ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 3, pp. 382−385. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © Ya.I. Vaisman, A.A. Ketov, Yu.A. Ketov, R.A. Molochko, 2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 3, pp. 375−378.
INORGANIC SYNTHESIS AND INDUSTRIAL
Oxidation of Carbon by Water Vapor in Hydrate Gas-Formation
Mechanism in Manufacture of Cellular Glass
Ya. I. Vaisman
, A. A. Ketov
, Yu. A. Ketov
, and R. A. Molochko
Perm National Research Polytechnic University, Komsomolskii pr. 29, Perm, 614990 Russia
Perm State National Research University, ul. Bukireva 15, Perm, 614990 Russia
Received April 6, 2015
Abstract—Gas formation in production of a cellular glass is considered for the case when the hydrate mechanism
is operative and water vapor is used as oxidizing agent. It is shown that the presence of carbon in the system leads
to a steam conversion and larger volume of released gases. Differences in the structure of materials obtained
with different carbon reducing agents and formation depth of polysilicates in the raw material are discussed. It
is shown that a light cellular glass can be obtained.
Porous glasses with closed cell structure and densities
lower than 250–300 kg m
are rather attractive as
functional heat-insulating materials, especially in the case
when waste glass is used as a raw material. Commonly,
the gas formation in the thermoplastic state is provided by
melting a special glass with addition of special reagents.
Conventionally, a sulfate-containing glass and a powder
technique of its thermal treatment are used . However,
the procedure for melting of special glasses entails higher
energy expenditure for obtaining the ﬁ nal product and
providing carbon dioxide emission.
To obtain a cellular glass, it is necessary to select the
conditions in which the gas-formation process occurs
at temperatures higher than the softening and sintering
points of the glass powder, which corresponds in the
case of a sodium-calcium glass to temperatures above
923–973 K. It is possible in this case not only to use a
glass containing a component of a redox pair, but also to
add a compound that undergoes a thermal dissociation,
e.g., manganese oxide MnO
as suggested by the authors
of . The authors could secondarily use, together
with the sodium-calcium glass, ﬁ berglass. The thermal
treatment temperatures of the formulation were in the
range 1173–1323 K.
However, the conventional sodium-calcium glass
exhibits a hydrothermal activity, especially at a high
dispersity of the material. This property can be used
to process waste glass into functional materials [3, 4].
Hydration of silicates in the glass at high pressure or
temperature makes it possible to obtain composites
capable of releasing water vapor at high temperatures,
thereby expanding the silicate composite, which is in
the thermoplastic state under these conditions. The
composition-dependent thermal plasticity of a composite
determines the water release and composite expansion
temperatures. The authors of [5, 6] demonstrated the
possibility of expanding the material produced from
a sodium-calcium silicate glass under a hydrothermal
treatment at temperatures of about 923 K.
There is a technical opportunity for at all excluding
the hydrothermal treatment of a dispersed glass if this
glass is used as ﬁ ller in a composite material and the
intergranular space is ﬁ lled with synthetically hydrated
sodium polysilicates . In this case, synthesis of glass in
the intergranular space at temperatures close to that in the
case described above also lead to release of water vapor
and expansion of the composite without hydrothermal
treatment of the dispersed glass.
Because polysilicate structures are formed in
hydration and dehydration processes of composites
that are not described by the Gibbs rule of phases and
formally are nonstoichiometric, water vapor is released in