-state methods for deter-
mining thermophysical properties (in particular thermal con-
ductivity) for ceramic refractory materials of different desig-
nation there is more frequent use of transient methods, i.e., a
probe method (heated thread), a method of uniform heating,
and a thermal wave method. A hot-wire method is a version
of the probe method, and it has been used extensively for de-
termining refractory thermophysical properties over a signif
icant temperature range.
The hot-wire method is based on features of heating inor
ganic material within which a thin thread is placed, heated by
a direct electric current. Advantages of the method in deter
mining refractory thermal conductivity are the simple speci
men shape (brick or part of it in the form of a parallelepiped),
absence of limitations for test material thermal conductivity,
and the possibility of limiting to one temperature sensor. It is
also important that in a test the working change temperature
and material thermal conductivity is determined under condi
tions similar to those during refractory object operation in a
furnace. The measurement error is low (5 – 10% for heat in
sulation materials) and depends on quality of specimen tem
perature control, its thermal conductivity, and measurement
precision. The hot-wire method may with satisfactory accu
racy determine thermal conductivity with low values, i.e.,
from 0.05 to 2.5 W/(m·K); by the GOST 12170 procedure
the lower limit for hot-wire method determination of
refractories is 0.18 W/(m·K). This method is convenient for
determining thermal conductivity of granular and powder
refractories. Inadequacies of the method limiting its applica-
tion are significant (up to 15 – 20%) measurement error in
testing dense refractories with high thermal conductivity
(more than 2.5 W/(m·K)), and increase in requirement for
operator qualification and also the complexity of precise
control of specimen temperature during isothermal exposure.
It is difficult to use this method for determining the thermal
conductivity of anisotropic material . At the same time, an
advantage of the method is its use in testing heat insulation
refractories and this has made it possible to recommend it as
an international standard (ISO 8894).
Within the D. I. Mendeleev RKhTU faculty of chemical
technology of ceramics and refractories a test unit has been
developed in which one version of the hot-wire method is
implemented, i.e., a cross-array method with the possibility
of performing tests up to 1200°C. Previously by means of
this unit research was carried out for heat insulation
chamotte refractories . Satisfactory convergence has been
obtained for values of effective thermal conductivity with in
dices for materials of this type determined in a steady state
regime, and the measurement error is not more than 10%.
Recently the cross-array method has been used for determin
ing the effective thermal conductivity of heat insulation ma
Refractories and Industrial Ceramics Vol. 57, No. 3, September, 2016
1083-4877/16/05703-0332 © 2016 Springer Science+Business Media New York
FGBOU VPO D. I. Mendeleev, Russian Chemical Technological
University, Moscow, Russia.
OOO PKF Tsemogneupor, Podol’sk, Moscow Region, Russia.
OOO Teplopromproekt, Moscow, Russia.