SPECIFIC FEATURES OF THE STRUCTURE OF FILTERING
S. M. Logvinkov,
G. D. Semchenko,
D. A. Brazhnik,
and L. P. Gurenko
Translated from Novye Ogneupory, No. 6, June, 2004, pp. 34 – 38.
Original article submitted March 1, 2004.
The use of cordierite for preparation of filtering ceramic materials is discussed. Phase composition and struc
ture of permeable sintered cordierite-containing ceramics are considered. Results of a study of cordier
ite-based “honeycomb” materials used in the high-temperature catalytic conversion of methane are presented.
The newly designed ceramic catalyst carriers are shown to conform with service requirements.
In recent years on the market of porous ceramic materi-
als, there has been the growing demand for permeable ce-
ramics (of filtering type), in contrast to the decreased con-
sumption of heat-insulating ceramics. The products of inter-
est (in decreasing service order) are: materials for macro and
microfiltration, high-temperature catalyst carriers, “honey-
combs” (components of transtropic symmetry with channels
of different configuration along an axis of symmetry that are
used as catalyst blocks and substrates for ceramic ultrafiltra-
tion membranes, ceramic bioimplants, substrates for immo-
bilized microorganisms, and gradient-porous and special
Production of ceramic permeable materials and compo
nents requires the use of advanced technologies; despite the
stringent technological requirements, the share of these prod
ucts in the total of metallic and organic permeable materials
is increasing continually owing to their high corrosive resis
tance and ability to operate at high temperatures. Manufac
ture of permeable ceramics is a complex process; typically, it
is effected in several steps and is controlled by many factors,
which poses problems with the reproduction of structural and
operating properties. The most critical technological opera
tion in the synthesis of ceramics is the sintering, which is
central for the final buildup of structure, phase composition,
and properties of a material or a component.
Cordierite is a triple oxide that forms in the MgO – Al
system. Cordierite, owing to its specific features, is a
promising precursor material for permeable ceramics.
1. The crystal structure is represented by columns of
six-membered rings of alumosilicate tetrahedra whose di-
mensions allow adsorption of CO
, water, and inert gases
2. Cordierite has a low thermal linear expansion coeffi-
cient (TLEC), which provides stability of its porous structure
at high temperatures and resistance under variable thermal
3. Precursor materials for the synthesis of cordierite are
readily available, and its production can be organized on a
4. Cordierite has a high corrosive resistance and is toler
ant to oxides (for example, ZrO
and NiO), carbides (SiC),
and nitrides (Si
) at high temperatures.
5. Synthesis of cordierite involves strictly controlled re
versible solid-phase reactions in the MgO – Al
system; kinetically and thermodynamically conjugated oscil
lating processes at different temperatures provide self-orga
nization of the phase composition and structure of the mate
rial. Synthesis of heterophase cordierite-containing materials
(for example, composed of corundum, mullite, and cordier
ite) can provide a route towards the targeted modification of
structure and properties, such that would allow control of
heat flows under thermal loading not only through dissipat
ing heat to the surroundings, but also by consuming heat to
sustain thermodynamically unfavorable solid-phase pro
cesses (reversible reactions).
6. Cordierite-based refractory materials can be prepared
using relatively low-temperature sintering regimes.
All these features make cordierite-containing permeable
ceramic materials promising candidates for the multifunctio
nal application in “honeycombs” – catalyst carriers for the
Refractories and Industrial Ceramics Vol. 45, No. 5, 2004
1083-4877/04/4505-0333 © 2004 Springer Science + Business Media, Inc.
National Technical University (Kharkov Polytechnical Institute),