Уточнение строения системы CaO – Al₂O₃ – CoO

Abstract

Production of alumina cements using chemical industry wastes is an important direction for expanding the raw material base for the production of alumina cements. At the moment, it is possible to use in the composition of the raw mix for alumina cement, instead of alumina, a catalyst waste containing 80 % Al₂O₃ and 20 % CoO. For the use of cobalt-containing wastes, studies have been conducted to study the structure of the ternary system CaO – Al₂O₃ – CoO, which is the physicochemical basis for the development of compositions of aluminous cements based on the presented wastes. The article presents the characteristics of the binary subsystems and the ternary system CaO – Al₂O₃ – CoO. The results of the study of the subsolidus structure of the CaO – Al₂O₃ – CoO system without taking into account ternary compounds in solid-phase interactions are presented. The presence of a ternary compound in the system leads to a change in the subsolidus structure of the CaO – Al₂O₃ – CoO system. Graphic images of the system in the area of subsolidus are presented. The results of calculating the change in Gibbs free energy versus temperature for model reactions are presented. As a result of the conducted thermodynamic and geometrical - topological calculations based on the formed thermodynamic database, the data set the direction of mutual solid-phase reactions in the three-component CaO – Al₂O₃ – CoO system with the participation of stably existing compounds and the three-component compound Ca₃CoAl₄O₁₀, which made it possible to determine all connodes of this system. The main geometric topological characteristics of elementary triangles and system phases are calculated. Geometrical-topological characteristics of the system are technologically important for predicting the degree of accuracy of the dosage of the components, as well as the required time for mixing them before synthesizing materials with a given phase composition. The obtained results are necessary for the further analysis of solid-phase equilibria occur in the CaO – Al₂O₃ – CoO system.