The corrosive effect of the slag-forming mixture (SFM) of a crystallizer on monoclinic zirconium dioxide partially stabilized by calcium oxide or yttrium oxide was studied. It was experimentally established that zirconium dioxide stabilized with yttrium oxide had better corrosion resistance due to the low decomposition rate of the stable phase ZrO2–Y2O3 when exposed to SFM of the same composition.

The possibility of laser cutting plasma-sprayed refractory products made of aluminum oxide is investigated. An industrial laser complex KS-5VDM1-3 Navigator (VNITEP, Russia), equipped with an LS-3 ytterbium fiber laser with a power of 3 kW, is used in order to develop cutting conditions. It is established that immediately after completion of the plasma spraying process, article material phase composition is a collection of various modifications of aluminum oxide, and subsequent material heating leads to a series of polymorphic transformations accompanied by changes in item material volume and density. The process is complete when all aluminum oxide polymorphic modifications are transferred into the only stable phase α-Al2O3 (corundum). It is shown that laser cutting of plasma-sprayed aluminum oxide products is only possible when transition of all its phase modifications to corundum is completed. In the opposite case, a sharp change in product material volume, due to polymorphic transformations occurring under conditions of a high temperature gradient that occurs during laser cutting, leads to product destruction. A plasma-sprayed article, whose material is entirely the α-modification of aluminum oxide (corundum), withstands high temperature gradients and is easily laser cut without destruction. Cutting technology of plasma-sprayed refractory products made of aluminum oxide is assimilated at the Scientific and Educational Center for the Implementation of Laser Technologies at Vladimir State University.

To capture pollutants in various buildings and structures, it is necessary to use local exhaust systems. One of the criteria of the local exhaust efficiency, the pollutants capture rate, is proposed to be increased due to the impact of a swirling annular jet and the occurrence of a reverse air flow. The circular exhaust is placed coaxially into the external cylindrical casing, in which the air flow is swirled due to the tangential supply of two supply jets into the casing. A vortex dome, which helps to increase the efficiency of such a vortex exhaust, is formed. The change in the axial air velocity with distance from the vortex exhaust was experimentally and numerically investigated for 11 structures, in each of which 4 different ratios of exhaust and supply air flow rates were set. In the investigated options of using the proposed exhaust systems, the velocity increases significantly at a certain range of distances from them. Acombination of design and operation mode parameters that contribute to the highest capture rate by vortex exhaust is determined. The results obtained are useful in designing effective exhaust systems to capture pollutants.

Results of studies of Al2O3 suspensions made with different CaO and SrO contents are presented. The pH level increased with an increase in the content of CaO and SrO in the Al2O3 suspensions. The dynamic viscosity of the Al2O3 suspensions grew exponentially as the CaO content increased from 0.45 to 2.25 mol% and SrO, from 0.42 to 2.14 mol%. Reflections of CaAl12O19 and SrAl12O19 were observed in sintered materials of suspensions to which CaO and SrO, respectively, were introduced. These compounds had a lamellar structure.

Acid-resistant products with high physical, mechanical, and chemical parameters for firing temperatures in the range 1250 – 1300°C were obtained using slag from the smelting of carbon-free ferrochrome with increased contents of refractory oxides (Al2O3, 57.8 wt.%, CaO 14.9 wt.%, MgO 12.7 wt.%, and Cr2O3 5.6 wt.%) in the production of acid-resistant materials based on non-enriched kaolin clay. The introduction of slag from the smelting of carbon-free ferrochrome into the ceramic compositions contributes to the formation of highly refractory minerals (corundum, chromium oxide, bonite, mayenite, magnesium spinel), increases the mullite content, and reduces the open porosity, thereby strengthening the product.

The influence of the shape and dimensions of the chimney blocks on regenerative heat transfer in a glass-making furnace with a horseshoe-shaped flame is considered. Chimney blocks with various combinations of the cross-section area, height, and wall thickness have been studied. To evaluate the efficiency of the blocks, the regenerator design parameters were used. It has been established that the smallest volume and weight of the high-temperature zone of the packing, limited by a flue gas temperature of 1100°C, can be achieved by using TL 15/15 blocks, characterized by a specific volume of 0.259 m3/m3 and a specific heating surface of 18.9 m2/m3. In the sulfate condensation zone and the low-temperature zone of the packing, TG 15/15 blocks should be used, for which the specific volume and specific heating surface are 0.296 m3/m3 and 17.4 m2/m3, respectively.

The possibility of solving the problem of achieving uniform distribution in a ceramic charge based on silicon nitride of a small amount of oxide sintering additives using an ideal mixing model is considered. The mixing power necessary to prevent the separation of the mixture and obtain a homogeneous suspension during solvent removal is calculated based on a determination of the complex viscosity and the free deposition rate of silicon nitride particles in a mixture with organoyttroxanealumoxane (OYA) solution. The coefficient of heterogeneity (variation) calculated according to the analytical results confirmed that aluminum and yttrium oxides were uniformly distributed in the silicon nitride-OYA charge obtained as a result of implementing the ideal mixing model.

A methodological approach is developed ensuring operational stability of ceramic tools based on creating a functional surface layer on weakly defective sintered ceramic after removing a defective surface layer formed after grinding. Advantages of a functional surface layer created on ceramic tools are confirmed as a result of tests.

Optimum chemical, charge, and fractional compositions of dinas ramming mixes for lining heating units are developed. It is established that the best results, in terms of material composition and thermomechanical properties, are exhibited by test specimens based on quartzite, with a quartz sand and kaolin content not more than 20 wt.%. Possibilities are demonstrated for partial replacement of quartzite with quartz sand in developing new dinas ramming mix compositions.

A novel technology is proposed for the production of superdense aluminosilicate refractories with increased slag resistance for thermal disposal of fluorine-containing carbonaceous wastes, based on the aluminosilicate raw materials of the Republic of Kazakhstan. The use of “ceramic” technology provides a structure with water absorption below 1% in both chamotte and refractory products with different Al2O3 contents.

Chemical aspects of reduction of natural topaz Al2SiO4[F1,3(OH)0,7] are studied. It is shown that with a weight ratio of Al:topaz = 0.24 corundum synthesis is completed in one stage (780 – 1200°C) without formation of intermediate mullite. Production parameters of topaz aluminothermal processing are selected that make it possible to convert up to 84% of aluminum from a charge into fused corundum with 98.6 wt.% Al2O3 and up to 24% of silicon into high-purity product.

Entropy is a key notion in the analysis of properties of mass systems. This notion was first formulated in thermodynamics and then expanded to gas systems. In the previous paper, the author has formulated the notion of entropy for two-phase flows. The analysis of properties of this kind of entropy made it possible to formulate the conditions of invariance of the behavior of narrow-size-class particles in a two-phase flow. In addition, this analysis has revealed a universal dimensionless parameter of affinization of separation curves, which makes it possible to control the process of bulk materials separation into fractions by particle sizes and densities. The use of this parameter will enable solving a number of challenging problems related to specific technological processes.

Sintered blanks for spherical rolling bodies of silicon nitride ceramics were obtained by addition of an yttrium-containing organoalumoxane, i.e., an organoelement oligomer, that was soluble in traditional organic solvents and converted during pyrolysis into an aluminum-yttrium oxide sintering additive with a given mass ratio Al2O3/Y2O3 = 3/1. Studies conducted using thermogravimetry, x-ray phase analysis, and optical and scanning electron microscopy showed that features of the use of the elementoxane instead of aluminum- and yttrium-oxide sintering additives were a uniform distribution of aluminum and yttrium oxides in Si3N4 ceramics and the chemical activity of the pyrolysis products of organoyttriumoxanealumoxane (OYA), including amorphous nanoscale oxides on the surface of the Si3N4 powder. The density, porosity, microstructure, and degree of purity of the polished surface of the obtained ceramic indicated it was promising for use as a blank for high-quality rolling bodies.

Properties of diatomite from the Il’yinsk deposit (Sverdlovsk region) and the effect of orthophosphoric acid (OPA) on it are studied. It is established that in the OPA-diatomite system on firing at 1400°C with an increase in OPA concentration in an aqueous solution the cristobalite content reaches 70 – 71%. Diatomite samples formed in an aqueous solution of OPA do not break down or melt at a heating temperature of 1400°C, while specimens without OPA begin to melt on heating above 900°C.

A complex titanium-silicon carbide of the Ti3SiC2 composition was synthesized using various starting components in a high-temperature furnace at 1400°C for 1 h and by subsequent hot pressing at a temperature of 1350°C and a pressure of 30 MPa for 15 min. The content of Ti3SiC2 was calculated by the Rietveld method, with the Ti:Si:TiC ratio reaching 1:1.2:1.8 98.6 vol.% after hot pressing. The microstructure and phase composition of hot-pressed materials, as well as the physical and mechanical characteristics of sintered and hot-pressed Ti3SiC2-based materials, were studied.

Dense materials based on Si3N4 with oxide additives activating sintering were obtained by reaction and liquid-phase sintering and hot pressing. Their physical and mechanical properties were determined. Porous samples were obtained by semi-dry forming of Si3N4 + Si workpieces followed by reactive sintering in a nitrogen atmosphere. The porosity was controlled by decreasing the Si concentration in the initial charge. The thermal conductivity of the materials was highly dependent on porosity and decreased with increasing temperature. The thermal conductivity of hot-pressed materials decreased from 60 W/(m·K) at room temperature to 35 W/(m·K) at 1200°C, at which temperature the weight gain of the samples was 7 × 10–4 kg/m2. The weight gain of the porous materials increased from 4 × 10–3 kg/m2 with a sample porosity of 32% to 6 × 10–3 kg/m2 with 56% porosity. It was shown that an oxygen impurity was the main reason for the decrease in the thermal conductivity of the Si3N4 ceramics.

The main methods of moisture protection of products made of quartz ceramics are described. The advantage of quartz ceramics modified by bulk impregnation with MFSS-8 solution is shown. Experimental data on the properties of modified quartz ceramics obtained with different types of impregnation are presented.

X-ray phase analysis, IR spectroscopy, and scanning electron microscopy were used to study compositions of expanded vermiculite (phlogopite) – kaolinite clay – liquid glass and their transformations in low-temperature (25 – 500°C) and high-temperature regions (1020°C). Phlogopite underwent a complex transformation up to the appearance of olivine and spinel phases and destruction of the kaolinite lattice. It was established that heat treatment at 500°C was necessary to make the composition resistant to atmospheric effects (water and CO2) and to achieve the optimal combination of basic physical and technical properties.

This study investigated refractory materials produced by DINUR for constructing the roof of a new melter EP-6. The acid resistance of materials under the influence of nitric acid vapor and nitric acid solution was determined. According to the research results, mullite–silica concrete-grade MKRV-53 was recognized as the optimal material for constructing the melter roof.

This research analyzes the methods for producing silicon nitride and the properties of initial powders. The main methods for obtaining materials based on silicon nitride are described. Liquid-phase sintering and hot pressing were used to develop dense materials based on silicon nitride. As a sintering additive, 3 – 10 wt.% and 5 – 20 wt.% of yttrium-aluminum garnet were used for hot-pressed and sintered materials, respectively. The mechanical properties (modulus of elasticity, bending strength, fracture resistance, and Vickers hardness) of sintered and hot-pressed materials have been studied. Maximum properties were obtained with sintered materials containing 15% oxides and hot-pressed materials containing 10% oxides.