ВИВЧЕННЯ РЕАКЦІЙ ОБМІНУ В СИСТЕМІ SrO-BaO-Al2O3 -SiO2

Scientific research in the field of nanotechnology and composite materials for aviation and space technology contributes to the creation of new types of radio-transparent materials with improved properties. The need for these materials is especially growing in conditions of high temperature, high speed and aggressive external environment, where traditional polymer or composite materials cannot provide the necessary level of key properties. Ceramic materials made on the basis of target phases of the SrO-BaO-Al2O3 -SiO2 system have low dielectric properties and are quite promising for use in various fields where high transparency for electromagnetic waves with minimal losses is important. In this regard, a more detailed study of its subsolidus structure is relevant. This article deals with the flow of exchange reactions of the type аА+бВ = сС+дД in the volume of the SrO-BaO-Al2O3 -SiO2 concentration tetrahedron. The paper presents the results of Gibbs free energy calculations for exchange reactions in the considered system. The temperature intervals for the existence of separate combinations of phases are indicated and the formed elementary triangles are graphically presented. Based on the results of theoretical studies, it was established that in the SrO-BaO-Al2O3 -SiO2 system there is a possibility of five exchange reactions of the type аА+вВ = сС+дД. It was found that BaAl2Si2O8 – SrAl2O4 and Sr3Al2O6 – Ba2SiO4 anodes are present in the temperature range of 300...1700 K. The presence of a combination of "filled triangle" phases – Sr2Al2SiO7-2SrSiO3-BaSiO3 in the temperature range of 300...800 K was confirmed, and the existence of a combination of "filled circuit" phases – BaSiO3 – BaAl2O4 – Sr2Al2SiO7 in the temperature range of 1200...1700 K was confirmed. The discovery of this combination of phases makes it possible to expand the existing area in the experimental system for creating high-temperature ceramic materials. In turn, according to the obtained data of thermodynamic calculations, it was established that at temperatures below 1200 K, the target phases of the considered system, Ba2SiO4 and SrAl2Si2O8, do not interact with each other, and the reaction is thermodynamically disadvantageous.