USING THE LATEST ELECTROPHYSICAL METHODS
FOR NONDESTRUCTIVE PROPERTY MONITORING
ON GRAPHITIZED CARBON MATERIALS
B. A. Kadyshkin,
E. Z. Kovarskaya,
I. B. Moskovenko,
A. L. Khait,
and A. M. Tsyv’yan
Translated from Novye Ogneupory, No. 11, pp. 58 – 61, November, 2008.
Original article submitted April 18, 2008.
It is possible to monitor the quality of graphitized carbon components by measuring the electrophysical prop
erties, which is demonstrated from experimental studies on the relation between the thermo-EMFs of carbon
fibers in relation to the normal elasticity modulus for a particular type of high-modulus carbon fiber. It is
shown that current devices can be used to measure the properties in making carbon items with continuous re
cording of the monitoring results.
Graphitized carbon materials are used in heating and
other forms of equipment, and their quality is subject to
fairly stringent requirements. Nondestructive test methods
can be employed in their production to provide prompt moni-
toring not only during production but also during use.
A basic quality criterion for a graphitized material is pro-
vided by the physicomechanical properties. To evaluate
those, standard methods based on manufacture and subse
quent testing of special specimens may also be accompanied
by nondestructive methods such as ultrasonic ones (instru
ments of the type of Pulsar and UK-10PM), as well as meth
ods based on natural frequencies of the items (instruments of
Zvuk, IChSK, and other types) . When one determines
those properties of high-modulus carbon fibers, one can also
use an ultrasonic method (instruments of UIMU type).
The properties of graphitized materials can also be
judged from the electrophysical parameters, since those
properties are substantially influenced by the structural char
acteristics. Tests have been done on the correlations between
structure, physicomechanical properties and electrophysical
properties, which show that it is possible to evaluate the
physicomechanical properties and the quality not only by di
rect measurement of those properties but also by measuring
the electrophysical ones. These data are based on researches
by S. V. Shulepov, A. I. Lutkov, R. M. Levit, A. A. Konkin,
V. Ya. Varshavskii, and various other researchers [2 – 13].
A carbon-base material may have conductivity of metal
type or semiconductor type. Also, the anisotropy in the prop-
erties of graphite substantially influences the electrical con-
ductivity. The electrical conductivity varies very widely in
solids. The bulk specific resistivity is 10
W×m for in-
sulators, while for full conductors it is less than 10
This means that electrophysical methods can be applied to
researching and monitoring graphitized carbon materials.
We consider that the most promising methods for moni
toring graphitized materials are the electromagnetic one
(eddy currents), and the thermoelectric and electrical-capac
ity ones. In the mid-1960s, the Soviet Union had developed
and routinely produced several types of electrical conductiv
ity meter, including the IE-20 for measuring the electrical
conductivity of graphite components by means of eddy cur
rents . Similar instruments were produced and are being
produced by foreign firms, but there has been no general use
of such instruments in Russian industry up to the present.
Most often, Russian industry employs instruments for mea
suring the specific resistivity of graphitized carbon blocks,
e.g., the portable four-probe UESMETR-5.
The Zvuk Corporation has collaborated with the Sintez
Scientific Center (Efremov Electrophysical Applications Re
search Institute) in testing various methods of determining
the electrophysical properties of graphitized materials as
used in the ITER diverter; at the same time, the physico
mechanical characteristics were determined by an acoustic
Refractories and Industrial Ceramics Vol. 49, No. 6, 2008
1083-4877/08/4906-0478 © 2008 Springer Science+Business Media, Inc.
Zvuk Corporation, St. Petersburg, Russia.