Russian Metallurgy (Metally)最新文献

The influence of a deposition technology on the structure and properties of a ceramic coating on a turbine blade is studied. The proposed technical solution of satellite rotation of a blade relative to a vapor flow is found to increase the uniformity of the coating thickness and to form a thermal barrier layer on the turbine blade platform. The microstructure of the thermal barrier coating layer around the perimeter of the blade airfoil is investigated.

A domestic 100-t electric arc furnace (EAF) is used as an example to study the boundaries of asymmetry of the inductive reactance of the furnace circuit that can occur during operation, specifically, during untimely electrode slipping. The designs of current conductors in coplanar and triangulated configurations with current-conducting arms and tube buses along the arms of electrode holders are considered. Triangulation is shown to decrease both the design and operational asymmetry of the short network in any design of the rigid moving part of the current conductor.

To increase the strength of a welded joint during electric contact welding of a filler tape, we propose to preliminarily form a helical structural element of trapezoidal cross section on the surface of the shaft to be restored. The plane problem of plastic deformation of such an element is analytically solved. The relative deformations over the cross section of the element are determined. The obtained results can be used for the restoration of worn shafts by contact welding of tapes made of alloyed and heat-resistant steels.

This study aims to fabricate Cu–Mo electrocomposites using an acidic sulfate bath. The primary objective is to ensure a uniform distribution of molybdenum inclusions throughout the copper matrix, which is required to achieve maximum microhardness. Copper-based composite coatings with molybdenum powder incorporated into a galvanic matrix are produced. The particle size of the dispersed phase is chosen to achieve a 19.15% filler concentration. The resulting coatings are characterized by a significantly higher microhardness, measuring 58% greater than that of standard galvanic copper coatings.

The carbothermic production of a titanium-containing ferroalloy is subjected to thermodynamic modeling. The Ti–Al–Si–Fe–C–O system is studied using the HSC Chemistry software package. At a low quartzite content in a charge, stable carbide phases TiC and SiC are found to form and prevent metallic phase formation. An increase in the quartzite content to 10–15% is shown to suppresses carbide formation and to promote the formation of silicides TiSi, TiSi₂, and Ti₃Si₃.

A three-stage technological scheme is proposed to produce qualified ferrosilicomanganese from a low-grade ferruginous manganese ore. At the first stage, selective solid-phase reduction of iron with hydrogen is carried out. Then, after separation melting of the ore metallization products to form a by-product metal and a manganese-containing slag, manganese and silicon are reduced from the slag with carbon to form ferrosilicomanganese. The results of thermodynamic modeling of the process of reducing manganese and silicon from a high-manganese slag are presented. Manganese monoxide is shown to react with silicon dioxide in the slag to form the Mn₂SiO₄ tephroite. Upon heating above 1750 K, the reduction of manganese from this compound is found to begin. As the temperature increases to 1800 K, manganese and silicon form the metallic Mn₅Si₃ phase. On further heating, the amount of manganese in a gas phase increases. Experimental results on producing ferrosilicomanganese from a slag after separation melting are presented. The possibility of producing ferrosilicomanganese without harmful impurities is shown. The synthesized alloy contains 9.29 wt % silicon, 48.72 wt % manganese, and iron for balance. However, a significant amount of manganese (25.89 wt %) is retained in the slag phase, indicating its incomplete reduction. The results obtained can be used in developing theoretical and technological foundations for processing ferruginous manganese ores with a high phosphorus content, which cannot be processed by the existing technologies.

A new hydrothermal lime–alkaline method for the desiliconization of quartz–titanium concentrates has been developed at the Baikov Institute of Metallurgy and Materials Science of the Russian Academy of Sciences (IMET RAS). Specific features of the conditions for the selective removal of finely dispersed SiO₂ depending on the initial mineral composition and iron content are shown for quartz–leucoxene and quartz–ilmenite concentrates from the Pizhem deposit. The pressure leaching of the concentrates is shown to proceed via the two-stage mechanism to form diverse calcium silicate hydrates nCaO⋅mSiO₂⋅xH₂O, which will govern the physical properties of the autoclave pulp.

The study examines how heat treatment regimes affect the mechanical properties and microstructure of as-cast and forged 20GML steel blanks. The mechanical properties of the test specimens after introducing secondary normalization are evaluated. The results show that changes in the temperature of secondary normalization significantly affect the mechanical properties and impact toughness of the as-cast blanks. The study identifies optimal heat treatment regimes for 20GML steel blanks to ensure high mechanical properties and impact toughness at temperatures down to –60°C.

Owing to its low density and good damping properties, magnesium is a promising material for industrial and medical applications. We propose a process for the fabrication of porous magnesium products via melt infiltration through water-soluble granules prepared from sodium chloride-, sodium carbonate-, and sodium hydrogen carbonate-based salts. The effect of granule composition on the corrosion resistance of porous magnesium during leaching has been studied, the granule composition has been optimized, and processes for the fabrication of granules and porous magnesium products have been proposed.

The results of a study of industrially melted orthorhombic titanium alloy VIT1 showed that these alloys are prone to hydrogen embrittlement, formation of surface and internal intergranular cracks, embrittlement of grain boundaries during deformation due to microsegregation of alloying elements to grain boundaries, and low-ductility or brittle fracture of blade forgings.