VOL 84, No. 7 (2011)

Influence of substitution of sodium cation by barium and calcium on the structure of sodium borosilicate glass of composition: 0.25 Na ₂ O; 0.25 B ₂ O ₃; 0.5SiO ₂. Analysis of the recorded spectra showed that the replacement of the Na ⁺ cation with alkaline earth metal cations, Ba ²⁺ and Ca ²⁺ leads to the rupture of B-O- bridges. В and Si-O-Si, as a result of which the proportion of terminal oxygen atoms increases and the degree of glass polymerization decreases. Tab. 1, ill. 4, bibliography: 13 titles.

In the Bi ₂ O ₃ - SiO ₂ - P ₂ O ₅ system the range of molar content 57.1% Bi ₂ O ₃, 42.9 - 17.1% SiO ₂, 0 - 25.7% P ₂ O ₅ transparent glasses were obtained. The effect of the P ₂ O ₅ content on the melting temperature and glass color has been established. Such glasses are promising for use in photonics and as scintillation materials. Tab. 2, ill. 1, bibliography: 7 titles.

The sintering process of powder workpieces based on oxide ceramics is considered from the standpoint of diffusion mass transfer. In practice, two types of powders are used, differing in manufacturing methods. As a rule, the coarser-grained of them is traditionally obtained by mechanical grinding, another, characterized by a high degree of dispersion and a high content of various kinds of defects in the crystal lattice of particles, by chemical methods, such as precipitation from solutions, heterophase interaction, cryo- and plasma-chemical treatment, etc. .d. It is shown that during sintering of billets, their compaction and hardening is carried out according to various physical mechanisms. Bibliography: 14 titles.

The results of mathematical modeling of the process of ceramic molding by hot casting are presented. The calculated data describe changes in the state of aggregation of a thermoplastic slip as it cools in the forming cavity. Foundry characteristics are obtained that ensure uniform properties of a thermoplastic slip when molding ceramics by hot casting. Il. 5, bibliography: 7 titles.

The issues of thermal dissociation of silicon and iron oxides, which are part of corundum-sillimanite ceramic molds, which are used for casting with heat-resistant alloys at high temperatures, are considered. Theoretical studies have determined that the silica, which is part of the ceramic mold, has a low resistance to thermal dissociation at 1873 K. It has been established that iron oxide will intensively evaporate in the melting zone in the range at a reduced pressure of 0.65 - 1.33 Pa. This phenomenon increases the reactivity of the ceramic mold in the zone of contact with heat-resistant alloys and is one of the sources of contamination of the cast surface. Tab. 1., bibliography: 3 titles.

The substantiation of the use of an aqueous solution for extinguishing fires containing 5 - 10% liquid glass is given. When water evaporates from the solution on the combustion surface, the liquid glass forms a viscoplastic insulating film, which foams under the action of high temperature and forms a porous insulating layer of inorganic foam. Tab. 1, bibliography: 4 titles.

The method of burnout additives was used to obtain porous ceramics based on kaolin, talc and quartz-feldspar raw materials of the Amur Region. Waste of rubber products, grain crops, woodworking industry was used as a pore-forming additive. For the samples obtained, open porosity, water absorption, specific surface area, compressive strength, and water permeability were determined. The apparent density, total and closed porosity, specific pore volume, and modulus of elasticity were calculated. Tab. 1, ill. 4, bibliography: 3 titles.

Prospects for the use of car tires processed into crumb rubber in the production of building ceramics are considered. On the basis of experimental data and preliminary statistical calculations, it was found that the addition of crumb rubber in the amount of 5 - 10% leads to changes in the values ??of physical and mechanical properties and structural parameters of ceramic samples. During the heat treatment of ceramic samples, the analysis of the composition and the amount of emitted gas was investigated. It was found that the additive used insignificantly affects the phase composition of ceramic samples. The use of crumb rubber makes it possible to obtain samples with satisfactory properties and to dispose of polymer waste. Tab. 3, ill. 6, bibliography: 8 titles.

By the method of high-temperature X-ray diffraction, the presence of a reversible polymorphic transformation of both synthesized stoichiometric leucite and precipitated as a result of crystallization of glasses was established. The established temperature limit of this transition for leucite, which is in the composition of glass-crystalline material, shifts to a region of lower temperatures in comparison with the modification transition of synthetic leucite. Il. 2, bibliography: 9 titles.