Processing of industrial waste by plasma-chemical method

In this paper, the results of the processing of magnesium fluoride by plasma-chemical method to obtain periclase and a solution of hydrogen fluoride (hydrofluoric acid) were presented. For the industrial implementation of plasma technologies, it is necessary to study the main parameters of plasma processes for obtaining reducing gases and processing metal oxides with them, to solve the issues of their hardware design, to increase the service life of plasma torches for their use in continuous metallurgical processes. The purpose of this work was to determine the conditions for the plasma-chemical process of processing magnesium fluoride. Thermal analysis of magnesium fluoride on a TGA/DSC2 thermogravimetric analyzer was performed. Thermogravimetric analysis showed that in the temperature range under consideration the process is endothermic, and at a temperature of ~1280°C a phase transition of the 1st kind is observed due to the melting of magnesium fluoride. The fractional composition of MgF2 and MgO powders was studied using the Analysette-22 Nanotech laser diffraction analyzer. The results of the evaluation of the fractional composition of powders have a significant difference. At the same time, the convergence of the data obtained using laser diffraction and electron microscopy methods was found

Physical and Chemical Processes of Structure Formation of (BeO+TiO2)-Ceramics with the Addition of TiO2 Nanoparticles

This paper describes in detail the solid-phase sintering mechanism of BeO + + ceramics in the 1520–1550 °C temperature range. It is shown that the structural elements are formed due to the processes of pore disappearance and grain growth in the process of ceramic shrinkage during sintering. It is found that under the influence of TiO2 nanoparticles it is possible to increase the sintering temperature of such ceramics by 30 °C, which promotes the transformation of the crystal structure of TiO2 into a more conductive Ti3O5 with an orthorhombic structure. The mechanism of the slowing down of the grain boundary movement by the second phase impurity as the segregation of nano impurities on the grain boundary is described. The calculation of binding energy of spontaneous chemical reactions during sintering of ceramics is performed, chemical elements and compounds related to conductive phase in ceramics of BeO + + composition at sintering temperature 1550 °С are determined. It is shown that the specific conductivity of the synthesized nanocomposite material increases in comparison with the ceramics consisting of micropowders in the frequency range of 100 Hz–100 MHz, at a sintering temperature of 1550 °С

Microstructure and mechanical properties of HA/Ti composite coatings applied by detonation spraying

This work presents the results of experimental studies of the structure and mechano-tribological properties of composite coatings based on hydroxyapatite (HA) and titanium in different ratios (wt. %): 30HA-70Ti, 50HA-50Ti, 70HA-30Ti. Composite coatings with a thickness of 40-50 μm were applied to a substrate made of Grade 2 titanium by detonation spraying. Microstructures and phase compositions of as-sprayed coatings were analyzed by scanning electron microscopy and X-ray diffraction. The deposition mechanism of HA-Ti composite coatings was also examined. The results of the study showed that during detonation powder spraying from a mixture of HA-Ti, porous coatings are formed, consisting of the phases of hydroxyapatite Ca10(PO4)6(OH)2, tricalcium phosphate, titanium, and titanium oxide. It was found that with a decrease in the content of hydroxyapatite in the composite, there is a decrease in the relative content of B-type carbonate ions in the structure, as well as a decrease in the content of the mineral phase as a whole. Composite coating 30HA-70Ti wt. % is the closest in structure to stoichiometric crystalline HA (Ca/P = 1.67). At ratios of coatings 50HA-50Ti wt. %, an increase by 1.5-2 times in wear resistance is observed