Production of target cathodes from composite silicides for applying protective coatings using casting and deformation technologies

The article discusses the results of manufacturing multicomponent consumable cathodes of vacuum electric arc evaporation plants. To obtain ingots of complex silicide as a raw material for the manufacture of target cathodes, it is proposed to use induction melting of pure metal charge materials in an argon atmosphere.The method made it possible to obtain ingots of complex silicide with a composition close to the calculated one and a density of at least 93 %. Further forming of the cathode takes place when controlling the powder fractions by their percentage ratio with a pressing force of at least 50 tons. The results obtained are compared with the SHS method of manufacturing cathodes of identical composition.

OXIDATIVE DIMERIZATION OF METHANE TO C2 HYDROCARBONS

The world's oil reserves are decreasing every day due to the continuous production and processing of the most modern technologies. Scientists all over the world are looking for various raw materials and methods to use the vast resources of natural gas as a substitute for petrochemicals. In this regard, great attention is drawn to natural gas as an alternative source of raw materials for petrochemical industries. The purpose of this work is to study the reaction of methane dehydrogenation on new 20%La-10%Ce20%Mg-50% glycine catalysts prepared by the SHS method to identify the optimal conditions for their preparation, concentration and ratio of metals, the influence of contact time and process temperature on the direction and mechanism of the reaction. The results of the study of 20% La-10% Ce-20% Mg-50% glycine catalyst prepared by the SHS method in the process of oxidative dehydrogenation of methane into C2 hydrocarbons are presented. On the basis of experimental studies, it was found that the composition of the catalyst exhibits high activity in the above reaction under the found optimal conditions. Thus, the influence of reaction temperature on the developed composition of catalysts for oxidative conversion of methane has been determined that the optimum temperature for the selective formation of ethane and ethylene is T=700o С. It was found that for selective oxidation of a mixture of CH4: O2 : Ar in C2 hydrocarbons the optimal conditions are: T=700o С, CH4:O2=2,5:1, 5000 h-1.

Synthesis of FeSi-Al2O3 Composites by Autowave Combustion with Metallothermic Reduction

Fabrication of FeSi-Al2O3 composites with a molar ratio of FeSi/Al2O3 ranging from 1.2 to 4.5 was conducted by the self-propagating high-temperature synthesis (SHS) method. The synthesis reaction involved metallothermic reduction of Fe2O3 and SiO2 by Al and the chemical interaction of Fe and Si. Two combustion systems were examined: one contained thermite reagents of 0.6Fe2O3 + 0.6SiO2 + 2Al, and the other had Fe2O3 + 2Al to mix with different amounts of Fe and Si powders. A thermodynamic analysis indicated that metallothermic reduction of oxide precursors was sufficiently exothermic to sustain the combustion reaction in a self-propagating mode. The SHS reaction carrying out co-reduction of Fe2O3 and SiO2 was less exothermic, and was applied to synthesize products with FeSi/Al2O3 = 1.2–2.5, while the reaction reducing only Fe2O3 was more energetic and was adopted for the composites with FeSi/Al2O3 = 2.5–4.5. Moreover, the former had a larger activation energy, i.e., Ea = 215.3 kJ/mol, than the latter, i.e., Ea = 180.4 kJ/mol. For both reaction systems, the combustion wave velocity and temperature decreased with increasing FeSi content. Formation of FeSi-Al2O3 in situ composites with different amounts of FeSi was achieved. Additionally, a trivial amount of aluminum silicate was detected in the products of high FeSi contents due to dissolution of Si into Al2O3 during the SHS process.

Utilization of dispersed waste of ferroalloy production on the basis of metallurgical SHS-process

A review of methods for processing dispersed waste from f loy production was performed. In ferroalloy plants there is a problem of formation and accumulation of cyclone dust (the catch product from crushing – CPC), formed during the grinding and fractionation of ferroalloys. The drawbacks of the known methods for the disposal of such dust are shown. The authors have investigated the possibility of obtaining commercial nitrided ligatures from CPC’s and substandard ferroalloy fines using the technology of self-propagating high-temperature synthesis (SHS). On the basis of the proposed “metallurgical” SHS method, a technology has been developed and the possibility of largescale production of nitrided ferrosilicon, ferrovanadium, ferrochrome and other materials has been shown, which has demand on the world market. Synthesized SHS materials are superior in quality to nitrided ferroalloys obtained by conventional furnace method, in particular, they have a lower content of oxygen, hydrogen and other impurities, and differ in better physical and mechanical properties: density, porosity, strength, and others. Based on the method of metallurgical SHS, the production of nitrided ferroalloys and composite ligatures with the possibility of processing up to 5000 ton per year of cyclone dust of ferrosilicon and other alloys was established in Russia, Magnitogorsk on the production base of scientific and technical production company LLC “STPF “Etalon”. A new approach to the practical implementation of the SHS method is developed and the possibility of using synthesis products in metallurgy is shown. The main application of these products is the use of alloying additives in smelting of a wide range of steels and alloys: transformer, rail, stainless, high-strength structural, and others. Another popular consumer of composite “metallurgical” SHS materials is the refractory production. Modification of traditional refractories used in smelting of cast iron, steel and non-ferrous metals with new composite SHS materials based on nitrides, borides, carbides and other refractory compounds can significantly increase the service life and reduce the expenses for refractories.