1070-4272/01/7412-1990 $25.00 C 2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 12, 2001, pp. 1990!1993. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 12, 2001,
Original Russian Text Copyright + 2001 by Vakhula, Yashchishin, Vasiichuk, Romaniv, Semchuk.
AND INDUSTRIAL INORGANIC CHEMISTRY
Specific Features of Preparation of Liquid Glass-Based
Colloid Solutions for Synthesis of Glass Coatings
Ya. I. Vakhula, I. N. Yashchishin, V. A. Vasiichuk, A. S, Romaniv, and O. R. Semchuk
L’vovskaya Politekhnika State University, Lviv, Ukraine
Received March 28, 2000; in final form, June, 2001
Abstract-Conditions for obtaining stable colloid solutions for synthesis of alkali-silicate glass coatings based
on lithium, sodium, and potassium liquid glass were studied. The influence of the solution pH and the nature
and concentration of liquid glass on the gel formation was established.
The sol-gel method is one of the most promising
and universal among a number methods for obtaining
glass coatings. In many cases, sols [1, 2], colloid solu-
tions [3, 4], gels, or their dried powders [5, 6] are
used. The choice of a specific solution state or solu-
tion-based products for the formation of glass coatings
depends on a support material and its final destina-
tion. In each case, the technological process starts
from solution preparation. The preparation of a highly
homogeneous and stable solution with required com-
position and concentration is an important and com-
The main problem in obtaining homogeneous col-
loid solutions based on liquid glass arises from
the fact that addition of even insignificant amounts
of solutions of IIA and IIIA group elements to silicate
solutions breaks the homogeneity of the correspond-
ing systems due to the formation of difficulty soluble
silicates of most of metals. Obviously, addition of
boron-containing compounds gives rise to precipita-
tion of amorphous silicic acid.
It is known [1, 7] that the ability of colloid solu-
tions to be in fluid state for a long time determines
their stability and depends on a number of factors,
in particular, on their composition, concentration, pH,
and the order of component mixing. Therefore, the
conditions of solution preparation are of paramount
The aim of this work was to find optimal compo-
nent concentrations and technological parameters for
obtaining high-quality colloid solutions for synthesis
of coatings of various technical destinations.
Boron aluminosilicate glasses and, in some cases,
silicophosphate glasses form the base of the majority
of glass coatings. Thus, the main problem is to obtain
a colloid solution containing liquid glass, aluminum
salts, and also salts of boric and phosphoric acids.
A specific character of silicates of alkali metals re-
quires use of an unconventional approach to the choice
of aluminum-, boron-, and phosphorus-containing
compounds for obtaining stable colloid solutions.
These compounds must satisfy a number of require-
ments: 1) absence of reactions with alkali metal sili-
cates resulting in the formation of heterogeneous sys-
tems; 2) high water-solubility and low decomposition
or melting point; 3) high content of a required oxide
, etc.) in solution.
A glass formed in the system Na
is used for obtaining protective corrosion-
resistant coatings. Sodium and potassium liquid glasses
with a modulus of M =234 were used as bases for
preparation of colloid solutions. The concentration of
alkali metal silicates was 5.5 310 wt %.
Hydroxoaluminates are appropriate for use as alu-
minum-containing compounds. It is the hydroxo com-
] or similar compounds that
are alkali metal aluminates obtained in solutions.
Therefore, we further use the general formula
] for alkali metal aluminates. The com-
position of a resulting compound depends on pH and
the concentration of reacting solutions.
As shown in , among boron-containing reagents,
only boric acid meets the above-mentioned require-