VOL 75, No. 4 (2002)

A not quite traditional approach to the problem of melting and subsequent glass transition of a silica melt, as well as to the problem of crystallization of quartz glass upon heating, is considered. It is shown that during the glass transition of the SiO ₂ melt, the enthalpy of the system remains almost constant until the glass solidifies. An estimate of the activation energy of the crystallization process of quartz glass is given. Il. 1, bibliography: 4 titles.

The influence of various factors on the redox potential of potassium borosilicate glasses has been studied. It is shown that this potential is formed under the influence of a number of oppositely acting factors, and often one of them is dominant. Thus, raw materials play a major role in the formation of the redox potential of highly alkaline glasses. When predicting it, one should take into account the nature and coordination state of acidic oxides. Tab. 1, ill. 2, bibliography: 7 titles.

The glass formation, structure, and physicochemical properties of glasses of the PbO - ZnO - B ₂ O ₃ -TeO ₂ system were studied. The dual role of lead ions in structure of glasses. It is shown that the coordination transition of boron ions correlates with the PbO concentration in the glass. The nonlinear dependence of the properties of glasses on their composition is due to structural rearrangements in the glass. Il. 4, bibliography: 10 titles.

The issues of sintering ceramics based on corundum with a eutectic addition of the MnO - Al ₂ O ₃ - SiO ₂ system from the standpoint of the evolution of its structure are considered. When sintering in the presence of a small amount of eutectic, the behavior of the system changes significantly before and after the appearance of the liquid phase. Before the formation of the liquid phase, the process is determined by the properties of the material in contact between the particles, after which the system becomes sensitive to the state of the contact surface between the solid phase and eutectic liquid. The latter is explained by the fact that the eutectic composition is practically saturated with respect to aluminum oxide. Tab. 1, ill. 2, bibliography: 12 titles.

The possibility of using high-calcium waste from chemical water treatment and a lithium-containing mineralizer in the production of ceramic tiles has been investigated. The processes occurring during their sintering are explained. Tab. 1, ill. 3, bibliography: 5 titles.

The results of obtaining highly dispersed cubic alumina by the method of chemical deposition from solutions of aluminum hydroxides with subsequent dehydration are presented. Il. 2.

Synthesized enamel glasses based on the Na ₂ O - B ₂ O ₃ - Co ₂ O _{3 system} - SiO ₂, including perlite, nepheline concentrate and broken glass. The physicochemical and technological properties of the obtained glasses and groundless coatings based on them have been studied. A comparative analysis of the fluxing effect of the compositions nepheline concentrate - glass breakage and perlite - glass breakage on glass is carried out. The areas of basic compositions suitable for the development of groundless powder glass enamels have been established. Tab. 2, ill. 2, bibliography: 4 titles.

Thin-film coatings based on zirconium and cobalt oxides have been obtained. It is shown that the properties of the coatings depend on the ratio of oxides in the film, the rotation frequency of the substrate, and the firing temperature. Films with a low cobalt content have the highest refractive index and significant adhesion. To cover the flasks of UV lamps, glass of window blocks to regulate the intensity of visible light and protect against UV radiation, it is advisable to use films with a molar content of cobalt oxide up to 60%. Tab. 3, ill. 2, bibliography: 6 titles.

The reasons for the occurrence of the most common defects in glazing of concrete (reinforced concrete) products are considered, possible ways to eliminate defects are indicated. Tab. 1, bibliography: 5 titles.

The possibility of utilization of galvanic sludge in the production of bricks has been investigated. The properties of the samples obtained meet the requirements of international standards. Il. 3, bibliography: 4 titles.

Clays of the Andreevskoe deposit (Ukraine) are high-quality raw materials suitable for use in the ceramic industry in the manufacture of a wide range of products - from sewer pipes to high-strength insulators. Tab. 1, ill. 1, bibliography: 6 titles.