The study of technological peculiarities for improvement of chemical and physico-mechanical properties of reaction-sintered ceramic materials based on molybdenum disilicide

Abstract

Recommended ways to improve the chemical and physico-mechanical properties of reaction-sintered ceramic materials based on molybdenum disilicide have been described. In order to significantly increase the operating temperatures and change to more stringent operating conditions for ceramic products, it is necessary to improve existing methods of processing ceramics and significantly change the development of new ones. Various means for processing of ceramic materials have been studied and analyzed, which include the introduction of activating additives, hardening with dispersed particles, filamentary crystals and fibers and application of a protective coating to prevent rapid oxidation at surface layers. Carrying out partial purification of the initial starting components from various impurities can significantly increase some characteristics of the disilicide of molybdenum ceramics. Disilicide of molybdenum ceramics has been researched to have significant influence on the physical and mechanical properties (thermal conductivity, electrical resistance, coefficient of thermal expansion and strength) of molybdenum ceramics disilicides, which are introduced into the base material both with the initial components and in the process of its technological production. It has been established that it is possible to increase operating temperatures and ensure the use of molybdenum disilicide-based ceramic materials in harsher working conditions can be achieved by introducing of aluminum, boron, beryllium, iron, yttrium, nickel and cobalt powders into the charge, strengthening titanium coating, which includes silicification and titanium technology. It has been researched that at high temperatures and in the presence of molten silicon the synthesis and crystallization of molybdenum dicilicide occur on the grains in the surface layers, as well as dissolution and recrystallization of submicron particles of molybdenum dicilicide take place at certain depth. Based on the published data analysis and conducted research, the complex of measures for improving the chemical and physico-mechanical properties of reaction-sintered ceramic materials based on molybdenum disilicide has been proposed.