The solid solution Ce0.8Y0.2O2-? was obtained by three methods: sol gel, glycine nitrate and solid-state reaction. The synthesis temperature was 1350 ?C for the sample obtained by the sol gel method and 1500 ?C for the remaining samples. It’s shown by the X-Ray method that all samples have a cubic lattice with a fluorite structure. The microstructure, density, electrical conductivity, microhardness and crack resistance of the synthesized ceramics were investigated. By the impedance spectroscopy method, a system Ce0.8Y0.2O2-? obtained by the sol gel method was found to have the highest electrical conductivity reaching 5.37 mS/cm at a temperature of 550 ?С and the lowest activation energy equal to 0.83 eV in the temperature range of 300 – 550 ?C. The contribution to the conductivity of the grains and the grain boundaries is defined. A common conductivity is shown to be decreased because of the resistance of the grain boundaries for all samples.
A complex of physico-chemical studies was carried out: X-ray phase analysis, differential thermal analysis, chemical analysis of vanadium production waste. It has been established that these wastes containing 17.39 % Mn2O3 in their composition are promising raw materials for the production of volumetric wall ceramics. The effect of heat treatment at 200, 500, 600 and 700 ?C on the phase composition of vanadium production waste has been studied.
The effect of thermal plasma energy on the morphology and phase composition of agglomerated refractory oxide powders has been studied. It has been established that during the processing of an agglomerated powder based on the ash residue of a state district power station in a thermal plasma flow with different thermophysical characteristics of the carrier medium, three types of morphological features of the particles are formed: a dense particle with separate gas inclusions in the surface layer; hollow spherical particle; vitrified agglomerated particle with solid-phase inclusions. Agglomerated polycrystalline powders after processing according to XRD data are amorphous. The X-ray diffraction patterns of particles processed in the turbulent regime of plasma jet outflow show a small Bragg peak of ?-quartz. This means that the grains do not reach the molten state in the center of the agglomerate.
As part of the study, an assessment was made of the possibility of using magnesium-containing waste from the production of periclase in the processes of engineering environmental protection. Evaluation of the efficiency of removal of phosphate and ammonium ions using powdered brucite, water-soluble magnesium salts and complex titanium-containing coagulants has been carried out. The high efficiency of magnesium-containing reagents in the processes of co-precipitation of sparingly soluble magnesium ammonium phosphate and in the processes of wastewater treatment with a high pH value has been proven. The approbation of magnesium-containing reagents was carried out on waste waters of plastic processing and cement production.
Two-stage method of hollow channels formation inside glass by direct laser writing and selective etching is perspective way for microfluidics devices manufacturing. In this work the influence of the etching solution concentration and laser writing conditions (the laser beam scanning speed, pulse energy) on the etching rate, selectivity and roughness of hollow channels in quartz glass is studied. The use of 1M NaOH makes it possible to increase the etching rate of hollow channels up to 300 µm/h while maintaining high selectivity up to 680.
An experimental study of the thermal conductivity coefficient of glass coatings of pipes has been carried out. A device for experimental study of the thermal conductivity of the glass-coating of the pipe has been developed. To a greater extent than the composition, the thermal conductivity of glass depends on the temperature. It has been established that the thermal conductivity of the glass coating increases by several tenths of a watt with an increase in temperature up to 600 ?C. Studies have shown that an increase in the temperature of a glass coating leads to a slight improvement in its thermal conductivity. The highest thermal conductivity is possessed by a coating made of glass of the S-89 and S-52-1 brands. These grades of glass are recommended for pipelines operating at elevated temperatures of heat transfer fluids.
The results of studies of chemical, X-ray phase, microscopic, electron microscopic and granulometric analyzes, as well as physical and mechanical properties of quartz sand from of the Tamdi deposit are presented. It has been established that this quartz sand can be used as a promising source of high-quality raw materials for the production of glass and glass-ceramic materials for technical, household and construction purposes in the conditions of Uzbekistan.
The influence of the concentration of decorated carbon nanotubes and the influence of the concentration of eutectic additives, as well as the effect of the firing regime on the strength characteristics of the structural ceramic material were considered. During the investigation, it was found that the best properties have samples with a four-component additive introduced in an amount of 6 wt. %. The optimum concentration of carbon nanotubes was 1.5 wt. %.
Wollastonite ceramics was obtained from chalk and diatomite by the method of solid-phase synthesis of components. The influence of charge composition, modes of its mechanochemical activation and temperature-time modes of heat treatment on the phase composition, physical-mechanical and thermophysical properties of ceramic materials is studied. As a result of the joint mechanochemical activation of the charge components (chalk + diatomite), the temperature of the solid-phase synthesis of wollastonite ceramics was reduced to 900 °C. After firing for 2 hours, ceramic samples were obtained almost 90 % consisting of the mineral wollastonite. The compressive strength of the samples is 22 – 23 MPa at an average density of 1270 – 1300 kg/m3. The material has a stable thermal coefficient of linear expansion (TCLE) under 7.76?10–6 K–1. It can be operated at temperatures up to 1100 °C inclusively. Thermal insulation samples with an average density of 435 kg/m3, compressive strength of 2.2 MPa, thermal conductivity of 0.099 W/(m °C) and the limiting operating temperature under 1050 °C were obtained from the prepared charge mixture and foamed perlite. The resulting materials can be used as thermal insulation for industrial and civil facilities, refractory insulation of industrial furnaces, equipment, etc.
It was shown that the use of liquid-phase foaming agents is promising for the synthesis of foam glass. The dynamics of the change in the glass particles size in the process of batch obtaining was studied. It was shown that additional grinding of glass powder particles occurs during the mixing process. The influence of the time of the batch mixing on the structure of the foam glass was investigated. It was shown that the density of the obtained foam glass is directly proportional to the batch mixing duration. Changes in the structure of the material associated with the processes of distribution of a liquid foaming mixture on glass powder particles during mixing and subsequent changes in the dynamics of the glycerol thermal destruction processes were described.
