VOL 74, No. 12 (2001)

The structure of glass quenched with phosphorus has been studied using the methods of positron annihilation, X-ray phase and electron microscopic analysis, depending on the thermal prehistory. Structural differences were found depending on the wall thickness of the product and the temperature regime of annealing. The method is proposed to be used for express analysis of the homogeneity and degree of annealing of opaque glasses. Tab. 1, ill. 4, bibliography: 4 titles.

A method for calculating characteristic temperatures, performance indices and physical and chemical properties of container glasses, based on the use of calculated exposure factors, has been developed. The calculation method can be used both in production and in educational and research practice. Tab. 3, ill. 1, bibliography: 7 titles.

The influence of the coordination groups of boron, aluminum and silicon on the acid-base properties and the peculiarities of changes in the redox state of copper in boron-containing melts has been investigated. An approximate assessment of the acid-base properties of industrial glasses synthesized in an alkali-aluminum boron-silicate system has been carried out. Tab. 5, ill. 3, bibliography: 12 titles.

Experimental data on the effect of crystal size on high-temperature deformation in the field of mechanical forces of ceramic oxide materials are presented. It is shown that the main creep occurs by the mechanism of bulk diffusion of vacancies of impurity or nonstoichiometric origin (from the inner regions to the boundary). Il. 7, bibliography: 15 titles.

The thermostimulated luminescence (TSL) of BeO powders and ceramic samples obtained from the same batch of powder with a density of 2.10 - 2.93 g / cm ³ has been investigated. It was found that with an increase in the density of the BeO samples (respectively, with the average size of microcrystals), as well as with an increase in the vacuum in the cryostat chamber, a change in the position, number, and intensity of low- and high-temperature TSL peaks of adsorption and non-adsorption nature is observed. It is assumed that both impurity and adsorption centers of bulk and surface origin and intrinsic lattice defects are responsible for the formation of TSL centers in BeO powders and ceramics of various densities. Tab. 1, ill. 1, bibliography: 16 titles.

The kinetic parameters of mullite formation from oxides in the presence of mineralizers (B ₂ O ₃ and AlF ₃) and with the addition of kaolinite (20%) have been studied experimentally. The degree of completeness of reactions, activation energy and rate constants for the reaction of mullite formation in different mixtures have been determined. It was shown that AlF ₃ and kaolinite have the greatest accelerating effect. Tab. 1, ill. 2, bibliography: 8 titles.

The possibility of the formation of low-melting glasses in the system R ₂ O - RO -Al ₂ O ₃ - B ₂ O < sub> 3 - TiO ₂ - P ₂ O ₅ at a firing temperature of 550 ° C. The dependence of glass formation in the considered system on the content of Al ₂ O ₃ and P ₂ O ₅ and the composition of the transition layer with crystalline phases Na ₂ O * P ₂ O ₅, Al ₂ O ₃ and Al ₂ O ₃ * P ₂ O ₅. Tab. 2, ill. 2, bibliography: 3 titles.

The stability of basalt and aluminoborosilicate fibers of different diameters under the influence of an alkaline medium of hydrating cements (concretes) has been investigated. Kinetic dependences of absorption by CaO fibers from a saturated solution of Ca (OH) ₂ are given. The general regularities of the change in the tensile strength of the fibers after holding in the specified solution for 3, 6, and 12 months have been revealed. The data obtained can be used to analyze and derive the calculated dependences of the long-term strength of basalt fiber composites based on cement matrices. Tab. 3, ill. 4, bibliography: 1 title.