The paper considers the use of deactivated nickel-containing catalysts based on Al2O3 as a significant raw material resource of one of the most important metals. The research highlights the features of this secondary nickel source that determine the acceptable methods of processing such raw materials. The effect of fluxing additives on the properties of the melt containing catalysts prepared beforehand has been studied subject to limitations as to their list (lime, fluorspar) in order to implement a pyrometallurgical method of metal extraction featuring by a relatively small amount of additives themselves. Due to induction heating used in combination with a graphite crucible, adding the total amount of fluorspar and marble additives close in mass made it possible to obtain the melt at a temperature slightly higher than the nickel melting temperature. In this case, the level of metal losses was about 2 %, which indicates the applicability of this method in laboratory conditions to ensure correct incoming analysis. It was proposed to use the pyrometallurgical method on an industrial scale using closed arc heating. To confirm this conclusion, experiments were conducted with a representative (more than 100 kg) amount of catalyst using a tailored arc furnace. Graphite chips were used as a reducing agent. The necessity of electrical matching of the load with the power source resulted in some adjustment of the fluxing additive ratio towards a reduction of calcium oxide content. As a result of a series of experiments, nickel with an up to 5 % iron admixture, similar in composition to the metal formed in the graphite crucible, was obtained. The presence of iron was caused by the fundamentally distinctive capability of the pyrometallurgical technology to reduce unstable compounds. Therefore it was suggested to use this metal for ferronickel production. The use of scarce fluorspar is justified by the fact that the resulting slag can be in demand in the production of fluxes for the electroslag remelting process.

The paper presents the results obtained in the thermodynamic modeling of converting copper-nickel matte (11.3 wt.% Ni + Cu + + Co, 61.5 wt.% Fe, 25.9 wt.% S) produced by joint smelting of oxidized nickel ore and sulfide copper ore. Calculations were made in the approximation of ideal molecular solutions using the HSC Chemistry software package (Outotec Research Oy, Finland). The possibility of low-iron matte, converter slag and gas phase separation was shown. Estimated conditional equilibrium constants of exchange reactions between low-iron matte and slag (K_Ni/Fe = 0.004÷0.005, K_Co/Fe = 0.056÷0.099) are close to ideal values. Statistical data processing was carried out using the mathematical experiment planning method. The converting temperature (t = 1100÷1300 °C) and iron and sulfur oxidation completeness level (q = 0.9÷1.0) determining the air and flux (SiO₂) consumption were chosen as the factors to study. Obtained mathematical models of the process were used for its optimization. It was shown that the best converting performance can be achieved at t = 1150 °С and q = 0.950 when the low-iron matte contains 70.7 wt.% Ni + Cu + Co. At a yield of 8.74 % of the charge mass, the nickel, copper and cobalt recovery rates are 67.9, 97.9 and 9.1 %, respectively. The supposed air consumption (145.1 m³ (under normal conditions) per 100 kg of matte) and SiO₂ (34.4 kg per 100 kg of matte) as well as slag yield (89.1 % of the charge mass) are close to working regime parameters. The results of the study confirm the possibility of cost-effective processing of poor copper-nickel matte and after experimental verification they can be used to develop automation flowcharts for converter departments at existing and designed production facilities.

Electrochemical reduction of hydrogen (hydronium ion) was carried out on zinc, aluminum and copper cathodes from acidic aqueous solutions containing sulfuric acid (0.09, 0.18 and 0.36 mol/l) to study the effect of electrolyte acidity, the type of cathodes used and potential values on electrolysis indicators. The studies were carried out on the potentiostat using a three-electrode cell under conditions of intensive electrolyte stirring with a magnetic stirrer. At the initial stage, electrolysis was performed in the following modes: potentiodynamic measurements at a sweep rate of 1 mV/s in the potential range Е = –(700÷850) mV on a copper and aluminum electrode and Е = –(1000÷1150) mV on a zinc electrode. In the indicated potential range, hydronium discharge parameters at each cathode were calculated: Tafel slope, apparent transfer coefficients and exchange currents. Dependences of these parameters on electrolyte acidity were considered. Average values of steady state potentials were obtained, which, similar to the apparent exchange current, significantly depended on the cathode material: –923.1 mV (zinc cathode); +36.1 mV (copper cathode), and –603.7 mV (aluminum cathode) (AgCl/Ag). The effect of surfactants on all the kinetic parameters considered was shown. The order of the reaction with and without surfactant additives was determined. At the next stage, the electrochemical parameters of hydronium discharge on the copper electrode only were compared. It was shown that the electrochemical parameters significantly depend on the cathodic potential range where they are determined, and on the methods used for their calculation. It was noted that the process proceeds in the region of mixed kinetics. As the electrode polarization decreases, the hydrogen discharge mechanism changes, while the proportion of electrochemical kinetics will increase in the region of mixed kinetics. We suppose that the data obtained can also be of practical importance for the zinc electrolysis technology. The data obtained in this research on the electrochemical parameters of hydrogen discharge in a wide range of potentials on cathodes made of different metals as well as on the effect of electrolyte acidity on the behavior of surfactants during electrolysis will expand knowledge about the zinc electrolysis technology.

A thermodynamic assessment of the effect of alloying elements (Si, Mg, Cu, Ti) on phase formation processes during the production and liquid-phase processing of cast aluminum matrix composite materials with exogenous reinforcement (Al–SiC, Al–B₄C) was carried out. It was shown that without suppressing Al–Si–C and Al₄C₃ carbide formation in the range of carbon concentrations from 0 to 4.5 wt.%, the equilibrium phase composition of Al–SiC composites in the solid state at 423 to 575 °C lies in the (Al) + Si + Al₄SiC₄ three-phase region, and the Al₄SiC₄ ternary carbide is replaced by the Al₈SiC₇ compound at a temperature below 423 °C. SiC and B₄C phases in Al–SiC–Cu and Al–B₄C–Cu systems are stable in the entire crystallization range and do not interact with aluminum or copper. In the Al–SiC–Mg system, the crystallization of composites containing more than 0.58 wt.% magnesium ends in the (Al) + Al₃Mg₂ + SiC + Mg₂Si four-phase region. In the Al–SiC–Ti system, the end of crystallization is observed in the (Al) + Al₃Ti + SiC three-phase region. In the Al–B₄C system, once Al₄C₃ phase formation is suppressed, aluminum borides are formed with a deviation from the concentrations of elements providing 10 vol.% B₄C towards boron increase and free carbon is formed with a deviation towards boron decrease. Under equilibrium conditions, Al–B₄C–Si system crystallization ends in the (Al) + B₄C + AlB₁₂ + Al₈SiC₇ four-phase region (at a silicon content of up to 0.67 wt.%, and in the (Al) + Si + AlB₁₂ + Al₈SiC₇ region at a higher silicon content. In the Al–B₄C–Ti system, crystallization ends in the (Al) + TiB₂ + B₄C three-phase region at a titanium content of less than 0.42 wt.%.

This article studies the mechanism of thin-walled workpiece deep drawing in the mould with a conical die and determines the forming limit state that occurs at the time of the bottom detachment in the radius part of the punch when stresses in the meridional direction reach their maximum value. This condition is determined by a decrease in the workpiece edge size at the stage of slow material hardening and a decrease in the workpiece flange area that are main factors hindering the process. This condition makes it possible to establish a criterion used to determine the limiting drawing ratio (ratio of the diameter of the workpiece to the diameter of the part), namely: equality of meridional stresses in the punch radius rounding area and the material tensile strength. The paper establishes the effect of the workpiece material strength properties, friction and die taper on the limiting drawing ratio. A change in the plastic and strength properties of the BrKh08 heat-resistant copper alloy (tensile strength, yield strength) does not affect the material hardening constant values and practically does not affect the limiting drawing ratio. The paper uses a comprehensive research method including theoretical analysis and modeling in the ANSYS/LS-DYNA software with input data for the 1.35 mm thick workpiece 100 mm in diameter made of BrKh08. The article presents computer simulation stages indicating main process parameters such as the workpiece material model, mechanical properties, type of elements, kinematic loads, conditions of contact interaction between elements, etc. Process simulation results confirmed theoretical conclusions necessary for the process implementation without part defects.

This paper presents comparative studies of the structural and mechanical properties of the new Ti–10Mo–8Nb–6Zr β-Ti alloy subjected to traditional cold rotary forging and equal channel angular pressing (ECAP) at 250 °C. The main phase in the initial hardened state after forging and ECAP is the BCC β phase. A broadening of the β phase X-ray lines and TEM data indicate a reduction in the structure and an increase in the concentration of lattice defects after deformation treatments. In the initial state, the alloy has an ultimate tensile strength of about 700 MPa, offset yield strength of 450 MPa and elongation at break of ~30 %. As a result of forging, the ultimate tensile strength and offset yield strength of the alloy increase to 1230 and 950 MPa, and after ECAP – to 1280 and 1270 MPa, respectively. At the same time, the elongation is reduced to 6 % after ECAP. A significant increase in the strength of the Ti–10Mo–8Nb–6Zr alloy after ECAP makes it more promising for use in medicine.

Additive manufacturing, which includes a set of technologies for manufacturing complex-shaped products with the required set of properties, is currently widely developed. Most additive technologies are associated with the manufacture of the product by melting and fusion of metal powder particles due to laser irradiation. Al–Ca, Al–Ce, Al–La, and Al–Ni eutectic aluminum alloys featuring excellent casting properties are supposedly promising for use in additive technologies. However, there is very little information on the effect of laser processing on such eutectic structures in the literature. In this regard, the paper investigated the effect of laser irradiation on the structure and mechanical properties of samples made of eutectic compositions, namely Al–8%Ca, Al–10%La, Al–10%Ce, and Al–6%Ni. This was achieved by continuous laser modification of their surfaces. The hardening level was evaluated by measuring the microhardness of the modified surface. The mechanisms of sample fracture under tensile testing were established. It was shown that the distribution of the second component in the structure of modified sample surfaces of all the four alloys becomes more uniform compared to the base metal structure. In the Al–8%Ca alloy, the greatest hardening effect was observed, which, however, contributes to embrittlement under tensile stress. However, the modified Al–8%Ca alloy is of interest because of its increased hardness and possibly increased wear resistance. On the contrary, laser modification of the Al–10%Ce, Al–10%La, and Al–6%Ni alloy sample surfaces provides a lower hardening effect, but increases their tensile strength with the formation of a ductile or mixed ductile-brittle fracture. The results obtained confirm the prospects of using the Al–Ca, Al–Ce, Al–La, and Al–Ni alloys in additive manufacturing.

The studies carried out to explore the modifying effect on the surface of a hard alloy, surface alloying and thermochemical treatment of metal, thermal diffusion saturation, vacuum ion-plasma deposition demonstrated changes in surface roughness and performance. This paper used roughness to evaluate the behavior of various hard alloy groups when heated in various media. The samples were 5× 5× 35 mm bars and 15.8 ×15.8 mm tetrahedral plates made of VK8 and T14K8 hard alloys. Surface roughness parameters were measured on the profilometer implementing the contact (probe) method. Roughness values obtained were analyzed in the Microsoft Excel system based on an integral percentage and histograms were constructed. The effect of the heating medium on the surface roughness was studied both on bars and plates (with and without holes) using the saturating element/buffer substance (50–100 % BaCl₂) melt. K₄(Fe(CN)₆ potassium ferrocyanide and Na₂B₄O₇ borax were used as a saturating element (25 %). Microhardness and cutting wear were determined directly on the products (after determining the heating media effect on roughness). The heating of VK8 and T14K8 hard alloys in various media increases roughness and reduces cutting wear up to 2 times. The structure of initial materials before and after heating in various melts was studied using the JCM-6000 scanning electron microscope (Jeol Ltd., Japan) at a magnification of 1000–3000×. Plates in their initial state and after heating in various melts were subjected to resistance tests on the 1A616 screw-cutting lathe by face turning of an axle billet made of OS steel (similar in structure and properties to St45) 210 ×1650 mm in size of continuously cast metal (GOST 4728-2010). X-ray diffraction analysis of the VK8 hard alloy after heating in various media demonstrated the absence of changes in the phase composition. Along with this, there was a slight change in the carbide phase fine structure parameters of the alloy, namely a slight increase in micro-stresses with a simultaneous decrease in mosaic blocks.