ECO-AZ31 magnesium alloy modified with 1 wt.% CaO, was investigated for the production of thinwalled tubes by Friction Stir Extrusion (FSE), employing recycled chips through solid-state consolidation. The study focused on the influence of tool rotational speed, ranging from 500 to 1000 rpm, on the consolidation quality, microstructure and mechanical properties of the extruded tubes. The results indicate that low rotational speeds lead to poor material consolidation and surface defects due to insufficient heat generation, whereas high rotational speeds caused overheating and excessive grain growth. In contrast, intermediate rotational speeds were found to be optimal, as they resulted in defect-free tubes with a wall thickness of ~500 μm, exhibiting a refined microstructure (achieving grain sizes in the range of 5–7 μm in the inner region) and improved microhardness (with values close to 80 HV). Microstructural analysis revealed a heterogeneous microstructure throughout the tube wall thickness, associated with the thermal and deformation gradients. At intermediate rotational speeds, {10 1 2} tensile twinning was activated as the dominant mechanism of deformation accommodation, partially reducing dislocation accumulation and softening the texture, leading to a localized decrease in hardness despite the refined grain size. These results demonstrate that the combined effect of heat generation, plastic deformation, dynamic recrystallisation, and twinning determines the final tube properties, confirming FSE as a sustainable and energy-efficient route for producing thin-walled tubes from recycled machining chips.
Copper–graphene nanoplatelet (Cu–GNP) composite coatings were electrodeposited onto nickelplated steel substrates using direct current (DC) and pulse reverse current (PRC) techniques. The influence of the deposition regime on microstructure, nanoplatelet incorporation, and mechanical performance was investigated. Optical microscopy revealed that PRC deposition produced more homogeneous and refined microstructures compared to DC deposition. Raman spectroscopy confirmed the successful incorporation of graphene nanoplatelets within the copper matrix. Microhardness measurements showed a significant improvement in mechanical performance, with PRC coatings reaching an increase of 69.7% compared to DCdeposited coatings. The enhanced hardness is attributed to grain refinement, improved nanoplatelet dispersion, and effective dispersion strengthening mechanisms activated under pulse reverse conditions.
This study investigates the valorization of zinc electrolysis residues generated at the Trepça industrial facilities for their potential application in cement clinker production at the Sharrcem plant. These residues have been stockpiled for nearly 30 years in open environments, posing significant environmental and health risks. Chemical characterization was performed using a VITRIOX ELECTRIC furnace applying the fused-bead method, revealing a high iron oxide content (Fe₂O₃, 80.20 wt%) along with SiO₂, Al₂O₃, CaO, MgO, K₂O, Na₂O, and SO₃. The elevated Fe₂O₃ content plays a critical role in clinker mineralogy by promoting the formation of calcium ferrites (C₄AF), which influence burnability and phase stability. Phase equilibria and thermodynamic simulations conducted using the CALPHAD approach identified dominant phases such as BCC_A2, FCC_A1, DIAMOND_FCC_ A4, and IONIC_LIQ, with phase stability strongly dependent on temperature and silicon content. The results demonstrate that zinc electrolysis residues can be effectively integrated into clinker production, improving material efficiency while reducing the consumption of virgin raw materials. This approach offers a sustainable solution for industrial waste management and contributes to environmental protection and circular economy practices.
The present work aims to analyze the mechanical behaviour of laser-welded Inconel 825 and AISI 410 welded joints. The main goal of this study is to assess the Vickers microhardness, tensile properties, and metallurgical features (using SEM and EDAX) of welded joints under different operating conditions. In Laser Surface Modification, laser welding was performed at 1200 W to 1800 W, with a welding speed of 30 mm s-1 and a laser head focal distance of 200 mm. The gap between the materials during welding was 0.05-0.2 mm. The mechanical properties of the welds were assessed using Vickers microhardness testing and tensile testing. The microstructural examination and element analysis of the welded joints were performed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The mechanical and microstructural integrity of the joints as a function of laser power, welding speed, and gap distance is discussed. It provides an important reference for optimizing laser welding technology for similar-metal welds in high-strength, high-temperature dissimilar-metal joints.
This study provides a comprehensive examination of how corrosion impacts the structure-property relationships of P110 and N80 carbon steels, which are widely utilized for tubing and casing in the oil and gas industry. A multi-technique approach was employed, including optical microscopy, X-ray fluorescence, Vickers hardness testing, and confocal microscopy, to analyze samples in both their as-received and corroded states. The results reveal that corrosion significantly degrades the microstructure and mechanical properties of both steels. P110 steel, characterized by a tempered martensite microstructure and higher initial strength, exhibits severe localized pitting corrosion and a substantial increase in surface roughness. In contrast, N80 steel shows more uniform and diffuse degradation with significant surface oxide growth. Corrosion induces a notable reduction in hardness and a non-linear evolution of deformation under load, highlighting the complex interplay between microstructure and environmental degradation. The innovative contribution of this work lies in the development of a predictive framework that links these experimental observations to material service life. This framework provides a valuable tool for the oil and gas industry, enabling a shift from reactive maintenance to proactive asset management, thereby enhancing operational safety and economic efficiency.
This study examines systematic microstructural evolution, mechanical behavior and corrosion resistance of Mg-4Al-X1Ca-X2Zn-0.4Mn alloys, where calcium (Ca), X1 = 0.5 and 0.8, and zinc (Zn), X2 = 0.8 and 1.2 wt.%. The three alloys were fabricated by gravity die casting, thereafter, undergoing homogenization and hot rolling. Their characterization was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDX). The characterization process included pole figure analysis, hardness evaluation, tensile and immersion corrosion tests. Microstructural and XRD analysis indicated that a primary alpha-Mg matrix with Mg17Al12, Al2Ca, Ca(Al1.34, Mg0.66), and Al8Mn5 intermetallic phases. AZXM4110B alloy, containing highest Ca and Zn, achieved the best balance of strength and ductility. The YS and UTS values of this alloy reached 155.8 MPa and 256.6 MPa in the rolling direction (RD) with 8.7% fracture strain. The hardness tests indicated that AZXM4110B alloy had also the lowest value, with an average of 61.0 HV. The corrosion resistance in the 3.5% NaCl solution indicated AZXM4110A alloy with the highest Zn content showed the lowest corrosion rates of 25.8, 11.4, and 15.4 mm/year, respectively, at 24, 72, and 120 hours.
Contemporary pyrometallurgy faces the pressing challenge of supplying critical metals for the energy transition. Within this context, the flash smelting furnace, conceived in Finland in 1949, has emerged as a paradigmatic process due to its exothermic nature and its capacity to transform pollutants into valuable resources. Responsible for nearly 50% of global copper production, the furnace operates by injecting dry concentrates with oxygen, achieving temperatures above 1200 degrees C and enabling the capture of sulfur dioxide for conversion into sulfuric acid, a high-value industrial by-product. Yet, the circularity of the process is conditioned by mineralogical constraints and the origin of concentrates: Chile contends with arsenic volatilization in enargite, Spain with variability in imported feedstocks, Finland with the adaptation to Cu-Ni mixtures, while China and Japan grapple with large-scale operations and penalties for impurities. This critical literature review integrates technical foundations, comparative international cases, and digital innovation strategies for emissions control and impurity management. The findings underscore that the flash furnace is not merely a metallurgical device but exemplifies industrial resilience and circularity, advancing pyrometallurgy toward an ethical, efficient, and sustainable future.
La pirometalurgia contemporánea enfrenta el desafío urgente de proveer metales críticos para la transición energética. En este contexto, el horno flash, concebido en Finlandia en 1949, se ha consolidado como un proceso paradigmático por su carácter exotérmico y su capacidad de transformar contaminantes en recursos de alto valor. Responsable de cerca del 50 % de la producción mundial de cobre, este sistema inyecta concentrados secos con oxígeno, alcanzando temperaturas superiores a 1200 °C y permitiendo la captura del dióxido de azufre para su conversión en ácido sulfúrico, un subproducto industrial estratégico. Sin embargo, la circularidad del proceso está condicionada por las limitaciones mineralógicas y el origen de los concentrados: Chile enfrenta la volatilización de arsénico en la enargita, España la variabilidad de las importaciones, Finlandia la adaptación a mezclas Cu–Ni, mientras que China y Japón lidian con la escala global y las penalizaciones por impurezas. Esta revisión crítica de la literatura integra fundamentos técnicos, casos internacionales comparativos y estrategias de innovación digital para el control de emisiones y la gestión de impurezas. Los hallazgos subrayan que el horno flash no es únicamente un dispositivo metalúrgico, sino que ejemplifica la resiliencia industrial y la circularidad, proyectando la pirometalurgia hacia un futuro ético, eficiente y sostenible.
The behaviour of a galvanised advanced high strength steel while being welded using wires and shielding atmospheres of different chemical compositions was studied. The analyses included metallographic examination and digital X-ray radiography to detect the porosity within the weld beads. Metallographic examination of welded samples revealed that the porosity was of the wormhole type. The results showed that porosity, attributed to vaporising of the zinc coating, increased as welding heat input augmented due to its effect on the solidification and cooling rates of the weld pool, allowing for a higher rate of zinc evaporation. Porosity was found to increase as the CO2 content in the shield gas was reduced, as well as the amount of silicon of the wires augmented, as both factors contribute to reduce the surface tension of the molten metal, which affects the shape of the Marangoni’s currents within the weld pool that will reduce the capacity of zinc fumes to escape from the weld pool.
Taking as a basis the composition of stainless steel rinse waters, the purification of nickel by the transport of Fe(III) and Cr(III) through a flat-sheet supported liquid membranes impregnated with DP8R (bis((2-ethylhexyl) phosphoric acid) in Exxsol D100 has been investigated. Different experimental variables affecting metals transport are considered: hydrodynamic conditions, and variations in the composition of the feed, carrier and stripping phases. Under optimal conditions (pH 3, 40% v/v DP8R), Fe(III) and Cr(III) are selectively removed, leaving purified nickel solutions.
Quasicrystals, first discovered in 1984 inAl-Mn alloys by Dan Shechtman, are non-periodically ordered phases that exhibit high hardness and low coefficients of friction, making them attractive for tribological applications. In this work, coatings were produced using High Velocity Oxygen-Fuel (HVOF) and Atmospheric Plasma Spray (APS) techniques, employing powders from the Al-Cu-Fe-B, Al-Cu-Fe-Cr, and Al-Co-Fe-Cr systems. Structural characterization was carried out by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). Porosity was determined through image analysis, and surface properties were evaluated via Vickers hardness, roughness, and sessile drop method for surface tension measurements. The relationship between surface work and toughness was analyzed, revealing a linear correlation between toughness and hardness. Results indicate that both the powder composition and the deposition technique influence the type and quantity of the quasicrystalline phases formed. HVOF coatings were found to be denser, with fewer defects and higher hardness.
The present study investigates the impact of cooling media on microstructure, wear and mechanical behaviour of as cast X210Cr12 tool steel which is frequently employed in cutting and shaping tools. Furnace, still oil and agitated oil bath cooling of X210Cr12 tool steels were employed to observe the effects on microstructural and structural characterization, wear behaviour, hardness and mechanical strength. Structural analysis revealed the presence of Cr3C2 and Cr7C3 carbide precipitates, alpha ferrite and austenite in varying amounts with respect to quenching conditions. The highest hardness value of 860 HV and the lowest coefficient of friction were obtained from quenching in agitated oil bath. The lowest tensile strength values were obtained by still oil bath, and a higher percentage of elongation occurred with agitated oil bath. It was concluded that quenching parameters are important in optimising the properties of X210Cr12 tool steel, offering potential for enhancements in microstructure and mechanical properties.
The objective of this study is to analyze the relationship between the concentrations of humic and fulvic acids and the bioavailability of heavy metals in the sediment of the Altoandino Collotacocha wetland. The analysis involved measuring the concentration of organic acids in the wetland and determining the metals in the sediment using Teyssier’s sequential extraction speciation and the UV spectroscopy method. The sediment results during the rainy season detected iron at high concentrations (5490.96 to 6533.83 mg·kg-1), aluminum at concentrations of (497.08 to 655.94 mg·kg-1), lead between 315.21 and 471.99 mg·kg-1, and arsenic between 55.85 and 91.26 mg·kg-1. The conclusions indicate that during the rainy season, the percentage composition of the wetland sediment at the eight stations showed that the percentage of humic acids is higher than that of fulvic acids. In the evaluations carried out on the speciation of metals in the sediment, it is therefore concluded that the bioavailability of heavy metals in the wetland is lower when the percentage of humic acids in the sediment is higher than that found in fulvic acid.
This study examines systematic microstructural evolution, mechanical behavior and corrosion resistance of Mg-4Al-X1Ca-X2Zn-0.4Mn alloys, where calcium (Ca), X1 = 0.5 and 0.8, and zinc (Zn), X2 = 0.8 and 1.2 wt.%. The three alloys were fabricated by gravity die casting, thereafter, undergoing homogenization and hot rolling. Their characterization was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDX). The characterization process included pole figure analysis, hardness evaluation, tensile and immersion corrosion tests. Microstructural and XRD analysis indicated that a primary α-Mg matrix with Mg17Al12, Al2Ca, Ca(Al1.34, Mg0.66), and Al8Mn5 intermetallic phases. AZXM4110B alloy, containing highest Ca and Zn, achieved the best balance of strength and ductility. The YS and UTS values of this alloy reached 155.8 MPa and 256.6 MPa in the rolling direction (RD) with 8.7% fracture strain. The hardness tests indicated that AZXM4110B alloy had also the lowest value, with an average of 61.0 HV. The corrosion resistance in the 3.5% NaCl solution indicated AZXM4110A alloy with the highest Zn content showed the lowest corrosion rates of 25.8, 11.4, and 15.4 mm/year, respectively, at 24, 72, and 120 hours.
Quasicrystals, first discovered in 1984 in Al-Mn alloys by Dan Shechtman, are non-periodically ordered phases that exhibit high hardness and low coefficients of friction, making them attractive for tribological applications. In this work, coatings were produced using High Velocity Oxygen -Fuel (HVOF) and Atmospheric Plasma Spray (APS) techniques, employing powders from the Al-Cu-Fe-B, Al-Cu-Fe-Cr, and Al-Co-Fe-Cr systems. Structural characterization was carried out by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). Porosity was determined through image analysis, and surface properties were evaluated via Vickers hardness, roughness, and sessile drop method for surface tension measurements. The relationship between surface work and toughness was analyzed, revealing a linear correlation between toughness and hardness. Results indicate that both the powder composition and the deposition technique influence the type and quantity of the quasicrystalline phases formed. HVOF coatings were found to be denser, with fewer defects and higher hardness.
This study compared the efficacy of Ultra-High Frequency Induction Sintering (UHFIS) against conventional furnace sintering for the production of pure aluminum Powder Metallurgy (PM) compacts. The comparison was based on parameters such as cost, energy consumption, process time, density, and hardness. The UHFIS process was performed using a 2.8 kW, 900 kHz system at 600 °C for six different durations (1 to 10 min). Conventional sintering, conversely, lasted 60 min at 600 °C. The results demonstrated that an increase in UHFIS duration led to a linear rise in energy consumption and cost. However, a 5-minute UHFIS duration was observed to optimize hardness and density values while keeping costs controlled. The UHFIS method provided a significant advantage by reducing the process time by a factor of 12 compared to conventional sintering. Conversely, due to its lower energy consumption, conventional furnace sintering offered a cost that was three times lower than UHFIS. In conclusion, the shorter process time and increased production capacity effectively compensate for the higher costs of UHFIS. With an optimized sintering duration, the UHFIS method exhibits significant potential for the efficient and economical production of highquality aluminum PM compacts in industrial and mass production settings.
Pediatric stainless-steel crowns (SSCs) have long been a preferred choice for treating carious posterior primary molars due to their durability and ease of application. This study aimed to assess and compare the fracture resistance of three different core restorative materials: resin-modified glass ionomer (RMGI), Tetric N-Ceram composite, and Empress composite when used in conjunction with SSCs. A total of 120 SSCs for primary molars were utilized, divided into three groups of 40 crowns each, with each group restored using one of the designated core materials. Following restoration, the samples were stored at 37°C for 48 hours and subsequently subjected to fracture resistance testing using a universal testing machine. The Empress Composite group demonstrated the highest fracture resistance, with a mean value of 92, followed by the Tetric N-Ceram Composite group at 32, and the RMGI group at 31. Statistical analysis revealed that the Empress Composite group’s fracture resistance was significantly greater than that of the other two groups (p< 0.05), while no significant difference was observed between the Tetric N-Ceram and RMGI groups. These findings highlight a clear relationship between the choice of core material and the fracture resistance of SSC restorations, with Empress Composite emerging as the most durable option among those tested.
In the present study, the behavior of a CoCrAlTaY coating deposited by HVOF was investigated in molten chloride salts (KCl–NaCl) at 700 °C for 200 h. Although a significant thickness loss was not observed in the tested coating, substantial diffusion of chloride ions was detected, leading to chromium depletion and the formation of an extensive interdiffusion zone. Therefore, it can be concluded that the CoCrAlTaY coating does not provide adequate protection, highlighting the need to explore alternative coatings or multilayer strategies to improve corrosion resistance in molten chloride environments.
In the final stage of zinc calcines processing, zinc is recovered by zinc electrowinning. However, the presence of germanium in the electrolyte seriously affects the current density in the electrowinning step. Since germanium is a critical and strategic material for the European Union according to the most recent foresight studies, this research has focused on an alternative route for the treatment of germanium concentrates (0.1 %wt Ge) obtained after the roasting step in conventional zinc processes. The results showed that this concentrate can be treated by leaching in mild acidic medium (90% germanium efficiency)-solvent extraction with an ionic liquid and alkaline stripping (99% germanium recovery), followed by neutralization and precipitation steps to yield GeO2 as end-product. The overall germanium recovery was around 85%.
Disc brake rotors are essential safety components in motorcycles, where their thermo-mechanical behavior under dynamic braking directly influences performance, durability, and reliability, particularly at high speeds. Conventional Gray cast-iron rotors, although widely used, often suffer from excessive thermal stress, significant deformation, and inadequate heat dissipation under severe braking conditions. Aluminium metal matrix composites (AMMCs) present advantages such as reduced weight and enhanced strength but encounter challenges including thermal expansion mismatch, localized stress concentration, and instability at elevated speeds. Despite their potential, few studies have explored microstructural tailoring of AMMCs to optimize their thermo-mechanical performance for practical braking applications. To address this, the present study systematically modifies AMMC constituents by incorporating tungsten carbide (WC) reinforcement while proportionally reducing aluminium content. A solid drilled disc rotor from a Bajaj Pulsar 150 cc was modeled in ANSYS Workbench and analyzed under transient coupled-field conditions across four braking speeds (800–2000 rpm). The work integrates transient Finite Element Analysis with experimental validation to compare Gray Cast Iron and three AMC formulations. Increasing WC reinforcement by 2% and reducing aluminium content improved thermal conductivity, hardness, and wear resistance while minimizing stress and deformation. Simulation and experimental results revealed that Gray Cast Iron experienced higher stress and temperature rise, whereas modified AMC2 demonstrated superior performance with lower peak temperatures, stable stress distribution, and minimal deformation. These findings highlight modified AMC2 as a promising material for next generation high-performance brake rotors, offering enhanced safety, durability, and weight efficiency.
