AN ANALYSIS OF THE EFFECT OF SYNTHETIC CONDITIONS
ON PROPERTIES OF GLASS CERAMIC MATERIALS:
A MATHEMATICAL MODEL FOR SIMULATING THE THERMAL
TREATMENT OF LITHIUM ALUMOSILICATE GLASS AND CERAMIC
E. I. Suzdal’tsev
and V. I. Kurakin
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 9, pp. 37 – 41, September, 2001.
A mathematical model for simulating the thermal treatment of lithium aluminosilicate glass and lithium alu
minosilicate-based glass ceramic is proposed. The model allows one, given a set of input process parameters,
to evaluate the output parameters characterizing the quality of the processed material. Using this model, econ
omy in effort and time for optimizing the thermal treatment of glass ceramic materials and in experimental
costs is achieved.
Thermal treatment of glass-ceramic materials is targeted
at solving three major problems. It provides conditions, first,
for maximum nucleation; second, for the required degree of
crystallinity, and third, for the specified phase composition of
glass ceramics. Furthermore, an important technological re-
quirement for the heat-treatment cycle is its short duration.
Theoretically, the heat-treatment regime for b-spodu-
mene-based glass ceramics can be represented by a sche-
matic diagram as shown in Fig. 1. The exact specification of
regime parameters (heating and cooling rates, nucleation
temperature, upper-limit crystallization temperature, and
holding times) is of exceptional importance for glass-ce
ramic technology as concerns the assurance of optimum phy
sicomechanical properties of the material, the large-scale
production of finished products, and the cost-effectiveness of
the fabrication process .
Still, no appropriate criterion — except the required set
of properties — has been proposed that would allow optimi
zation of the heating regime for a material of specified chem
ical composition. Therefore in most cases the heating regime
is established experimentally, by a trial-and-error method, by
an extensive search for different variants. Although this pro
cedure requires much time and effort, its importance cannot
be underestimated considering that each heating-regime pa
rameter plays a role in forming the structure and properties
of the material synthesized [2 – 8].
For example, the heating rate is controlled by a range of
factors such as (i) the strain in the material, when, at a high
heating rate, the crystalline framework — in fact, the rein
forcement of the material — fails to form completely; (ii) the
possible fracture of the material when, because of the rapid
heating, a through-the-thickness temperature gradient is ge-
nerated leading to stresses exceeding the ultimate strength of
the material; (iii) the possible fracture at rapid heating owing
to substantial changes in the bulk of individual crystalline
phases, when stresses between the crystalline phases and the
glassy phase have not had time to relax; (iv) the limitations
of the processing equipment, especially in the mass produc-
tion of large-sized components.
Other factors that may affect substantially the quality of
end products are the nucleation temperature, upper-limit
crystallization-temperature, and the holding time at a given
Refractories and Industrial Ceramics Vol. 42, Nos. 9 – 10, 2001
Tekhnologiya Production and Research Enterprise, Obninsk,
Kaluga Region, Russia.
Fig. 1. A theoretical regime for thermal treatment of the glass mate
rial used for fabrication of glass ceramics: A ) nucleation tempera
ture; B ) upper-limit crystallization temperature.
1083-4877/01/0910-0321$25.00 © 2001 Plenum Publishing Corporation