The successful development of a number of branches of socialist industry, and first of all of metallurgical industry, depends to a large extent on the quality of refractory ceramic products. Modern metallurgy, which uses oxygen blast in blast furnaces and high-speed methods of steelmaking in open-hearth furnaces, needs new, more highly refractory materials than the current ones, whose melting temperature does not exceed 1800- 2000°. The given data (see article) emphasize the great urgency of the problem of new highly refractory materials. The main reason for the difficulties arising in the search for new highly refractory materials is the lack of state diagrams of oxide systems that make up refractory masses. The number of materials from which refractory masses are usually made is rather limited. Therefore, the study of the previously unstudied state diagram of the system MgO - Cr2O3 - ZrO2 (melting point MgO - 2800 °, Cr2O3 - 2110 °, ZrO2 - 2715 °) can have not only theoretical but also practical value in the search for new refractory materials with higher physical and chemical properties. Triple mixtures of magnesium oxide, chromium oxide and zirconium dioxide, whose compositions are located in the region of solid solutions, as not forming eutectics and therefore do not experience softening when heated up to melting temperatures (2200-2600 °), are new, practically important highly refractory materials.
The essence of physicochemical analysis, created and formalized by Nikolai Semenovich Kurnakov into a special department of physical chemistry studying the equilibrium of various systems, consists in the application of physical methods to determine the chemical nature of substances formed in binary and multicomponent systems. The general method of physicochemical analysis consists in the quantitative study of the properties of equilibrium systems formed, depending on their composition, by two or more components. The result of the measured values is a composition-property diagram consisting of one or more lines, the positions of which determine the state of the system. The scientific works of the Kurnakov school were distinguished by their purposefulness and were mainly aimed at determining the characteristics of a chemical individual formed in binary and multicomponent systems in contrast to an ordinary solution of the same components. In other words, to determine how a substance that we can and should call a chemical individual differs from an ordinary solution of the components that form a chemical individual. The same question was posed to Proulx by Berthollet more than a hundred years ago, demanding a precise definition of both concepts. Dalton and Gay-Lussac, Wald and Ostwald were also concerned with this question.
