The formation of ceramics based on Bi1–xSrxFeO3–δ solid solutions produced by glycine-nitrate combustion was studied. The yield of target product was greatest for x = 0 – 0.5. The synthesis temperature range and start of grain sintering correlated with fusion of the surface phase. The sintering activation temperatures and thermal-expansion coefficients of the nanocrystalline ceramics were determined

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The general nature of the dependence of engineering and service characteristics of refractory concretes with an average cement content, and also low-cement (LCRC), ultra-low cement (ULCRC) and cement-free (CFRC), on the content of CaO (or HAC) in them is analyzed. Significant advantages of cement-free concretes are the reduced moisture content of the concrete mixture, which determines their increased

We propose an engineering solution of a screen with elevated efficiency of separation of clay rock masses. The most rational design of undriven bar screens (namely, cantilever and spring-loaded screens) is determined. We present a mathematical model and a procedure for the evaluation of the parameters of screens. It is shown that, in the case of selection of the proper parameters for the grates of

The effect of the formation of sintered TiC–ZrC solid solutions in mullite–WC–TiC–ZrC and mullite– c-BN–TiC–ZrC samples during spark plasma sintering of compositions at a compression load of 60 MPa in the range of 1200–1600°C on their phase composition, microstructure, relative density, open porosity, linear shrinkage, physicomechanical properties, and linear correlation of elastic modulus and fracture

An explanation of the physical nature of the experimentally determined concentration dependences of the electrical conductivity of ceramic composite materials of the SiC–TiN (ZrN) system is proposed. A model of the structure and a method for calculating the electrical conductivity of composite materials, as well as experimental dependences of the electrical conductivity of sintered ceramics of the

We discuss the problem of determining optimum thicknesses for the refractory and thermal insulation layers to minimize the total cost of the lining and the fuel used to compensate for thermal losses. The proposed methodology (with the required temperature at the boundary of the lining layers specified as an additional condition) reduces the 2D constrained optimization problem for a cost function with

The effect of ultrasonication time after hydrothermal synthesis of hydroxyapatite (HA) using the precursor system Ca(NO3)2–(NH4)2HPO4–NH4OH on the phase composition and degree of crystallinity was examined. HA samples were studied using x-ray diffraction and FT-IR spectroscopy. The studies showed that ultrasonication regardless of the duration had no effect on the phase composition and degree of crystallinity

The paper presents experimental results of producing refractory electrically conductive TiC + xC composites by SHS pressing method. The conditions for obtaining composites with residual porosity of about 20% were established. The effect of the composition of the reaction mixture on phase content, microstructure, compressive and bending strength, as well as electrical resistivity of SHS composites was

The properties and wear resistance of induction furnace linings made from Karelian vein quartz during the smelting of copper-based alloys are studied. The wear mechanism of a vein quartz lining is demonstrated.

AA7075-xZrB2 (x = 0, 5, 10, 15, and 20 wt.%) composites were manufactured by reacting potassium zirconium fluoride (K2ZrF6) and potassium tetrafluoroborate (KBF4) with molten AA7075 at 800°C. The ZrB2 particles formed by the reaction were fairly uniformly distributed throughout the whole composite. The microhardness of the composites increased from 45 to 78 VHN with ZrB2 contents from 0 to 20 wt.%

The main rheological and processing properties of individual and mixed binders based on SiC and Si are studied. Phase and chemical compositions, main physicomechanical characteristics, and microstructures of samples after annealing in N2 are investigated.

An experimental assessment of the reliability of a mathematical model and software for calculating the phase composition of steelmaking slags is given. It is established that the model proposed and the software developed may be used during modification of the slag chemical composition after furnace treatment of steel to reduce slag corrosion of a metallurgical unit lining and to suppress the effect

Features of impregnation a corrosive medium for the working layer of the lining of rotary kilns and casting ladles for ferroalloy production are considered, and results are provided for analysis of the impregnation thickness. The change in the thermal conductivity of refractories after service is investigated on the basis of a developed and patented method. It is found that the thermal conductivity

The paper discusses the technology for producing bulk lightweight spherosilicate materials as an alternative to expanded vermiculite-based thermal insulation products. The technology is based on the idea of using granulated expanded polystyrene to create a core of silicate spheres coated with special liquid glass-based mixture and treated with carbon dioxide in the process of forming polystyrene-silicate

The effect of pumping a mixture of methane and hydrogen in a UHF-discharge through layers of diamond powder on sediment structure formation during chemical infiltration from the gas phase is studied. It is established that diamond growth in a gas phase proceeds at the surface of the first layer and does not depend on diamond powder size; starting from the second layer diamond growth from the gas phase

Optimum production regimes are established for steel extra-furnace treatment providing not only low contamination with non-metallic inclusions (NI), but also formation of NI with favorable morphology not having a deleterious effect on steel corrosion resistance. It is shown that this is achieved by controlled input of Al in steel alloying and deoxidation stages, limiting its content in steel, limiting

We study the character of phase formation and the properties of aluminosilicate lightweight materials produced from the raw materials of the Angren and Samarkand deposits in Uzbekistan. We determine the phase composition, microstructure, physical, and technical properties of compositions with admixtures of plastic black clay and burning additives in the form of coke of various fractional compositions

Refractory clay and water in a confined space are in a force field arising from the active swelling of a plant-based starch-containing additive. During self-compaction shrinkage moisture is absorbed by the plant additive and squeezed into clay particles. It has been established that the production properties of the additive are affected by starch mineralogical, chemical, thermodynamic and structural

Results of studying the rheotechnological properties of moldable refractory mixes based on bauxite suspensions plasticized with refractory clay are presented. Features of the effect of filler diameter and binder content in a mix on structural-mechanical and operating properties of specimens based upon it are established. Specimens from the developed mixes intended for molding at low pressure (up to

Technological conditions for preparing ceramics based on MoSi2 hardened by SiC and ZrB2 that have enhanced physicomechanical properties (relative density ≥99.1%, bending strength 480 MPa) were experimentally investigated. The developed composites could be recommended for the creation based on them of functional structural ceramics operating at elevated temperatures in an oxidizing environment.

A porous catalytically active membrane based on α-Al2O3 has been synthesized. For the synthesis of the membrane, powdered additives of the eutectic composition of magnesium oxide and silicon carbide were introduced into the initial Al2O3 powder using compression at pressures of 30 to 90 MPa and sintering at 1350°C. To impart catalytic properties to the synthesized membrane, up to 10% Fe2O3–Cr2O3 was

Characteristics of domestic corundum insulation objects are given. The properties of corundum lightweight objects obtained from microporous calcined alumina are studied. It is shown that product physicochemical properties are no worse than traditional lightweight objects of corundum composition.

A sharp reduction in the ultimate shear stress in the range of 20 – 80°C is observed during preparation of specimens of a clay component without thinners that facilitates development of cracks and defects. Use of pyrophyllite in ceramic mixes during specimen preparation provides a gradual reduction in the ultimate shear stress Pm in the range of 20 – 80°C. It is shown that in order to improve specimen

We consider various types of design of the refractory equipment for the chambers of tundish ladles of continuous casting machines (CCM). The improvement of the equipment guarantees the efficient formation of metal flows and creates conditions for the improvement of its quality. We estimate the serviceability of partitions and baffles existing for the tundish ladles of CCM: their strength, the absence

The paper presents an experimental study of the effect that preliminary synthesis by iodine transport of ceramic powders with a core-shell structure has on apparent density, open porosity, elastic modulus, and sound propagation velocity of corundum ceramics sintered at various temperatures.

We present the results of investigation of the regularities of sintering and properties of corundum ceramics based on alumina with admixtures of ultradispersed powder of Al2O3(Al2O3 UDP) synthesized by the electrochemical method. It is shown that, as the firting temperature and the concentration of Al2O3 UDP increases, we observe a regular elevation of the linear shrinkage, microhardness, and ultimate

It is proposed to modify the method of preparing self-consolidating mixes by changing the nature of the compacting component, i.e., from expensive and environmentally unsafe polystyrene to a burnable plant-based additive that can self-absorb shrinkage moisture from molding material enclosed within a hydraulically closed volume. At the same time, part of the mixing water under pressure penetrates into

Results are provided for a study of diatomite of the Il’insk field (Sverdlovsk region) for preparation of unmolded insulation materials and their use as heat insulating materials in crucibles with molten aluminum. Use of diatomite as a heat insulating material makes it possible to reduce power consumption during holding molten aluminum in the resistance furnace crucible, prevents development of hydrogen

The technology for synthesizing TiN, ZrN, and HfN involves combustion in air of mixtures of aluminum nanopowder (NPAl) and the corresponding dioxides and contradicts thermodynamic calculations. Nitrides should be oxidized in the presence of air and converted to the oxides. The synthesis of nitrides in air is a new direction in the technology of refractory nitrides. Nitrogen from air is used in the

We study the influence of composition and technological conditions on the synthesis of cordierite ceramics from raw materials with origin in the Russian Federation. The structure, porosity, density, and basic thermomechanical properties of cordierite ceramics are investigated with the use of the x-ray phase diffraction and petrographic analyses. Under the industrial conditions, we produced a material

A heating of a carbon-made product and thermophysical properties of a carbon material in the temperature range from 300 to 2,500 K were studied. A discrete-heterogeneous mechanism of heating the surface of a multi-dimensionally reinforced carbon-carbon composite material (CCCM) subject to accelerated heating was revealed. Based on the results of testing carbon materials in the temperature range from

The article presents an analytical review of publications on oxide ceramic binders that are used to prepare porous silicon carbide materials. The most promising ceramic binders are determined and the properties of materials based on ceramic binder data are provided. Mechanisms of modifier action making it possible to reduce the heat treatment temperature by up to 100°C are considered.

Eutectic LaB6–ZrB2 powder was synthesized by borothermal reduction of an La(OH)3–ZrO(OH)2 mixture under vacuum with isothermal curing at 1200 – 1600°C. The mixture of hydroxides was prepared via coprecipitation from aqueous solutions of La and Zr nitrates in a suspension of amorphous boron. The effect of an excess of B on the phase and elemental compositions of the boride mixture was studied. The particle

The analysis of literature data on the technological principles of controlling the formation of non-metallic inclusions in carbon and low alloy steels to increase their corrosion resistance in aqueous media is carried out. The key technological parameters of steel treatment in the ladle are summarized that ensure not only low contamination of steel with non-metallic inclusions, but also the formation

The main production defects typical for ceramic-matrix composites (CMC) with an SiC matrix prepared by liquid-phase siliciding are formulated: bulk and surface CMC cementation, nonuniformity of the siliciding process, degradation of carbon and SiC fibers due to molten Si, the presence of microcracks, open and closed pores, and internal cracking and swelling of the final CMC. Reasons for their occurrence

The analysis of a heat transfer mechanism in the bulk of carbon-carbon composite materials was performed. It was experimentally determined that a homogeneous thermal condition is established at a depth of up to twenty structural cells of the composite. A characteristic layered porosity structure of the material formed by crack-like pores was revealed, and the extent of reduction in thermal conductivity

The effects of iron-containing compounds on Si2N2O production during burning in N2 of an Si + SiO2 mixture were studied. It was established that the phase composition and morphology of the crystalline combustion products depended on the iron-containing compound. Si2N2O powder without impurity phases was obtained in the presence of FeCl3·6H2O and formed polycrystalline fibers consisting of ultrafine