Refinement of the subsolidus structure of the four-component system Fe₂O₃–CaO–Al₂O₃–Cr₂O₃

Abstract

The article describes the structure of the ternary subsystems of the four-component system CaO–Al₂O₃–Fe₂O₃–Cr₂O₃ . The calculations were performed with regard to three-component compounds. A tetrahedron of the four-component system CaO–Al₂O₃– Fe₂O₃–Cr₂O₃ has been plotted. The lengths of conodes and volumes of elementary tetrahedra were calculated. To study the relationship between elementary tetrahedra, a topological graph was constructed which allows using the obtained data in the study of oil-well cements based on this system. It has been established that the tetrahedron CaCr₂O₄–CaFe₂O₄–CaAl₂O₄–Ca₄Al₂Fe₂O₁₀ has the least degree of asymmetry (1.87), excluding some tetrahedra with simple oxides. The phases forming this tetrahedron most likely exist in the CaO– Al₂O₃–Cr₂O₃–Fe₂O₃ system. This will permit developing a sustainable process to fabricate oil-well cement materials based on the calcium aluminum-chromium cement without the use of special techniques to ensure high accuracy of dosing the initial components. In addition, when designing the compositions of binding materials, it is necessary to avoid the ternary compound localization area, because its coexistence with CaO will lead to the formation of portlandite in the cement clinker and to a significant decrease in the strength.