Highly dispersed, fluorite-like solid solutions (Ce0.80Zr0.10La0.05M0.05O2 – δ), where M = Nd, Sm or Gd, were synthesized by co-precipitating metal hydroxides, followed by heat treatment. The chemical composition of the resulting materials was confirmed by inductively coupled plasma optical emission spectroscopy. X-ray phase analysis confirmed the formation of the Ce0.80Zr0.10La0.05M0.05O2 – δ solid solutions, where M = Nd, Sm or Gd, based on the cerium dioxide crystal lattice. According to transmission electron microscopy data, the average particle size is 13 ± 2 nm. The synthesised materials have a mesoporous structure with a specific surface area of 83–86 m2/g, a total pore volume of 0.101–0.104 cm3/g and a pore diameter of 3.6–3.8 nm. The catalysts exhibit high activity in the complete oxidation of methane (model mixture composition: CH4 – 1 vol.%; O2 – 8 vol.%; N2 – balance). A correlation has been established between the catalytic activity of solid solutions and the ionic radius of the rare earth dopant M. The activity of synthesised solid solutions (Ce0.80Zr0.10La0.05M0.05O2 – δ), where M = Nd, Sm or Gd, decreases in the order Gd → Sm → Nd. The highest activity is observed in the presence of the Ce0.80Zr0.10La0.05M0.05O2 – δ catalyst, which has the smallest ionic radius of the M3+ dopants studied. The temperatures at which 50% and 99% conversion are achieved in the presence of the sample are 356 °C and 477 °C, respectively. The application of Ce0.80Zr0.10La0.05M0.05O2 – δ as a carrier for the active component, palladium, shows promise. The catalytic activity of 0.3% PdO/Ce0.80Zr0.10La0.05M0.05O2 – δ exceeds that of the industrial analogue, 0.3% PdO/γ-Al2O3, demonstrating the feasibility of using the synthesized solid solution as a carrier for the active component. The authors would like to thank the Center for Collective Use at the D.I. Mendeleev Russian Chemical Technology University for conducting research on the elemental composition of the samples.The work was carried out as part of a state assignment from the Ministry of Science and Higher Education of the Russian Federation (FSSM-2023-0004 “Scientific foundations of transition metal-based catalysis systems for promising redox reactions of selective conversion of hydrocarbons and oxygen-containing organic substrates”).

The results of a study on a suspension containing industrial oil I-20A and copper nanopowder at concentrations of0.05, 0.1, 0.2, 0.3 and 0.5 (wt.%) are presented in the paper. The work simulated a mode of insufficient lubrication in the friction zone – 0.1 ml of lubricant was added to the friction zone and the lubricant was not renewed throughout the experiment. The tests were carried out on a friction machine SRV-3 at a load of 200 N, an amplitude of 3 mm and a frequency of 5 Hz. The addition of 0.1% by weight copper nanoparticles to industrial oil showed the best results in reducing the coefficient of friction and wear compared to the base oil. The mechanism is explained by the deposition of small copper particles in the wear area and the improvement of tribological characteristics, this is confirmed by the analysis of wear surfaces on a scanning electron microscope. At concentrations above 0.1%, particle aggregation occurs and, as a result, abrasive wear increases. At copper concentrations less than 0.1%, only partial film formation occurs, and the uneven distribution of particles does not provide any advantages over the base oil. Copper nanoparticles are a promising material for improving the lubricating properties of oils and restoring surfaces. Their use allows you to reduce friction, reduce wear and extend the service life of mechanisms. However, for widespread adoption, issues of aggregation and cost need to be addressed, and further research into long-term effects needs to be conducted.

The article presents the results of studies of the structure and properties of industrial ingots made of AD31 alloy, which are modified with alloying rods obtained using the technology of ingotless rolling and extrusion (IRE) from scrap of extruded profiles made of AD31 alloy. This method and device are described for combining continuous casting, rolling, and extrusion operations in a single unit. As equipment for obtaining rods with a diameter of 9 mm from secondary waste of AD31 alloy, an experimental and industrial installation CRE-400 with a rolling roll diameter of 385 mm was used. For the production of rods, technological parameters of the IRE process obtained as a result of numerical modeling of the studied process were used. To produce ingots, the company used experimental and industrial equipment from United Company Rusal Engineering and Technology Center (RUSAL ETC). In the course of experimental studies, experimental ingots with a diameter of 100 mm were obtained from the AD31 alloy, modified with a rod made using the IRE technology from secondary waste of the AD31 alloy. Tensile tests were performed on these ingots, and the mechanical properties were obtained, as well as the macro- and microstructure of the metal was studied. It has been established that the introduction of a 3–4% AD31 rod made of the same alloy into the melt, obtained by the IRE method from the scrap of extruded profiles of the same alloy, reduces the grain size to 234–349 μm, depending on the conditions of the rod introduction and the choice of ingot casting parameters. Comparison with the initial macrostructure of the unmodified ingot showed that the introduction of a rod of the same composition obtained by the new method leads to the formation of a fine-grained structure of the ingot, which indicates the presence of a modifying effect when using a rod obtained by the IRE method. At the same time, the obtained high level of mechanical properties of the metal of these ingots makes it possible to use them for the production of extruded profiles from the AD31 alloy. The work has been carried out with the financial support of the Russian Science Foundation and the Krasnoyarsk Regional Science Foundation under grant No. 24-29-20136.

The technology of oxygen blowing of pre-hydrogenated aluminum alloy melt allows to obtain a composite material in situ, saturated with submicroscopic Al2O3 particles. The key factor of the technology is the presence of iron in the melt, which negatively affects the strength of the oxide film, which allows to obtain isotropic particles of aluminum oxide, and not extended films. Until now, the technology was used only for cast products based on silumin AlSi7Fe. It is proposed to use an Al – Fe alloy with an iron content above 1.5% for obtaining a composite for cold rolling technology. The alloy is also saturated with titanium due to the introduction of TiH2 for hydrogenation. As a result, a butterfly-shaped structure is formed in the metal, presumably by the following mechanism: the butterfly body is an Al3Ti intermetallic compound, which precipitates in the melt first and collects oxide particles and iron-containing intermetallic compounds. The composite demonstrates grinding of iron intermetallic compounds at least 3 times relative to the original alloy. The content of the oxide component is 8 times lower than on the initial alloy of the AlSi7Fe system due to a significantly smaller thickness of the oxide film. This leads to a significant reduction in the blowing time, the total duration of melt processing, including hydrogen saturation, was 15 min. The samples were subjected to cold rolling, the foil thickness achieved was 19 μm. The obtained rolled product with a thickness of about 150 μm exceeds the original alloy in mechanical properties (σu – 269 MPa against 174 MPa of the original alloy), and the hot-rolled AlSi7Fe-Al2O3p composite (σu – 250 MPa).

This study presents the results of phase composition determination for four alloys in the Al – Mg – Zn – Ca – Cu system. The analysis was performed using both computational (Thermo-Calc) and experimental (DSC, SEM) methods. According to cooling curves based on the Scheil model, the studied alloys exhibit similar liquidus temperatures (613–620 °C) but different solidus temperatures, which decrease with increasing copper content. Conversely, the non-equilibrium solidus temperature increases. These findings align well with DSC results, indicating that solidus temperature shows significant differences only in copper-containing alloys, with higher values by 20–30 °C. The cast microstructure of all alloys is characterized by a degenerate eutectic nature, with an ave rage crystal size up to 4 μm by Feret, and the calculated volume fraction of secondary phases did not exceed 12 vol.%. The aluminum matrix was enriched with magnesium, zinc, and copper, while zinc content remained unchanged with increasing calcium and copper concentrations. As calcium content increased to 1.5%, zinc solubility in the Al4Ca phase decreased, reaching a minimum at 1.5% Ca and 1% Cu. Copper solubility increased with its content in the alloy; however, after quenching at 440 °C for 3 hours, zinc and copper solubility in the Al4Ca phase increased. In copper-containing alloys, two additional copper-containing phases were identified after furnace cooling, besides (Al,Zn,Cu)4Ca and T (AlMgZnCu). At 0.5% Cu, the AlCuMg phase was detected, which was absent at 1% Cu; instead, a ternary compound Al27Ca3Cu7 formed, incorporating up to 6 at.% zinc. The study was carried out using the funds of the Russian Science Foundation grant No. 23-79-01055 (scanning microscopy, differential scanning calorimetry) and the funds of the P.L. Kapitsa grant of the Moscow Polytechnic University, implemented within the Priority 2030 programme (melting and casting, heat treatment). The structure study was carried out using the scientific equipment of the CKP NRC “Kurchatov Institute - IREA”.

The article discusses the wide application of aluminum alloys in various industries, as well as the necessity to increase their strength to meet the requirements of modern technologies. An important point is to investigate the evolution of nanoscale precipitates in AA7075 alloy, in order to improve the mechanical properties of the material. Manufacturing of aluminum alloy parts by additive method allows you to achieve a high level of productivity and, if necessary, to exceed mechanical standards for these materials. Particular attention is paid to structural phase state studies, which are necessary for the development of new technologies based on additive manufacturing, such as surface cladding of aluminum alloys. The study showed that the surface cladding mode (Ar flow rate ≈ 10 l/min, surface cladding speed 100 mm/min, current — 70–80 A, voltage — 15.8 V, wire feed speed — 4 m/min) provides the best results in terms of quality and stability of the cladding process. The manufactured blanks had a dense structure with no visible cracks and the porosity percentage was low. This indicates to the possibility of using this mode for the production of highquality cladding materials. The MIG welding process using constant optimal technological parameters allows to obtain aluminum alloy AA7075 with desired microstructural properties by additive manufacturing method. Strengthening phases in the alloy help prevent crack growth during mechanical testing, and the morphology of equiaxed grains may contribute to uniform stress distribution and increase the strength of the material. It is important to note that large columnar grains in the fusion zones can affect the mechanical properties of the material and additional studies may be required to determine their effect on the overall strength of the alloy. The study was funded by the Russian Science Foundation grant No. 22-79-10245, https://rscf.ru/project/22-79- 10245/.

In the present work, the microstructure of Co 20 Cr 20 Fe 10 Mn 30 Ni 20 high-entropy alloy with increased Mn content and decreased Fe content, which was obtained by vacuum induction melting, was studied. The study evaluates the effect of Fe and Mn content percentages on the microstructure and mechanical properties of high entropy alloy (HEA). The relationship between the microstructure (formation of solid solution phases) and mechanical properties of HEA in comparison with the high-entropy equiatomic Cantor alloy is investigated. Studies of the structure, phase and chemical composition of the material were obtained using X-ray diffraction and scanning electron microscopy. It is shown X X that the studied alloy is a material consisting of a single-phase solid solution with a face-centered cubic lattice and a structure represented in the form of dendrite branches of the first, second and third order. Energy dispersive X-ray X X spectroscopy revealed that the dendrite axes are enriched with chromium, iron and cobalt atoms, while manganese and nickel predominate in the interdendritic areas. It is likely that during crystallization process, such elements as manganese and nickel have time to be redistributed and released in the form of second-phase particles in the interaxial spaces of dendrites. Destruction of the material is represented by ductile fracture with the content of deep fracture holes, indicating high plasticity of the material, as well as the presence of globular oxide inclusions, which are more enriched in manganese, oxygen and chromium atoms. According to the conducted tensile tests, it was found that the samples of Сo 20 Cr 20 Fe 10 Mn 30 Ni 20 mainly have high (more than 80%) plasticity and V 0.2 = 236 MPa, V lim = 478 MPa, respectively. The result also shows that the decrease of Fe and increase of Mn in the alloy increases the strain hardening rate, which further increases the embrittlement degree. It is found that the composition of the area containing non-metallic inclusion in Co 20 Cr 20 Fe 10 Mn 30 Ni 20 alloy is more enriched in manganese, oxygen and chromium.

The possibility of processing of 1.09 g/t gold content ore from Central Kazakhstan by cyanidation on activated carbon has been studied. The results of studies on ore phase composition are presented: the total amount of cyanidable gold in the sample is 80.59%; the share of refractory gold not recoverable by direct cyanidation is 19.41% of the total mass of metal; the total share of free gold with clean surface at ore size of 95% grade -0.071 mm is 36.78%. Based on the results of Preg Robbing Adsorption Kinetics test, the preg robbing property of ore is established. It was found that during the ore cyanidation process, the dissolved gold has a reverse deposition effect on the ore. It is shown that when the contact time of ore with solution is increased up to 60 min, the gold allocation to ore components increases from 23 to 50%. Experiments on cyanidation of ore on activated carbon in CIP and CIL modes in a bottle-type agitator at sodium cyanide flow rates of 0.5 kg/t, 0.75 kg/t and 1.25 kg/t were carried out. Norit RO 3515 activated carbon was used as a sorbent. In all experiments CaO was added to the leaching solution at the rate of 1.2 kg/t. The acidity of the solution was maintained at pH = 11.5. On the basis of comparative test results in CIP and CIL modes the superiority of ore cyanidation in CIL mode is shown. The optimal parameters of ore cyanidation in CIL mode were established: duration = 12 hours; NaCN consumption = 0.5 kg/t; acidity pH = 11; oxygen concentration in the solution 11.5 mg/l. Gold recovery in solution was more than 77%.

The weldability of hot-rolled sheets of alloy 1580 by friction stir welding was investigated. The test blanks were cut from 6.0 mm thick sheets, which were produced under industrial conditions by hot rolling of large-size ingots with dimensions of 300×1445×2200 mm at the "SGP Kvarto 2800" mill. Cards of 210×297 mm size were cut from the sheets and then roasted under two regimes: at 300 °C for three hours and at 350 °C for three hours. The work solved the problems of determining the mechanical properties of welded samples by tensile tests, investigating the structure of the weld by metallographic and electron microscopic methods, assessing the quality of the weld by radiographic analysis and technological tests for static bending. It has been established that the use of the friction stir welding method for joining 1580 alloy sheets allows to obtain high quality of the welded seam. Mechanical tests have shown that the strength of welded joints obtained by the FSW method is almost at the level of the base metal strength and does not depend on the localization of the fracture point. The samples after welding withstood bending tests without cracks along the entire length of the weld, both by bending at an angle of 150° with a mandrel, and after continued testing by static bending in a vise to parallelism of the sides.

The issue of expanding the range of effective flotation reagents remains relevant due to the deteriorating ore base and the involvement in processing of refractory ores with complex mineral composition. In recent years, complexing reagents capable of forming strong complexes with transition metal ions have been of increasing interest. At that, insertion of an additional functional group into the structure of the reagent molecule can provide a more complete extraction of the useful component. The purpose of this work is to evaluate the efficiency of using nitrogen-containing monoderivatives of dicarboxylic acids from the amide class as collecting agents for flotation of copper-nickel ores. The synthesis of monoalkylamides of succinic and phthalic acids with different hydrocarbon radicals as well as their complexes with copper and nickel was carried out. The formation of complexes was confirmed by extraction method, chemical analysis and Raman spectroscopy. It was noted that during the extraction of copper and nickel by the reagents under consideration, an effective process of complexation in the organic phase takes place. Their interaction with the surface of copper-and nickel-containing minerals was evaluated by the method of frothless flotation in comparison with the traditional collector. It is shown that monoalkylamides are more efficient towards nickel-containing minerals. Flotation tests on a sample of finely disseminated copper-nickel ore with copper content of 0.182% and nickel content of 0.479% have shown that succinic acid monoalkylamide as an independent collector with its own foaming properties and in a mixture with butyl xanthate shows greater selectivity. The best results were obtained when it was used in a mixture with butyl xanthate at a ratio of 70 : 30.