No abstract

the aim of the work is to study the effect of a high-temperature plasma torch on the processes of phase transformations and layer-by-layer modification of the protective and decorative coating on concrete using as a filler a mixture of quartz sand and hollow glass microspheres. The main tasks included: investigation of the processes of evaporation and thermal diffusion of oxides of plasma-coated coatings; study of phase transformations in the melt and its subsequent crystallization in the process of rapid spontaneous cooling of the fused protective and decorative coating; study of the effect of sodium liquid glass on the processes of polymorphic transformations of alumina and the formation of micro-wicks due to the intense diffusion of sodium oxide; study of operational characteristics of protective and decorative coatings. It was established that the initial phases in the protective-decorative coating are α-Al2O3 and CaO∙6Al2O3 (β-Al2O3), and the liquid sodium glass in the coating leads additionally to the formation of Na2O∙11Al2O3. The top layer of the protective and decorative coating is Na–Ca–Al–Si glass with regions of heterogeneities containing an increased content of sodium oxide. The content of aluminum oxide in the protective and decorative coating based on the battle of high-alumina refractory was 95.1 %. The introduction into the coating composition of sodium liquid glass minimizes the processes of dehydration of the binding component and changes the chemical composition of the protective and decorative coating. Reduction of the aluminum oxide content to 83.0 % affects the microhardness indicators. Microhardness of the concrete surface due to the introduction of liquid glass is reduced from 2510 HV to 887 HV.

This article presents the results of research on the sintering of molybdenite concentrate with magnesium-containing natural additives — brucite (Mg(OH)2) and magnesite (MgCO3). Physical and chemical properties of initial materials were studied. The thermodynamic assessment of the interaction of molybdenum with hydroxide and magnesium carbonate in an oxidizing medium is given. The process of thermochemical decomposition of molybdenum was optimized with usage of cheap magnesium-containing minerals to form molybdate and magnesium sulfate. The developed method makes it possible to reduce the cost of thermochemistry, to minimize the release of sulfur dioxide due to its rapid binding to magnesium sulfate.

No abstract