Analysis of methods for increasing the oxidation resistance of carbon-graphite products used in metallurgical and chemical units

Abstract

This review study analyses the existing methods for increasing the oxidation resistance of carbon-graphite products, as well as assesses their applicability in metallurgical and chemical units. The reseach basis was the data published on the oxidation mechanism of carbon-graphite materials, conditions for their use in metallurgical and chemical processes, as well as existing technologies aimed at improving the oxidation resistance of artificial graphites. The existing ideas about the kinetics of carbon graphite oxidation are described depending on temperature conditions. A review of existing technologies for increasing the oxidation resistance of materials and their economic efficiency, taking into account the conditions of their operation, was carried out. Prospects of the presented solutions for the units of metallurgical and chemical industries were analysed. Three modes of oxidation of graphitised materials were distinguished on the basis of operating conditions, chemical and physical properties. According to this classification, the most rational method for increasing oxidation resistance consists in the impregnation of carbon-graphite materials with the formation of a protective glassy coating in the volume of through pores or with the formation of a coating (a continuous layer on the surface of the product) due to the occurrence of a chemical reaction with the reagents used. For most metallurgical and chemical units, the impregnation of carbon-graphite materials with the formation of borate and phosphate glasses is preferable, primarily due to lower economic costs. The applicability of this method is currently limited by temperature conditions, at which the protective properties and continuity of the formed glassy coatings are preserved. Therefore, additional research is required to adapt the conventional technological and technical solutions to the high-temperature conditions of metallurgical units (over 800°C).