Search Results (444)

The use of bulk heat treatments to improve the resistance of the material structures to cavitation erosion remains an effective approach due to the beneficial modifications induced in the microstructure and physical-mechanical properties. Depending on the intensity of cavitation loading, various heat treatment regimes can be applied. Among these, artificial aging treatments are particularly suitable for non-ferrous alloys, especially aluminum, zinc, and magnesium-based alloys. The current study investigates the effect of artificial aging heat treatment performed at 250 °C with holding times of 12 and 24 h on the biodegradable magnesium-based AM50 alloy. Cavitation tests were carried out using the method with a stationary specimen on a standard vibratory device according to ASTM G32-2016 requirements. The analysis of cavitation-eroded surfaces through macro- and microstructural images, together with the interpretation of characteristic erosion curves and specific parameters (cumulative mass loss, erosion speed and cavitation resistance), revealed both similarities and significant differences governed primarily by surface hardness and microstructural features. Comparison with the initial (semi-finished) state and with previous studies on artificial aging treatments performed at 200 °C for 12 and 24 h confirms the similarly beneficial effect of the 250 °C aging regime on the cavitation erosion resistance of the AM50 alloy. Full article

Hopeite (Zn₃(PO₄)₂·4H₂O) coatings, obtained via zinc phosphate chemical conversion (ZPCC), have gained increasing attention in the biomedical field. Such coatings are particularly appealing owing to their combined capability of excellent corrosion resistance and biocompatibility. This study investigates the influence of processing time on the formation of hopeite coatings on AZ91D magnesium alloy by zinc phosphate chemical conversion (ZPCC). X-ray diffraction (XRD) analysis confirmed that the coatings primarily consisted of hopeite, with trace amounts of phosphophyllite. The maximum coating mass and thickness were achieved after a 30 min treatment at 55 °C. Electrochemical measurements demonstrated superior corrosion resistance for coatings formed within 15–30 min. Additionally, coating self-adhesion tests revealed strong bonding between the coating and the substrate. Full article

Methods for the preparation of aluminum hydroxides and alumina-supported catalysts through the interaction of activated Al–In–Ga alloys with water were developed. Bayerite was obtained from an alloy containing 99.0% Al + 0.5% In + 0.5% Ga at 303 K, while pseudoboehmite was synthesized from 90% Al + 5% In + 5% Ga at 363 K. The maximum specific surface area of aluminum oxide reached 700 m²/g. Dehydration of aluminum hydroxides proceeds via a sigmoidal mechanism with induction, acceleration, and deceleration stages. The dehydration rate increases with calcination temperature. Kinetic analysis revealed both kinetic and diffusion-controlled transformation regions for pseudoboehmite and bayerite. Transformation of pseudoboehmite into γ-Al₂O₃ at 523–673 K preserves a high specific surface area of 630–640 m²/g. Two platinum deposition methods were proposed: synthesis in the presence of soluble platinum salts and incorporation of Pt into the Al–Ga–In alloy followed by reaction with water. Alongside metallic Pt, Ptδ⁺, Pt²⁺, and Pt⁴⁺ species were detected and reduced to Pt⁰ at 900 K. Alumina–platinum catalysts showed high activity in cyclohexane dehydrogenation. A Zn–Al catalyst for methanol decomposition was developed, providing up to 70% H₂ in gaseous fuel and complete methanol conversion at 573 K. Full article

To address the uneven deposition of zirconium conversion coatings on multiphase 55AlZnMg under short pretreatment cycles, this study investigated the time-dependent formation behavior of ZrCC in a selected H₂ZrF₆ bath. By precisely controlling the immersion time (20–90 s) and utilizing SEM-EDS and AFM characterization techniques, this study systematically revealed the growth kinetics and film-forming mechanisms of ZrCC on complex alloy surfaces. The results indicate that the Zn-rich phase on the surface of the 55AlZnMg coating, due to its relatively positive potential, preferentially induces the deposition of the film-forming material. Subsequently, dealloying occurs in the Al-rich phase and the Mg/Zn enriched regions, forming Zn-enriched regions that promote the continuous deposition of the film-forming material, ultimately achieving complete surface coverage; the film morphology evolves from an initial needle-like structure to a network structure, eventually forming a nanosheet structure. The film-forming process of ZrCC on the 55AlZnMg substrate surface is primarily driven by selective growth, with electrochemical properties of the alloy phases, significantly enhancing adhesion between the aluminum-zinc-magnesium coating and the overcoat and providing practical guidance for improving surface uniformity and interfacial adhesion of Al-Zn-Mg-coated steel. Full article

This study addresses the issue of insufficient product purity caused by the co-deposition of three major impurity ions—zinc, nickel, and lead—during the electrodeposition process of high-purity manganese. A targeted deep purification method for manganese sulfate electrolyte was developed using dithiocarbamate chelating agents (sodium dimethyldithiocarbamate, SDD). By optimizing key process parameters such as precipitant concentration, reaction temperature, reaction time, and solution pH, combined with density functional theory (DFT) calculations, to elucidate the selective impurity removal mechanism at the molecular level, a novel process for the efficient synergistic removal of Zn²⁺, Ni²⁺, and Pb²⁺ was established. The results showed that under the conditions of precipitant concentration of 1 g/L, solution pH of 6.5, reaction temperature of 55 °C, and reaction time of 2 h, the residual concentrations of Zn, Ni, and Pb in the electrolyte were all below 0.2 mg/L. DFT calculations revealed that SDD coordinates with metal ions through four sulfur atoms, and the absolute values of binding energies follow the order Ni²⁺ > Pb²⁺ > Zn²⁺ > Mn²⁺, indicating thermodynamically preferential capture of impurity ions. After purification, the manganese metal obtained by electrodeposition from the manganese sulfate solution achieved a purity exceeding 99.999%, with Zn, Ni, and Pb contents of 0.11 mg/kg, 0.038 mg/kg, and 0.05 mg/kg, respectively, meeting the raw material requirements for semiconductor-grade copper–manganese alloy targets. Full article

Composite materials with Ti or Ti alloy reinforcement in a Zn matrix are new, promising materials with potential applications in implantology. Infiltrating zinc into the porous titanium reinforcement of a designed implant could improve its osseointegration. In this field, it is important to avoid the formation of brittle intermetallics; therefore, understanding their growth is fundamental. This work focuses on characterizing the Ti-Zn intermetallic phases at the interface of the TiAlV/Zn and Ti/Zn composites. Samples were prepared by immersing the Ti-6Al-4V or Ti bulk material in zinc melt at various temperatures. After various dwell times, the samples (pieces of Ti-6Al-4V or Ti in the molten zinc) were removed from the furnace and cooled in air. The sequence of evolution of intermetallic phases was observed to be dependent on dwell time at selected temperatures. The influences of surface treatment methods on the boundary structure were also tested. Full article

Illyrian helmets represent a key element of Iron Age martial culture in the western Balkans, reflecting technological knowledge, workshop traditions, and long-distance cultural exchange. Based on the currently available archaeological record, Illyrian helmets are first attested in contexts dating to the 8th–7th centuries BC, with finds concentrated in Greece and the central and western Balkans, including Macedonia, Albania, Dalmatia, and the wider interior. Over time, the form developed into several variants (Types I–IIIB). This study presents the elemental characterization of the total set of 27 Illyrian helmets excavated in Albania and currently preserved in local museum collections, a region where the later types are particularly well attested. As the helmets are intact and exhibited in museums, portable in situ XRF analysis was employed. The main research questions addressed how the alloy composition, including minor and trace elements, reflects local metallurgical practices and distinguishes Illyrian helmets from similar helmets in neighboring regions. The results indicate the consistent use of bronze alloys dominated by copper (89–95%) with low- to medium-tin contents (3.5–9.9%), consistent with established alloying practices for durable protective equipment. Minor and trace elements, including iron (up to 1.5%), lead (up to 0.76%), arsenic (up to 0.09%), zinc (up to 1.17%), and antimony (up to 2.36%), likely reflect metallurgical choices, recycling practices, or impurities linked to regional copper deposits. Principal Component Analysis of four retained components, collectively accounting for 88.5% of the total variance, confirms a broadly standardized bronze tradition, with compositional outliers suggesting locally variable ore sources or recycling rather than systematic typological change. These elemental signatures, particularly the association of arsenic, antimony, zinc, and iron, suggest regional metallurgical characteristics consistent with Albanian sulphide ore deposits, while the overall compositional homogeneity supports the hypothesis of centralized production at workshops such as Epidamnus and Apollonia. Full article

Copper (Cu) smelting slags are considered secondary reserves of technology metals (TMs) and base metals (BMs), which are crucial for the transition to renewable energy and mechatronic applications. In this study, thermochemical and experimental analyses were conducted to investigate the pyrometallurgical extraction of TMs and BMs from Cu smelting slag. FactSage thermochemical simulations and smelting experiments were carried out at temperatures from 1300 to 1600 °C and with carbon (reductant) additions of 2% to 10% relative to the mass of the feed slag. The results showed that during smelting, gallium (Ga), germanium (Ge), cobalt (Co), and copper (Cu) deported into the iron-based alloy product. Zinc (Zn) and lead (Pb) oxidised to ZnO and PbO, respectively, which were subsequently collected as fumes. The produced alloy mass was more sensitive to carbon addition than to smelting temperature variation. The TM and BM contents in the alloy decreased with increasing carbon addition in the feed; this was attributed to dilution by Fe, Si, and C from the increasing reduction of iron and silicon oxides in the feed slag and dissolution of C in the alloy. High recovery degrees of TMs and BMs in the alloy stream—over 90% for Co and Cu, over 50% for Ga, and over 70% for Ge—were achieved when smelting at 1500 °C with 4% carbon addition. The final alloy comprised 70.5% Fe, 6.6% Co, 23.6% Cu, 0.11% Ga, and 0.13% Ge. The fumes primarily comprised ZnO and, to a lesser extent, PbO, with recovery degrees over 90% for Zn and Pb. These alloy and fume products would be processed following conventional hydrometallurgical separation and purification processes to produce high-purity metals. The pyrometallurgical extraction of TMs and BMs presents an opportunity for the valorisation of Cu smelting slag dumps, especially in Southern Africa, aiming to attain zero-waste industrial processes. Full article

Stricter drinking water regulations intensify the need to replace leaded brasses in fittings. This work reports preliminary results on internally coated fittings using the wrought zinc alloy ZnAl15Cu1Mg (ZEP1510). A straight-tube Model Geometry 1 was lined internally with HDPE by gas-assisted injection molding, achieving a continuous barrier of 1.55–1.70 mm without altering the external envelope. A press-type T-fitting (32–32–32) was defined as Model Geometry 2 to benchmark forgeability; process layout (FEM) and warm-forging trials are summarized. Recycling relevance was addressed via a partial-melt (drip-off) route, which removed a substantial polymer fraction but left measurable residues. A production-cycle PCF from material production to finished tee indicates 3.156 kg CO₂e for ZEP1510 vs. 5.385 kg CO₂e (CuZn40Pb2) and 6.301 kg CO₂e (CuZn21Si3), i.e., 41.85% and 50.06% savings. These findings establish manufacturability, indicate recycling feasibility, and quantify a CO₂ advantage, outlining the next steps toward lining complex geometries and drinking water compliance. Full article

Copper-based hybrid metal matrix composites reinforced with graphene and zinc were developed to achieve a balanced combination of mechanical strength, corrosion resistance, wear performance, and electrical conductivity. In this study, Cu matrix composites containing a constant graphene content of 1 wt.% and varying Zn contents (0, 5, 10, and 15 wt.%) were fabricated through mechanical alloying followed by Spark Plasma Sintering (SPS). The effects of zinc content on microstructure, densification, hardness, corrosion behavior, tribological performance, and electrical conductivity were systematically investigated. Microstructural analyses revealed that the combined use of graphene and Zn significantly influenced grain refinement, interfacial stability, and densification behavior. The composite containing 10 wt.% Zn exhibited the highest relative density (~90.5%) and maximum hardness (62 HB), indicating an optimal reinforcement level. Corrosion tests conducted in 3.5 wt.% NaCl solution demonstrated that the 10 wt.% Zn composite showed the most noble corrosion potential and the lowest corrosion current density, which was attributed to reduced porosity and improved microstructural homogeneity. Tribological results confirmed that graphene contributed to a self-lubricating effect, while Zn enhanced load-bearing capacity, leading to improved wear resistance under increasing normal loads. Electrical conductivity measurements showed a gradual decrease with increasing Zn content, mainly due to solid-solution-induced electron scattering in the Cu matrix; however, the fixed graphene addition and effective SPS consolidation helped preserve conductive pathways, allowing all composites to retain acceptable conductivity levels. The results indicate that the hybrid Cu–graphene–Zn composites exhibit a balanced combination of mechanical, corrosion, tribological, and electrical properties, with 10 wt.% Zn emerging as the optimal composition. Full article

Biodegradable zinc (Zn) has attracted increasing interest as a material for temporary implants, primarily due to its moderate degradation kinetics. In recent years, additive manufacturing of Zn alloys using the laser powder bed fusion method (L-PBF) has shown promising results. Compared to as-cast Zn alloys, it offers preferable customized solutions for patient-specific temporary biomedical implants. Due to the novelty of these printed degradable biomaterials and due to reported cytotoxic effects of Zn alloys, this study investigates additively manufactured ZnAgCu, ZnAgCuMn, and ZnAgCuTi alloys, both in as-printed and post-processed conditions, with a focus on L929 and SAOS-2 biocompatibility. In this work, we demonstrate that the increased porosity and therefore larger surface areas compared to polished Zn-alloy samples affect their biocompatibility. Minimal to no cell proliferation was observed on and near the Zn-alloy test plates after 24 h. Undiluted extracts from as-cast Zn and L-PBF-manufactured plates were initially cytotoxic to SAOS-2 cells. However, as passivation proceeded, cytocompatibility was significantly increased from day 3 onward. Zn²⁺ ion release peaked at 24 h and declined significantly from day 2 to day 10. Compared to the other Zn alloys, ZnAgCuMn exhibited the lowest cytocompatibility. Most intriguingly, 3-month surfaces exhibited reduced cytocompatibility to osteoblasts compared to freshly polished samples. The observed in vitro cytotoxicity motivates further investigation of as-printed and post-processed L-PBF-manufactured Zn alloys, aiming to develop novel surface modification strategies to mitigate the initial ion burst responsible for reduced cytocompatibility and to adjust and tailor the overall degradation kinetics to physiologically tolerable levels tailored to the intended clinical application. Full article

Surface damage occurring during surgery can compromise coating integrity, leaving exposed areas susceptible to bacterial colonization. However, the impact of partial coating loss on antibacterial performance has not yet been investigated. In this work, a multifunctional UV-activated coating composed of hydroxyapatite, magnesium phosphate, and zinc oxide (HMZ) was developed and electrodeposited onto AZ31 and MgCa magnesium alloys. Its antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated under three conditions: adhered bacteria, planktonic cells, and biofilm. In the absence of UV activation, coated surfaces exhibited no significant antibacterial activity. In contrast, fully coated and UV-activated surfaces achieved bacterial reductions above 98% in all scenarios. Surfaces with 60% coverage showed antibacterial efficacy equivalent to that of fully coated surfaces, even against established biofilm. Surfaces with 30% coverage also exhibited moderate activity, particularly against adhered and planktonic bacteria. These results demonstrate that full surface coverage is not required to preserve the coating’s antibacterial effectiveness. This strategy provides a clinically relevant solution to maintain antibacterial protection even when coating integrity is compromised. Full article

This study focused on investigating the influence of zinc on tin pest, both alone and in combination with lead and copper. Based on the known composition of the organ pipe from Trpín, five model alloys were prepared, from which model samples were produced. The model alloys were exposed to low temperatures for 100 days or until complete degradation occurred. The kinetics of the transformation were compared for annealed and non-annealed samples. It was confirmed that the transformation is much faster in samples with retained internal stress. A comparison of the Avrami coefficients indicated similar nucleation behavior for both sample types. Phase transformation was observed in samples containing tin, copper, zinc, and lead, as well as those containing only copper and lead. This suggests that even a relatively small amount of zinc (0.25 wt.%) and copper (0.9 wt.%) can affect the course of tin pest in an alloy containing 13 wt.% lead. Transformation progressed more slowly in samples with only 0.25 wt.% zinc than in pure tin, likely due to the limited solubility of zinc in a tin with low concentrations of alloying elements. The crystallographic structure of both the model alloys and the original historical pipe material was studied using transmission electron microscopy (TEM). In almost all model samples, zinc was uniformly dissolved in the tin matrix. However, in the original pipe, zinc was primarily located at grain boundaries and in association with copper. This indicates that zinc was not intentionally added to the historical alloy but likely appeared in the alloy as a contaminant of impure copper. Full article

Rechargeable zinc–air batteries (ZABs) are still impeded by the intrinsically sluggish kinetics of oxygen reduction and evolution reactions (ORR/OER) and by the instability or prohibitive price of state-of-the-art noble metal catalysts. Metal–organic frameworks (MOFs) have recently emerged as versatile sacrificial templates for next-generation air–cathode electrocatalysts. By programming pyrolytic or chemical conversion pathways, MOFs can be quantitatively transformed into hierarchically porous, heteroatom-doped carbon scaffolds that embed uniform metal, alloy, or metal-oxide nanodomains. The resulting architectures couple metallic conductivity with molecular-scale active site tunability, delivering exceptional ORR/OER activity, stability, and mass transport properties. This review critically examines the most recent advances in MOF-derived electrocatalysts for ZABs, establishing quantitative structure–composition–performance relationships across mono-, bi-, and multi-metallic systems. Emphasis is placed on deciphering how framework topology, metal–ligand coordination, and post-synthetic parameters dictate the density, electronic structure, and accessibility of surface-active moieties during catalyst evolution. We further dissect engineering strategies that enhance intrinsic activity via electronic modulation, bolster durability through encapsulation effects, and optimize hierarchical porosity for rapid O₂/water transport. This article concludes by outlining unresolved challenges and future research directions, including atomically precise active site construction, multi-scale compositional control, long-term reversibility under realistic ZABs cycles, scalable and green synthesis, providing a roadmap for translating MOF-derived catalysts from laboratory curiosities to commercially viable air–cathode materials. Full article

Ag and Cu in biodegradable Zn alloys have been the focus of research due to their biocompatible corrosion products, as well as their ability to improve the mechanical properties of the alloy. In this research, the impact of Ag and Cu on the fluidity of biodegradable Zn alloys was evaluated through the spiral fluidity test. Zn–xAg and Zn–xCu alloys containing Ag or Cu in pure Zn at proportions of 0.5, 1, 2, and 3 wt.% were prepared. In the first stage of the study, the casting temperature to be used in the fluidity tests of the alloys was determined by casting pure Zn at different temperatures. Spiral castings of the alloys were then produced and the fluidity lengths in the spiral channel were measured. Test results showed that the mold filling distances decreased with increasing amounts of Ag and Cu, with Cu causing a stronger reduction than Ag at comparable addition levels. When the Ag content in Zn was raised from 0.5 wt.% to 1 wt.%, a significant reduction in fluidity was observed. Formation of CuZn₅ and ε–AgZn₃ phases in the microstructures was identified as the main factor limiting melt flow. These findings provide insights into how Ag and Cu additions influence the castability of Zn alloys, offering guidance for optimizing alloy composition for biodegradable implant applications. Full article