Search Results (140)

In this paper, dedicated material models were developed and verified for three melts of EN AW-7021 alloy, differing in zinc and magnesium content, for tube extrusion conditions. Based on the plastometric tests, it was found that in the studied range of strain parameters, the analyzed melts of the same aluminum alloy showed different sensitivity to strain rate and temperature. In addition, a significant effect of magnesium and zinc content on the plasticity of the tested material was observed. Therefore, dedicated material models describing stress changes were developed for each melt analyzed. The models were then implemented into the material database of the QForm-Extrusion^® program, which was used for the theoretical analysis of the industrial extrusion process. In order to verify the results of numerical calculations, industrial tests of the extrusion process were carried out. The force parameters and the rate of the extrusion process were mainly analyzed. The use of dedicated material models for each melt contributed to the accuracy of numerical modeling. A high degree of compliance was obtained regarding the theoretical and experimental extrusion force and the velocity of metal flowing out of the die cavity, among others. Full article

Both ZnO and BeO semiconductors crystallize in the hexagonal wurtzite (wz), cubic rock salt (rs), and zinc-blende (zb) phases, depending upon their growth conditions. Low-dimensional heterostructures ZnO/Be_xZn_1-xO and Be_xZn_1-xO ternary alloy-based devices have recently gained substantial interest to design/improve the operations of highly efficient and flexible nano- and micro-electronics. Attempts are being made to engineer different electronic devices to cover light emission over a wide range of wavelengths to meet the growing industrial needs in photonics, energy harvesting, and biomedical applications. For zb materials, both experimental and theoretical studies of lattice dynamics ${\mathsf{\omega }}_{\mathrm{j}}\left(\overrightarrow{\mathrm{q}}\right)$ have played crucial roles for understanding their optical and electronic properties. Except for zb ZnO, inelastic neutron scattering measurement of ${\mathsf{\omega }}_{\mathrm{j}}\left(\overrightarrow{\mathrm{q}}\right)$ for BeO is still lacking. For the Be_xZn_1-xO ternary alloys, no experimental and/or theoretical studies exist for comprehending their structural, vibrational, and thermodynamical traits (e.g., Debye temperature ${\mathsf{\Theta }}_{\mathrm{D}}\left(\mathrm{T}\right);$ specific heat ${\mathrm{C}}_{\mathrm{v}}\left(\mathrm{T}\right))$. By adopting a realistic rigid-ion model, we have meticulously simulated the results of lattice dynamics, and thermodynamic properties for both the binary zb ZnO, BeO and ternary Be_xZn_1-xO alloys. The theoretical results are compared/contrasted against the limited experimental data and/or ab initio calculations. We strongly feel that the phonon/thermodynamic features reported here will encourage spectroscopists to perform similar measurements and check our theoretical conjectures. Full article

Zinc (Zn)-based alloys are considered promising bioresorbable materials for intracorporeal implants due to their good biocompatibility and suitable degradation rate in physiological environments. However, their broader application is hindered by insufficient mechanical properties, which are essential for fulfilling the therapeutic function of bioresorbable implants. This study investigates the effect of severe plastic deformation on the microstructure and mechanical properties of as-cast Zn–0.1Mg (wt.%) alloy. The as-cast alloy, characterised by a coarse-grained microstructure with intermetallic phases at grain boundaries and low strength and ductility, was subjected to two passes of Equal Channel Angular Pressing (ECAP). The intense plastic deformation transformed the coarse-grained structure into an ultrafine-grained solid solution matrix. This substantial microstructural refinement led to a significant enhancement in mechanical performance. The yield strength (YS) and ultimate tensile strength (UTS) more than doubled, reaching 198 MPa and 215 MPa, respectively. Remarkably, the elongation increased from 2.2% to 187% in tensile testing. These findings confirm the beneficial effect of grain refinement and dynamic recrystallisation on the mechanical behaviour of bioresorbable Zn–0.1Mg alloy and highlight the high potential of ECAP processing for optimising the mechanical properties of Zn-based biodegradable materials. Full article

The novel pyridine oxime-based complexing agents 2-pyridinecarboxaldehyde oxime, 2-acetylpyridine ketoxime and 2-pyridine amidoxime were synthesized for alkaline Zn-Ni alloy electrodeposition, outperforming conventional citrate/TEPA systems in corrosion resistance and microstructural control. The N,O-bidentate chelation mechanism governs metal ion reduction kinetics via diffusion-limited pathways, enabling γ-phase Ni₅Zn₂₁ intermetallic formation and nanocrystalline refinement. Electrochemical and microstructural analyses demonstrate suppressed random nucleation and hydrogen evolution side reactions, leading to enhanced charge transfer resistance and reduced corrosion current density. Notably, 2-pyridine amidoxime achieves ultrasmooth surfaces through defect-free nanocluster growth, while 2-pyridinecarboxaldehyde oxime maximizes γ-phase crystallinity. The synergy between grain boundary density and surface integrity establishes a dual protection mechanism combining barrier layer formation and active dissolution suppression. This work advances microstructure engineering via coordination chemistry, offering a breakthrough over traditional zincate electroplating for high-performance anti-corrosion coatings. Full article

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries. Full article

Magnesium-based alloys are considered to be promising materials for the fabrication of temporary bone repair medical implants. The AZ31 magnesium-based (AZ31-Mg) alloy contains 3% aluminum and 1% zinc in its microstructure, which gives it mechanical strength and corrosion resistance. Nonetheless, the corrosion rate is high, which can lead to implant failure due to rapid degradation, which triggers the release of harmful metal ions. In the present work, a passive layer was obtained on the AZ31-Mg alloy, and subsequently, a cerium oxide (CeO₂) coating was deposited through a chemical conversion treatment using 0.01 M CeO₂ as a precursor. Based on X-ray photoelectron spectroscopy, the calculated amount of Ce(IV) and Ce(III) present in AZ31-Mg(OH)₂/CeO₂ was 93.6% and 6.4%, respectively. AZ31-Mg(OH)₂/CeO₂ showed improved corrosion resistance compared with the bare sample. The in vitro assessment of MC3T3-E1 pre-osteoblast cell viability showed that AZ31-Mg(OH)₂/CeO₂ was biocompatible after incubation for 24 and 72 h. The results revealed that the CeO₂ coating confers greater electrochemical stability and biocompatibility properties, mostly due to the presence of Ce⁴⁺ ions. Full article

: An overview of the literature reveals that electrodeposition baths significantly influence deposited coatings’ morphology and properties. The present study investigates a sulphate-based bath in terms of the additive, pH, and temperature for the electrodeposition of Zn–Co alloys onto mild steel, achieving a nanocrystalline structure. The obtained results of the cyclic voltametric and SEM analyses revealed that sodium allowed the enhancement of cobalt electrocrystallisation (22.6 wt%) to homogenize further layers’ structure. However, the adjustment of pH allowed for the obtention of deposits with a refined structure containing only 5 wt% cobalt. Although an increase in room temperature resulted in deposit coatings with the same cobalt content, it notably produced a smoother structure. Subsequently, Zn–Co coatings were compared to pure zinc layers in terms of micromechanical and tribological behaviour. The morphology shifted from hexagonal platelets to nodular structures with the incorporation of cobalt, leading to an increase in microhardness. The morphology transformation, coupled with micromechanical reinforcement, contributed to the mitigation of friction and the improvement of the wear resistance of zinc layers through cobalt alloying. In fact, this improvement enhances the performance of zinc-coated applications in automotive and aerospace industries, particularly for standard assembly components that require adequate resistance to wear and abrasion during handling and tightening. Full article

Fuel cells/zinc–air cells represent a transformative technology for clean energy conversion, offering substantial environmental benefits and exceptional theoretical efficiency. However, the high cost and limited durability of platinum-based catalysts for the sluggish oxygen reduction reaction (ORR) at the cathode severely restrict their scalability and practical application. To address these critical challenges, this study explores a groundbreaking approach to developing ORR catalysts with enhanced performance and reduced costs. We present a novel Pd₃Cu alloy, innovatively modified with N-doped carbon aerogels, synthesized via a simple self-assembly and freeze-drying method. The three-dimensional carbon aerogel-based porous structures provide diffusion channels for oxygen molecules, excellent electrical conductivity, and abundant ORR reaction sites. The Pd₃Cu@2NC-20% aerogel exhibits a remarkable enhancement in ORR activity, achieving a half-wave potential of 0.925 V, a limiting current density of 6.12 mA/cm², and excellent long-term stability. Density functional theory (DFT) calculations reveal that electrons tend to transfer from the Pd atoms to the neighboring *O, leading to an increase in the negative charge around the *O. This, in turn, weakens the interaction between the catalyst surface and the *O and optimizes the elementary steps of the ORR process. Full article

(1) In recent years, an increase in the available functionality of non-ferrous alloys has been observed based on the modification and optimization of their chemical composition. This study investigated the effect of Sr addition on the structure and properties of hypereutectic Zn–Al–Cu alloys. The objective was to determine how a modification with Al–Sr master alloy affects the crystallization kinetics, microstructure, hardness, and abrasive wear resistance and whether the modification of the phase composition reduces the corrosion resistance. (2) The total influence of strontium was determined based on the microstructure, phase composition, and derivative curve changes of the tested Zn–Al–Cu alloys with added Sr. Optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to analyze the influence of chemical and phase composition, and thermo-derivative analysis (TDA) was used to investigate the crystallization kinetics of zinc alloys with different chemical compositions. (3) Sr modification caused the formation of primary Al₂Sr phases in the Zn alloy and also secondary Zn₁₃Sr and Al₄Sr phases (depending on the melting temperature of the alloy). (4) The primary and secondary intermetallic phases with strontium increased the hardness by approx. 20% and the abrasion resistance by approx. 7.5%. Full article

The rising prevalence of orthopedic conditions, driven by an aging population, has led to a growing demand for advanced implant materials. Traditional metals such as stainless steel and titanium alloys are biologically inert and often necessitate secondary surgical removal, imposing both economic and psychological burdens on patients. Biodegradable zinc-based alloys offer promising alternatives due to their moderate degradation rates, biocompatibility, and tissue-healing properties. However, existing studies on Zn-Fe alloys primarily focus on composition optimization, with limited investigation into how processing methods influence their performance. This study explores the effects of rotary forging on the microstructure and mechanical properties of Zn-0.5Fe alloys. By refining grain structure and promoting dynamic recrystallization, rotary forging achieves significant improvements in ductility (60% elongation, a 114% increase compared to the extruded state) while maintaining corrosion resistance. Electrochemical and immersion tests reveal that rotary forging produces a denser and more protective corrosion layer, thereby improving the degradation performance of the material in simulated body fluid. Cytotoxicity and fluorescence staining tests confirm excellent biocompatibility, validating the material’s suitability for medical applications. These findings elucidate the mechanisms by which rotary forging enhances the properties of Zn-0.5Fe alloys, providing a novel approach to tailoring biodegradable implant materials for orthopedic applications. Full article

Carbon dioxide (CO₂) can be electrochemically, thermally, and photochemically reduced into valuable products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH₄), and methanol (CH₃OH), contributing to carbon footprint mitigation. Extensive research has focused on catalysts, combining experimental approaches with computational quantum mechanics to elucidate reaction mechanisms. Although computational studies face challenges due to a lack of accurate approximations, they offer valuable insights and assist in selecting suitable catalysts for specific applications. This study investigates the electrocatalytic pathways of CO₂ reduction on cuprous oxide (Cu₂O) catalysts, utilizing the computational hydrogen electrode (CHE) model based on density functional theory (DFT). The electrocatalytic performance of flat Cu₂O (100) and hexagonal Cu₂O (111) surfaces was systematically analysed, using the standard hydrogen electrode (SHE) as a reference. Key parameters, including free energy changes (ΔG), adsorption energies (E_ads), reaction mechanisms, and pathways for various intermediates were estimated. The results showed that CO₂ was reduced to CO_(g) on both Cu₂O surfaces at low energies. However, methanol (CH₃OH) production was observed preferentially on Cu₂O (111) at ΔG = −1.61 eV, whereas formic acid (HCOOH) and formaldehyde (HCOH) formation were thermodynamically unfavourable at interfacial sites. The CO₂-to-methanol conversion on Cu₂O (100) exhibited a total ΔG of −3.38 eV, indicating lower feasibility compared to Cu₂O (111) with ΔG = −5.51 eV. These findings, which are entirely based on a computational approach, highlight the superior catalytic efficiency of Cu₂O (111) for methanol synthesis. This approach also holds the potential for assessing the catalytic performance of other transition metal oxides (e.g., nickel oxide, cobalt oxide, zinc oxide, and molybdenum oxide) and their modified forms through doping or alloying with various elements. Full article

The application of deep eutectic solvents (DESs) as an innovative class of environmentally friendly liquid media represents a significant advancement in materials science, especially for the development and enhancement of structural materials. Among the promising applications, DESs are particularly attractive for the electrodeposition of corrosion-resistant coatings. It is established that corrosion-resistant and protective coatings, including those based on metals, alloys, and composite materials, can be synthesized using both traditional aqueous electrolytes and non-aqueous systems, such as organic solvents and ionic liquids. The integration of DESs in electroplating introduces a unique capacity for precise control over microstructure, chemical composition, and morphology, thereby improving the electrochemical corrosion resistance and protective performance of coatings. This review focuses on the electrodeposition of corrosion-resistant and protective coatings from DES-based electrolytes, emphasizing their environmental, technological, and economic benefits relative to traditional aqueous and organic solvent systems. Detailed descriptions are provided for the electrodeposition processes of coatings based on zinc, nickel, and chromium from DES-based baths. The corrosion–electrochemical behavior and protective characteristics of the resulting coatings are thoroughly analyzed, highlighting the potential and future directions for developing anti-corrosion and protective coatings using DES-assisted electroplating techniques. Full article

The mechanical and hydrodynamic characteristics of single-piece nets are key to the design and optimization of offshore aquaculture net cages. A numerical approach for offshore submerged aquaculture net materials based on the Morison equations and finite element is proposed, simulating the hydrodynamic characteristics of single-piece nets under varying parameters such as wire diameter, mesh size, and flow velocity, and simulating the impact of marine organism attachment on nets by modifying the drag coefficient. The simulation results of nets made from materials such as Copper–Zinc Alloy (Cu-Zn), Zinc–Aluminum Alloy (Zn-Al), Semi-Rigid Polyethylene Terephthalate (PET), and Ultra-High Molecular Weight Polyethylene (UHMWPE) are compared, which provides a theoretical basis for optimizing design parameters and selecting materials for nets based on force conditions and hydrodynamic characteristics. The simulation results indicate that the current force on the net is positively correlated with flow velocity; the maximum displacement of the net is also positively correlated with the flow rate. Compared to other materials, the Cu-Zn net is subjected to the greatest water flow force, while the UHMWPE net experiences the greatest displacement; the larger the diameter of the netting twine, the greater the current force on the net; the mesh size is inversely related to the current force on the net. With increasing drag coefficient, both the maximum displacement of the net and the current force experiences increase, and UHMWPE material nets are more sensitive to increases in the drag coefficient, which indicates a greater impact from the attachment of marine organisms. The density and elastic modulus of the netting material affect the rate of increase in force on the net. The research results can provide a basis for further research on material selection and design of deep-sea aquaculture nets. Full article

Infections continue to pose significant challenges in dentistry, necessitating the development of innovative solutions that can effectively address these issues. This study focuses on creating coatings made from polymethyl methacrylate (PMMA) enriched with zinc oxide–silver composite nanoparticles, layered to Ti6Al4V–titanium alloy substrates. The application of these materials aims to create a solution for the abutments utilized in complete dental implant systems, representing the area most susceptible to bacterial infections. The nanoparticles were synthesized using a hydrothermal method, optimized through specific temperature and pressure parameters to achieve effective morphologies and sizes that enhance antibacterial efficacy. The layers were applied to the titanium substrate using the spin coating technique, chosen for its advantages and compatibility with the materials involved. Comprehensive analyses were conducted on the antimicrobial powders, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Furthermore, the PMMA-based coatings incorporating antimicrobial nanoparticles were evaluated to ensure uniformity and homogeneity across the titanium alloy surface by IR mapping and SBF immersion–SEM analysis. The antimicrobial activity of the samples was demonstrated with impressive results against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, as assessed through biofilm modulation studies. The biocompatibility of the samples was validated through in vitro cell-based assays, which demonstrated excellent compatibility between PMMA-based coatings and human preosteoblasts, confirming their potential suitability for future use in dental implants. Full article

Kesterite-based semiconductors, particularly copper–zinc–tin–sulfide (CZTS), have garnered considerable attention as potential absorber layers in thin-film solar cells because of their abundance, nontoxicity, and cost-effectiveness. In this study, we explored the synthesis of Ag-alloyed CZTS (ACZTS) materials via the sol–gel method and deposited them on a transparent fluorine-doped tin oxide (FTO) back electrode. A key challenge is the selection and manipulation of metal–salt precursors, with a particular focus on the oxidation states of copper (Cu) and tin (Sn) ions. Two distinct protocols, varying the oxidation states of the Cu and Sn ions, were employed to synthesize the ACZTS materials. The transfer from the solution to the precursor film was analyzed, followed by annealing at different temperatures under a sulfur atmosphere to investigate the behavior and growth of these materials during the final stage of annealing. Our results show that the precursor transformation from solution to film is highly sensitive to the oxidation states of these metal ions, significantly influencing the chemical reactions during sol–gel synthesis and subsequent annealing. Furthermore, the formation pathway of the kesterite phase at elevated temperatures differs between the two protocols. Structural, morphological, and optical properties were characterized via X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Our findings highlight the critical role of the Cu and Sn oxidation states in the formation of high-quality kesterite materials. Additionally, we studied a novel approach for controlling the synthesis and phase evolution of kesterite materials via molecular inks, which could provide new opportunities for enhancing the efficiency of thin-film solar cells. Full article