VOL 78, No. 8 (2005)

Kinetic studies of the transformations of chromium oxides during heating of the charge and in the molten glass have been carried out. Various degrees of conversion of CrO ₃ and Cr ₂ O ₃ have been shown. The conditions for the equilibrium of chromium oxides in the glass melt in the case of their joint presence have been determined. The conditions for the interaction of chromium and iron oxides in molten glass, including in the surface layer, in which an equilibrium of coloring oxides can be achieved in accordance with the conditions of interaction and the composition of the gas atmosphere, have also been investigated. Low rates of interaction processes in molten glass are due to its high viscosity and low values ??of diffusion coefficients. Il. 6, bibliography: 6 titles.

Phase transformations in glass mixtures during compaction are considered. A method for calculating and constructing phase diagrams has been proposed, which makes it possible to visually represent the qualitative and quantitative phase changes associated with the physicochemical processes occurring in the glass batch at individual stages of granulation, as well as to actively influence these processes in order to obtain a product with specified technological properties. Tab. 2, ill. 2, bibliography: 5 titles.

The results of studies on the production of ceramic materials with low thermal expansion coefficients based on a matrix of cordierite-eucryptite composition are presented. Compositions that are promising for the production of heat-resistant ceramics with a thermal expansion coefficient of 0.058 x 10 ^-6 to -1.793x; 10 ^-6 K ^-1 and recommended for use in conditions of sharp thermal loading. Tab. 3. ill. 1, bibliography: 9 titles.

The prospects of using various methods of synthesis for obtaining high-purity complex oxides of alkaline and divalent elements and rare elements of groups IV and V of precisely specified chemical and granulometric compositions are analyzed. It is shown that only the sol-gel method with the use of inorganic precursors was used to obtain nanosized powders of narrow granulometric classes. Epitaxial coatings based on complex oxides can be synthesized by the sol-gel method using organic precursors or true solutions of compounds of the reacting components. Il. 1, bibliography: 28 titles.

The effect of the initial components, gelling agent additives, heat treatment and disaggregation conditions on the completeness of forsterite synthesis and powder morphology was studied. The colloidal method using silica sol and magnesium acetate solution provides the most stable and homogeneous sol, and after heat treatment - a highly dispersed powder without additional grinding. The selected technological modes, contributing to the completion of the synthesis. Controlling the synthesis temperature made it possible to obtain a powder with a particle size of less than 0.1 to 0.2 - 0.5 ?m and an aggregate size of 0.5 to 2 - 5 ?m. Tab. 2, ill. 5, bibliography: 8 titles.

The influence of individual and complex thinning additives containing superplasticizer C-3 on the rheological parameters of ceramic slip and its individual components is considered. A comparative analysis is carried out with a production complex additive containing an imported deflocculant - rheotane. The influence of the developed complex additives on the technological properties of the slip for the production of sanitary-ceramic products has been studied. Tab. 1, ill. 1, bibliography: 3 titles.

The analysis of the practical use of diamond-abrasive tools designed for fine grinding of flat surfaces of parts made of optical glass, sitall and ceramics, based on plate elements, making it possible to vary the filling factor of the annular zones and the entire faceplate. According to the results of comparative tests, the advantages of lamellar faceplates over patch plates are shown. Tab. 4, ill. 1, bibliography: 11 titles.

A classification of clay raw materials by mineralogical and technological varieties has been developed to assess its suitability for the production of ceramic bricks and expanded clay gravel. Depending on the quality, the raw materials are divided into seven varieties. Determination of the mineralogical and technological variety of clay raw materials makes it possible to reliably predict the quality of finished products without carrying out a large volume of laborious tests. Tab. 2, bibliography: 2 titles.