Vol 60, No 2 (2019)

Features are considered for working conditions of slab CBCM tundishes on the example of the 27-ton unit of the oxygen-converter workshop of PAO Severstal’. Results are provided for mathematical modeling of hydrodynamics in a tundish with different turbulence dampers for the inlet stream. The designed, patented, and implemented metal receiver (brand REINSTREAM^®) with a wavy inner surface is intended to improve continuously-cast billet quality, as well as providing increased stability and productivity due to the special design.

We have studied flame guncreting and the guncrete mortars used in ferrous metallurgy, as well as the use of flame guncreting to make repairs to linings without shutting down equipment, thereby improving the lining resistance of equipment used in non-ferrous metallurgy. A special guncreting mortar targeted to the specific operating conditions for these equipment linings was developed. It was found that a low-melting-point component or thermite mixture used for self-propagating high-temperature synthesis (SHS) can be added to the guncrete mortar to reduce the temperature. A guncrete machine was designed to handle this guncrete mortar. Testing of the new guncrete machines and guncrete mortars at non-ferrous metallurgy facilities showed a factor of 1.8 – 2.5 increase in the wear resistance of the linings.

A transparent submicron-grain sized cubic yttria-stabilized ZrO₂ ceramics was obtained by spark plasma sintering in the temperature range from 1200 to 1400°C at a relatively low pre-pressing pressure (100 MPa). The produced ceramic samples have demonstrated high light transmission in the visible and near-infrared spectral regions. The paper presents elastoplastic properties and microstructure of the ceramics and discusses the relationship between the optical and elastoplastic characteristics, as well as microstructure.

The results of studies of the structure, phase composition and specific surface area of powders based on zirconium dioxide obtained by the method of thermal decomposition of a mechanical mixture of hydroxide and a stabilizing additive are presented. The forming and sintering of ceramic samples obtained from calcined powders were studied, as well as some properties of the ceramics. It has been shown that fine-grained dense high-strength ceramics with a flexural strength of 860 MPa and microhardness up to 12 – 13 GPa can be obtained from the synthesized powders.

The results of studies of the reduction of alkali metal oxides in nepheline sludge are presented. The alkali-containing phase is sodium hydroaluminosilicate. The methodology of the experimental studies involved the preparation of a water suspension with a given W:S ratio, mechanical stirring, heating, aging and separation of the pulp on a vacuum filter. Atechnology has been developed capable of reducing the alkali content by 21% of the initial amount of alkali, which has increased the melting temperature by 310°C. Based on the obtained results, pilot plant was designed and refractory heat-insulating materials were developed where the expensive mineral raw materials are substituted with non-scarce man-made waste.

This review provides the analysis of aluminum oxide, including the properties associated with its use, types of commercial products, production methods allowing for manufacturing aluminum oxide in dispersed state, in the form of polycrystalline ceramics and single-crystal products, as well as chemical aspects of the technological processes. Part 3 of the review provides information about Russian manufacturers of alumina ceramics mainly in the densified technical form), refractory materials, and dispersed alumina, as well as contains data related to composition and properties of the products, and a brief list of product lines. In addition, there is information about small businesses and organizations engaged in innovation and commercialization of the modern alumina ceramics.

An effective method for preparing dense granular ceramic from SiC with a residual porosity of less than 5.0% is the use of additives of oxide system eutectic compositions. The effect of fine eutectic powder in the Al₂O₃–MnO–SiO₂ system depending on the composition of the charge, compaction pressure and firing temperature on the sintering performance of granular SiC ceramics, is considered. It is established that after firing ceramic at 1250°C with 15 wt.% of eutectic additive, its porosity is 4.2%, and the ultimate strength in bending reaches (95±5) MPa.

Research results show that it is possible to obtain high-quality lightweight refractories based on industrial waste (the clay part of the gravity tailings of zircon-ilmenite ores, non-ferrous metallurgy waste. and drilling slurry from oil production) without using traditional natural materials.

We present the results of the experimental investigations of the phase and structure formation in a layered ceramic material based on the MAX phase in the Ti/Ti–Al–C system obtained under the conditions of combination of combustion processes with high-temperature shear deformation (SHS compaction). We analyze the specific structural features of the developed material and the character of interaction between the products of synthesis and the surface layer of titanium substrate.

We study the inhomogeneity of stresses on the boundaries of the main structural elements of Al₂O₃-ceramics under the conditions of unsteady thermoelasticity, which are of especial importance for the development of recommendations concerning the choice of ceramics for the end ceramic cutters.

Sources of powdered waste in processing clay and other ceramic raw materials for crushing and screening complexes are crushers, screens, and transfer units. A new structural solution for a fixed bar grizzly is proposed providing a reduction in energy consumption for ventilation. The area of the screening surface, linear dimensions of the grate for its required productivity, and also strength calculations for the grate cross section and assemblies for attaching them to the beams, are determined

The effect of prolonged heat treatment (single- and two-stage firing in a tunnel kiln) of specimens based on HCBS in the Al₂O₃–SiO₂ –SiC system on their indices is studied. Specimens containing 15% SiC and 1 and 2% Si are characterized by a significant increase (up to 9%) in porosity and a reduction in strength compared with original specimens (without SiC) after prolonged heat treatment (120 hours in the range 1300 – 1400°C). significant increase in specimen volume is due not only to oxidation of SiC or Si, but also due to additional mullite formation. It is assumed that subsequently during oxidation of SiC at a certain stage of heat treatment there is mullitization due to the interaction of newly formed SiO₂ in the form of cristobalite with bauxite Al₂O₃.

We study a dust-air flow near a vertical rotating cylinder with suction unit placed on the lateral surface. On the basis of the developed computer model of this suction unit, we determine the influence of the disks mounted on the cylindrical surface on the intake air flow and on the capture of dust particles by the suction unit. We also determine the design and operating parameters of the proposed disk cylindrical suction unit promoting the decrease in the dust loss. The influence of the size of disks, their number, and the aspirated air flow on the dust removal is established. The proposed design of a rotating disk cylinder suction unit can be used in the aspiration shelters equipped with the function of dust-collecting chamber.