STUDY OF PORE STRUCTURE AND PERMEABILITY
OF TWO-DIMENSIONALLY REINFORCED CARBON-CARBON
COMPOSITE MATERIAL PREPARED BY ISOSTATIC
D. V. Yartsev
and S. A. Kolesnikov
Translated from Novye Ogneupory, No. 8, pp. 30 – 34, August, 2012.
Original article submitted May 21, 2012.
The pore structure and gas permeability of carbon-carbon composite material, prepared by isostatic carboniza
tion technology using coal-tar pitch are studied. Results of studying the pore structure are compared with those
for material prepared by pyrolytic carbon compaction technology. The change in average gas permeability is
presented in relation to material open porosity and temperature.
Keywords: density, open porosity, pore structure, pore size distribution, two-dimensionally reinforced com-
posites, isostatic carbonization, gas permeability.
Carbon-carbon composite materials (CCCM) are used
extensively in a number of branches of industry such as
space rockets, atomic, metallurgical, and they exhibit uni-
form refractoriness, higher thermophysical and mechanical
properties, higher heat resistance and chemical stability,
compared with traditional carbon-graphite materials. A dis-
advantage restraining use of CCCM in structures operating
under high-temperature and chemical action conditions of
some corrosive media in a number of cases is their perme
ability with respect to liquids and gases.
Permeability depends on material structural porosity and
is determined by the presence and size of pores and
microcracks, joining with each other and communicating
with a surface (channel pores). There is mass transfer of a
substance (filtration, diffusion) through these pores within a
porous body. Presence of developed porosity is a typical fea
ture of all carbon materials, including CCCM. The pore vol
ume is from 2 – 3% for materials with a density approaching
theoretical (pyrographite), and up to 90 – 95% for porous
structural materials. A considerable part of open porosity in
carbon materials is channel porosity, and this gives rise to
their permeability [1, 2]. The aim of this work is to study the
pore structure and permeability of CCCM of
two-dimensionally reinforced composites (2D-CCCM),
based on carbon cloth (the textile structure is a fabric) of
combined thread VMN-4 (reinforcing fibre filler) and
coal-tar pitch coke (carbon matrix).
A feature of the test material is its preparation by iso-
static carbonization technology of a carbon-carbon base,
similar to technology for producing unidimensionally rein-
forced CCCM of the Desna type. The production cycle for
preparing 2D-CCCM includes lay-up of cloth layers or wind
ing cloth on a mandrel, multistage impregnation with me
dium-temperature coal-tar pitch followed by carbonization
of each impregnation, mutltistage impregnation with high-
temperature coal-tar pitch followed by operations of isostatic
carbonization and high-temperature treatment (HTT) after
each impregnation, and billet machining. Objects and billets
of 2D-CCCM are presented in Fig. 1.
The pore structure of materials was studied in the main
production stages. Experimental results for the value of ap
parent density r
, and open porosity P
, %, were
obtained by the MI 002008551-313–2007 OAO NIIgrafit
procedure using a substitution medium of standard iso-oc
tane (GOST 12433). The specific pore volume V,cm
nature of its distribution with respect size of equivalent pore
, mm, were studied by mercury porisimetry .
The equipment formulation has been presented in , and
typical test results are provided in Table 1.
A histogram is shown in Fig. 2 for the distribution of val
ues 2D-CCCM of P
, with density of 1.81 – 1.88 g/cm
In spite of the fact that the histogram has an asymmetric
shape, and a steeper drop is observed towards greater values
Refractories and Industrial Ceramics Vol. 53, No. 4, November, 2012
1083-4877/12/05304-0246 © 2012 Springer Science+Business Media New York
OAO Scientific-Research Institute of Structural Materials Based
on Graphite NIIGrafit, Moscow, Russia.