Russian Journal of Non-Ferrous Metals最新文献

The development of several defects such as hydrogen embrittlement, solidification cracks, porosity, blowholes, and undesirable metallurgical changes that occur in fusion welding can be elegantly mitigated by lowering the peak temperature in underwater friction stir welding. Therefore, this article delves into the effect of tool rotational speed on mechanical properties as well as the microstructural evolution of underwater friction stir welded AA1100-H18. Mechanical properties such as Rockwell hardness, tensile test and impact test as well as microstructural analysis through optical micrograph and scanning electron microscope were analyzed. The results showed that grains are refined and properties get enhanced at optimum rotational speed.

Copper precipitate comes from cyanidation wastewater treatment process using AVR (acidification-volatilization-regeneration) technology in a Korean gold plant and typically assays 44.53 wt % Cu, 5.56 wt % Fe and 16.81 wt % S. CuSCN and Cu₂Fe(CN)₆ are major copper compounds in the precipitate and in the past it has been sold as raw material for pyrometallurgy of copper. Low-temperature (( leqq {kern 1pt} 250^circ {text{C}})) sulfuric acid baking followed by acid leaching has been evaluated in order to recover copper and the experimental results showed that by acid baking under following condition: 250°C, 60 min and ratio of 98 wt % H₂SO₄/copper precipitate 2.4, ~98.5 wt % copper was released to the leach solution. During baking Cu₂Fe(CN)₆ preferentially reacted with sulfuric acid over CuSCN. The leachate containing Cu and Fe can be sent to conventional SX-EW process to produce electrolytic copper. And a little residue (~3.2 wt % of copper precipitate weight) is formed after acid leaching, Cu content in it is 20.8 wt % and Cu₂S and CuS are major copper compounds. Possible reactions were proposed for sulfuric acid baking of copper precipitate. HCN formed during baking is reoxidized to CO₂ and N₂, so recovery of cyanide during baking is of no significance. Based on this investigation, new process for treatment of copper precipitate is proposed for copper recovery. The process mainly consists of acid baking, acid leaching and SX-EW. And treatment of off-gas is needed in view of environmental issue.

Aluminum alloy is a material of particular significance within the domain of light weighting research. The present study investigates the effects of welding parameters on the forming and mechanical properties of static shoulder stir friction welded joints of 3 mm thick 6003 aluminum alloy. It was determined that the optimal quality of welds, characterized by their formation and absence of defects, was achieved through the utilization of static shoulder stir friction welding at speeds ranging from 3.000 to 4.000 rpm, with ω/v maintained within the range of 3 to 4. These results emphasize the importance of the welding parameters on the results.

In this study, a comprehensive method for processing lithium-ion battery electrode material is proposed, based on the selective cuprum leaching using an NH₄HCO₃ liquor followed by its sorption using the ion-exchange resin Purolite S930 Plus. Certain optimal conditions for ammoniacal leaching ensure cuprum recovery at approximately 90%. Loading tests demonstrated a high static sorption capacity of the resin—125.4 mg g^–1, while dynamic experiments and elution using H₂SO₄ showed the possibility of efficient cuprum recovery and resin regeneration. Additional analyses using IR and XPS spectroscopy confirmed the formation of stable coordination bonds between cuprum ions and the functional groups of the resin. The obtained results indicate the promise of the proposed technology for the industrial processing of spent lithium-ion batteries to recover valuable metals.

The effect of protective alkali and pH on gold extraction in cyanide leaching process of two stage roasting calcine of arsenic bearing gold concentrate was investigated. The results showed that the gold extraction was independent of protective alkali such as caustic soda, sodium carbonate and lime, and the effect of pH on gold extraction was obvious. If the pH of pulp is high, the arsenic concentration of cyanide leaching solution is increased to decrease gold extraction. The effect of arsenic concentration of solution on gold extraction was also investigated. When the leaching solution has no lead ion, the arsenic has no effect on gold extraction, but when the arsenic and lead exist in solution simultaneously, the effect of arsenic on gold extraction is high.

This study used the powder metallurgy method to produce particle-reinforced hybrid Al metal matrix composites (HAMMCs). The synergistic effects of adding graphite-TiO₂ and ZrO₂ reinforcement to the Al matrix on the microstructure development, hardness, and wear behavior of hybrid aluminum metal matrix composites were researched. Hybrid composite samples produced after sintering, phase and microstructure analysis, density measurement, hardness, and wear behavior have been studied experimentally. Microstructural observation shows reinforcements are partially homogeneously distributed in the Al matrix. Dual-oxide reinforcement improved hardness more remarkably than mono-oxide reinforcement in the produced samples. The highest hardness value is obtained in the Al–5% TiO₂ + 5% ZrO₂ + 2% C composite. The lowest COF values of composite samples are obtained with dual-oxide reinforcement. Al–5% TiO₂ + 5% ZrO₂ + 2% C composite has the highest wear resistance.

Present study focuses on the fabrication and evaluation of graphene nanoplatelets and titanium dioxide nano powder-reinforced aluminium-zinc-magnesium alloy-based nanohybrid metal matrix composites using the cost-effective and scalable stir casting technique with the objective to enhance tribological performance and corrosion resistance. The tribological properties were evaluated under 10 and 20 N loads at 300 and 600 rpm conditions. Wear and coefficient of friction shows significant improvement. Minimum wear is reported in 2% graphene nanoplatelets and 3% titanium dioxide samples at 10 N and 300 rpm conditions, whereas coefficient of friction is minimum in the same composition at 20 N 600 rpm conditions having values of 0.0016 mm³ min^–1 and 0.28 respectively. Scanning electron microscopy images revealed wear mechanisms at 10 and 20 N loads, showcasing reduced wear scars and smoother surfaces in higher reinforced composites. Minimum surface roughness observed is 1.71 µm. Corrosion resistance was also notably enhanced, as confirmed by scanning electron microscopy images analysis of corroded surfaces. The lowest corrosion rate observed is 0.83 mmpy at 2% graphene nanoplatelets and 3% titanium dioxide reinforced sample. Artificial neural networks and multiple linear regression were employed, showing excellent correlation with experimental data for accurate property predictions. The results demonstrate that the incorporation of present reinforcements substantially improves wear resistance, lowers friction coefficient, and mitigates corrosion in saline environments.

The effect of Gd microalloying on the microstructure, mechanical behavior, and structural evolution during hot deformation in the (α₂ + γ) phase field has been investigated on two experimental β-solidifying alloys based on γ–TiAl – Ti–45Al–2V–1Nb–1Zr and Ti–45Al–2V–1Nb–1Zr–0.2Gd (at %). The addition of Gd led to a reduction in the average size of plate-like (α₂ + γ) colonies from 250 to 140 μm, and the inter-lamellar spacing decreased from 160 to 110 nm in the as-cast state. It was shown that the reduction in the average colony size resulted in a decrease in the yield strength and peak stresses during hot deformation, with this effect being more pronounced at lower deformation temperatures. Additionally, the introduction of Gd resulted in the fraction of recrystallized/spheroidized volume increase of the forming α₂/γ-phase grains/particles and also their size reduction.

To address the defects and damage to high-temperature K4169 alloy components during casting and processing, as well as during service, laser deposition repair of K4169 alloy was carried out and the effect of heat treatment on the microstructure and properties of the repaired samples was investigated. After aging heat treatment, a large number of γ' phases and a small number of γ'' phases precipitated in both the repair zone and the substrate zone, but the δ phase was still observed only in the substrate, the number did not change significantly, the strength of the repaired sample improved, and the plasticity decreased. After solution + aging heat treatment, more γ'' phases precipitated from the sample, which led to a further increase in strength. The precipitation of the δ phase was observed in the repair zone, the number and distribution scope of δ phases in the substrate zone increased. In addition, the plasticity was greater than that of the aged sample because of the dissolution of the brittle Laves phase and the cutting effect of the δ phase.

We employ first-principles calculations to investigate the structural stability and electronic properties of cubic zinc oxide (ZnO) and Zinc sulfide (ZnS) heteroclusters adsorbed with H₂O molecule. A comprehensive investigation on H₂O grabbing by ZnO/ZnS heteroclusters was carried out using DFT computations at the CAM–B3LYP–D3/6–311+G (d, p) level of theory. The notable fragile signal intensity close to the parallel edge of the nanocluster sample might be owing to H/OH binding induced non-spherical distribution of ZnO or ZnS heterocluster. The hypothesis of the energy adsorption phenomenon was confirmed by density distributions of CDD, TDOS and ESP for ZnO/ZnO–H₂O or ZnS/ZnS–H₂O. A vaster jointed area engaged by an isosurface map for H/OH adsorption on ZnO or ZnS surface towards formation of ZnO–H₂O or ZnS–H₂O complex due to labeling atoms of O1, Zn15, O27 or S27, H29, H30. Therefore, it can be considered that zinc in the functionalized ZnO or ZnS might have more impressive sensitivity for accepting the electrons in the process of H/OH adsorption. It is considerable that when all surface atoms of ZnO or ZnS are coated by OH and H groups, the semiconducting behavior is recovered. Our results open up the possibility of tailoring the electronic properties by controlling the surface adsorption sites.