Том 58, № 6 (2018)

We perform physical and mathematical modeling of tundish hydrodynamic processes in the 4-strand continuous bloom casting machine at the EVRAZWest Siberian Metallurgical Complex. Aphysical model of the tundish is used for qualitative assessment of melt mixing processes. A qualitative assessment of nonmetallic inclusion removal efficiency in the tundish is provided for models that employ refractory components in a variety of different configurations. We develop recommended design parameters for full-height refractory dividers in the tundish.

Information is summarized and results are provided for comprehensive study of ferrochrome aluminothermal slags carried out over several decades by both home specialists and the authors of the article. Experience is reflected for application and prospective areas are considered for utilization of ferrochrome slag.

We developed a technology of manufacturing refractory products from pure oxides with getter titanium coatings intended for the fusion and pouring of chemically active metals and alloys. This technology is realized by the method of plasma spraying. The obtained products guarantee the reliable protection of the melts located inside them against the penetration of gases from the atmosphere. The application of these products significantly increases the reliability of the process of growth of parasite-free single crystals from magnetically hard alloys of the Fe–Co–Ni–Cu–Al–Ti system and makes it insensitive to the presence of gaseous admixtures of nitrogen and carbon and water vapors in the inert atmosphere of growth chamber.

Results are provided for development of mullite-corundum materials based on refractory filler (mullite or corundum) and a high-alumina ceramic binder (acicular mullite and fine-grained corundum). A model is presented and implemented for a structure of fragmentary type of mullite-corundum material providing good refractory qualities.

We present the results of investigations of the process of sintering and the changes in the properties of corundum ceramics depending on the content and type of introduced highly dispersed Al₂O₃. The specimens are produced by the slip casting and sintered at various temperatures. It is shown that, for the other identical conditions, it is reasonable to use highly dispersed powders with spherical particles with an aim to improve the physicomechanical properties of corundum ceramics. In the production of dense ceramics, the shape of particles of highly dispersed powders does not have any significant influence on the decrease in the temperature of sintering.

The possibility of utilizing the porosity of coatings produced by micro-arc oxidation (MAO) to create ceramic-metal coatings is investigated. It is shown that ceramic-metal coatings can be produced by electrochemical deposition of nickel on MAO-coatings. Taking advantage of the features of low-temperature heterophase transfer, microarc oxidation, and electrochemical deposition of nickel, functionally graded ceramic-metal coatings were produced on steel surfaces, which are promising for operation in friction contact nodes of machine systems.

We present some results of investigations of the influence of various factors on the improvement of operating characteristics of refractory concrete. We describe the procedures of laboratory tests and their results in the investigation of the influence of different additives and moisture content on the properties of refractory concrete.

The effect of firing temperature in the range 800 – 1640°C on the change in phase composition, structure, and some properties of specimen materials prepared on the basis of composite composition HCBS is studied. Four temperature ranges are stablished by a dilatometric method with a nonisothermal heating rate of 300°C/h corresponding to normal thermal expansion (up to 800°C), sintering accompanied by shrinkage (800 – 1150°C), mullitization accompanied by growth (1150 – 1400°), and sintering of mullitized material (1400 – 1500°C). A set of methods is used (XPA, dilatometric analysis, optical, and electron microscopy) to specify the phase composition and material structure in the firing temperature ranges noted. After firing at 1400 – 1640°C the material contains 38 – 42% mullite, 50 – 55% corundum, and balance glass phase and titanium compounds.

Phase formation was regarded during the reactive sintering of boron carbide materials in the presence of silicon or aluminum, or silicon-aluminum melts. The inter-phase interaction was investigated, the melting (decomposition) temperatures as well as crystallographic data on the phases in the regarded systems were considered. Methods for reducing the content of Si and Al₄C₃ in the composition of the reactive-sintered material were discussed as these substances negatively affect the physical and chemical properties of the material.

The possibility of producing optically transparent ceramics from magnesium aluminate spinel (MAS) is considered. The conditions of preparing the precursor powder and the MAS powder were investigated along with the effect of synthesis temperature and gallium oxide additive on the properties of the powder.

From the viewpoint of materials science, we analyze the development of heat-resistant vibration- and shock-proof electrotechnical materials (products), including electric insulators operating in the machines for automatic welding of bimetallic tubular elements. We propose materials and technological decisions for the creation of electric insulators of different engineering applications.