The combination of tungsten carbide (WC) and cobalt forms the most common cemented carbide on the market, as it is one of the most widely used materials industrially due to its excellent combination of properties. However, the search for a substitute binder is motivated by cobalt's high cost, toxicity, and low corrosion resistance. In this scenario, nickel (Ni) has stood out for meeting the necessary requirements and offering good corrosion resistance. However, its product presents a loss in mechanical properties. To improve these properties, the addition of alloying elements, such as aluminum (Al), was studied. This work aims to compare the micro-abrasive wear resistance of WC-Co and WC-Ni-Al cemented carbide. The micro-scale abrasion tests were carried out in a test rig with fixed-ball configuration, AISI 52100 steel ball and abrasive slurry composed of water and silicon carbide (SiC). The volume loss of the samples was the parameter used to determine micro-abrasive wear resistance. The samples were characterized before and after testing using scanning electron microscopy to identify the predominant wear mechanisms. WC-Ni-Al cemented carbide presented a microstructure similar to WC-Co, but pores and binder islands were observed. The micro-scale tests showed that WC-Ni-Al cemented carbide, despite its higher porosity, presented superior micro-abrasive wear resistance than WC-Co cemented carbide, indicating that the addition of Al contributed significantly to the increased wear resistance of this cemented carbide. This result also demonstrates the feasibility of using WC-Ni-Al cemented carbide as a substitute for WC-Co in applications involving abrasive wear.
Glass-ceramics based on the Na2O–Al2O3–SiO2 (NAS) system have attracted attention due to their potential in dental, refractory, and electronic applications, particularly associated with the nepheline (NaAlSiO4) phase. This study investigated the non-isothermal crystallization kinetics of a NAS glass containing CaO and TiO2 precursors (19.7 mol%) for the in situ formation of a glass-ceramic composed of nepheline and calcium titanate (CaTiO3). The kinetic parameters were determined using the Ligero method. The activation energy for crystallization (Ea) was equal to 195 ± 1 kJ/mol, remaining constant within the crystallized fraction range (x) of 0.40 to 0.50. The average Avrami index (n ≈ 2), associated with a saturated nucleation mechanism (m = 2), indicates a volumetric crystallization process. In addition, the time ratio (t0.75/t0.25 = 1.48) suggests crystal growth limited by diffusion, leading to the development of polyhedral morphologies. X-ray diffraction (XRD) analysis confirmed the formation of nepheline and CaTiO3 phases after heat treatment, while scanning electron microscopy (SEM) revealed a microstructure composed of polyhedral crystals, supporting the kinetic interpretation.
Titanium and titanium alloys are widely used to treat orthopedic and dental deficiencies and restorations because of their excellent biocompatibility and mechanical properties. However, they have some drawbacks, such as an inherent biological inertness that prevents them from adhering to cells or tissues, resulting in weak bone induction and angiogenesis abilities. Improving the biological properties of titanium and titanium alloy implants to increase osteogenesis and angiogenesis remains a significant challenge in the field of biomaterials. In addition, the continuous release of various metal ions in the microenvironment caused by body fluid corrosion can also lead to ultimate failure in implanting. Therefore, improving the corrosion resistance of both titanium and titanium alloys is an urgent task. In this study, we prepared cobalt titanium dioxide (Co-TiO2) coatings on medical titanium surfaces using micro arc oxidation. The surface characteristics, chemical composition, and structure of the coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the coatings was evaluated using an electrochemical workstation. These results confirmed that plasma electrolytic oxidation technology can be used to prepare cobalt titanium dioxide coatings in cobalt-containing electrolyte solutions successfully. The coating has a porous structure and a rough surface, and cobalt is successfully doped onto the coating surface. In addition, the cobalt titanium dioxide coating improved the corrosion resistance of titanium. In vitro experiments have shown that cobalt titanium dioxide coating can promote the adhesion and proliferation of MC3T3-E1 cells and has good biological activity. Conclusion: Cobalt titanium dioxide coatings can be prepared on medical titanium surfaces through plasma electrolytic oxidation. These coatings have good surface morphology and biological activity, improve the corrosion resistance of medical titanium, and have good clinical application prospects.
The discharge of synthetic dyes into industrial effluents represents a major environmental challenge due to their high stability and persistence in aquatic systems. Among available treatment strategies, membrane-based separation processes have emerged as promising alternatives for removing organic contaminants from water. However, improving membrane selectivity and efficiency toward different classes of dyes remains an important challenge. In this study, commercial PVDF membranes were modified with polydopamine (PDA) and a graphene oxide/polydopamine (GO/PDA) composite to evaluate their performance in removing methylene blue (MB, a cationic dye) and Congo red (CR, an anionic dye). The modified membranes were prepared through surface deposition of active layers and characterized using UV–Vis spectroscopy, FTIR spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle (WCA) measurements. Filtration experiments were carried out to assess dye removal efficiency and selectivity. The results showed that PDA-modified membranes achieved the highest retention efficiency for MB and the mixture, indicating a significant improvement over the unmodified PVDF membrane. However, the pristine membrane exhibited a higher retention of the anionic dye. The incorporation of GO contributed to a more homogeneous surface and enhanced selective filtration behavior. In mixed dye solutions (1:1 MB: CR), the GO/PDA membrane demonstrated a greater ability to preferentially remove CR, with a selectivity factor of 3.50. Overall, the deposition of PDA-based layers proved a promising strategy for enhancing nanofiltration membrane performance in the treatment of dye-containing effluents, while GO/PDA modification improved membrane selectivity.
Zircon is fundamental to geochronology, yet its crystal lattice accumulates radiation damage from α-decay of U and Th, progressively modifying physical properties. Raman spectroscopy provides a non-destructive probe of this damage through peak shifts and linewidth broadening, but mode-specific sensitivity and the role of thermal annealing remain poorly constrained. Here, we correlate effective uranium (eU), accumulated α-dose, and Raman linewidths in zircons from the Brazilian Carajás Province, Peixe Alkaline Suite, and the Fish Canyon Tuff standard using confocal micro-Raman spectroscopy and LA-ICP-MS. Linewidths increase non-linearly with dose and exhibit strong inter-mode correlations, with the external rotation (ER) mode providing the most robust proxy for structural disorder. Variability in linewidth–eU relationships indicates that Raman broadening primarily records time-integrated α-dose. Inter-band comparisons reveal mode-dependent annealing, while high-resolution mapping highlights micrometer-scale heterogeneity. These results demonstrate that robust quantification of radiation damage requires spatially resolved, multi-parameter calibration.
This study focuses on the synthesis and comprehensive characterization of Fe-doped TiO2 microspheres prepared via a modified internal gelation sol-gel method. This novel synthesis approach enhances environmental sustainability by avoiding toxic organic solvents and employing a single washing step with pressurized water. The synthesized microspheres exhibited a well-defined spherical morphology with diameters ranging from 200 to 400 μm. Structural integrity, notably the absence of cracks, was confirmed through scanning electron microscopy analysis. Fourier-transform infrared spectroscopy identified vibrational modes corresponding to -OH and Ti-OH bonds, which are crucial for surface interactions. X-ray diffraction and transmission electron microscopy confirmed the anatase phase as the predominant crystalline structure. Nitrogen gas adsorption-desorption analysis revealed a larger surface area and pore volume in samples with higher iron content (5wt% Fe). X-ray photoelectron spectroscopy analyses provided insights into the compositional dispersion across the samples and the role of Fe in the surface functionalization of TiO2.
Metal Additive Manufacturing (AM) via Wire Arc Additive Manufacturing (WAAM) has gained prominence as a viable alternative for the fabrication of complex metallic components. In this study, the feasibility of the dual-wire Gas Tungsten Arc Welding (GTAW) process was evaluated for the production of parts using ER310 and ER70S-6 consumables, employing an IMC DIGIPLUS A7 power source integrated with a Cartesian motion system. Characterization included tensile testing, microhardness measurements, and metallographic analysis. Microstructural analyses, combined with measurements performed on metallographic images, revealed a mean grain size of 3.04 µm, characteristic of the microstructural refinement promoted by the high cooling rates inherent to the WAAM process. Tensile results indicated that the material deposited with the ER310 + ER70S-6 combination exhibited a mean ultimate tensile strength ranging from 248 to 333 MPa and elongation values between 9 and 10%, which are lower than those observed for deposits produced solely with ER310 (320 – 430 MPa) and ER70S-6 (393 – 438 MPa), yet with comparable or superior ductility. The mean microhardness of the hybrid material was 233 ± 20 HV, significantly higher than that of ER310 (191 ± 8 HV) and ER70S-6 (161 ± 23.7 HV) single-wire deposits, evidencing the effect of consumable combination on the hardening behavior of the deposited material. Overall, the results demonstrate that the dual-wire GTAW process enables the production of a material exhibiting a balanced combination of mechanical strength, ductility, and hardness, alongside a stable microstructure and the absence of macroscopic defects, thereby confirming the potential of WAAM for engineering applications.
n-Type semiconducting CdSe thin films were synthesized by the chemical solution deposition technique from a CdCl2–N(CH2CH2OH)3–NH3–Na2SeSO3–Na2SO3 aqueous reaction system and the surface morphology was studied by atomic force microscopy as a function of reaction time. Two types of morphological structures were observed: (a) a base-layer consisting of coalesced primary particles, and (b) mountain-like structures maybe formed from the aggregation of secondary particles. The values of the base-layer particle size, mountain-like structure size, and roughness increased with the increase of reaction time. The sample deposited during the shorter reaction time was studied by X-ray photoelectron spectroscopy, which not only confirmed the presence of CdSe material, but also revealed the presence of sulfur on the film surface. A detailed survey X-ray photoelectron spectrum showing all the elements constituting the CdSe film surface is presented for the first time. Deconvolved photoelectron signals for Se 3d, C 1s, and Cd 3d are included. By fixing the main component of C 1s at 284.80 eV, the Cd 3d5/2 and Cd 3d3/2 peaks of CdSe were identified at binding energies of 405.31 and 412.06 eV, respectively, whereas the Se 3d5/2 and Se 3d3/2 were identified at 53.78 and 54.74 eV, respectively.
Mn-doped Fe3O4/reduced graphene oxide (rGO) nanocomposites derived from corncob biomass were successfully synthesized as sustainable magnetic nanomaterials for engineering applications. Biomass-derived rGO was prepared from corncob waste, while Mn-doped Fe3O4 nanoparticles were synthesized using a coprecipitation method and subsequently integrated with the rGO matrix. The structural, morphological, chemical, and magnetic properties of the synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), and vibrating sample magnetometry (VSM). XRD analysis confirmed the formation of a single-phase cubic spinel Fe3O4 structure with an average crystallite size of 11.5 nm and no detectable secondary phases. SEM observations revealed agglomerated ferrite particles uniformly distributed on layered rGO sheets, while EDS confirmed the presence of Fe, Mn, C, and O within the composite. The complementary results obtained from XRD, FTIR, SEM–EDS, and VSM collectively confirmed the successful formation of the Mn-doped Fe3O4/rGO nanocomposite. The synthesized material exhibited soft magnetic behavior with a saturation magnetization (Ms) of 32.83 emu g−1. The narrow hysteresis loop and magnetic response are consistent with the characteristics commonly observed in nanoscale ferrite nanocomposites, demonstrating its potential for electromagnetic interference shielding, magnetic separation, sensing technologies, and other sustainable magnetic engineering applications.
This work investigates the surface integrity of AISI 316L produced by additive manufacturing (AM) and subsequently machined, with an emphasis on residual stresses. A full factorial design was applied to evaluate the influence of laser power from AM and milling parameters, including cutting speed, cutting depth, feed rate, and cutting fluid. Eight samples were selected for Vickers microhardness characterization. Machined surfaces were examined by scanning electron microscopy. Microhardness results showed higher values at top surfaces, reaching increases of up to 22.7%. Variations in machining parameters significantly affected residual stresses, with changes of up to 500 MPa; all measured values were tensile. Surface roughness Rt ranged from 1.59 to 4.34 µm. The best surface integrity was achieved using 160 W laser power, 170 m/min cutting speed, 0.1 mm/tooth feed rate, 0.35 mm cutting depth, and cutting fluid. ANOVA identified feed rate as the most influential factor, followed by laser power and cutting depth. Machine learning models were developed for residual stress prediction, with PCA-RBFN showing superior performance for parallel residual stress (R2 = 94,53%) and SVM for perpendicular residual stress (R2 = 89.85%). The hybrid approach enabled isolation of individual parameter effects while minimizing interactions between AM and machining.
Tungsten oxide thin films were deposited by reactive high-power impulse sputtering using a facing-target configuration (HiP-FTS), and the influence of discharge energy on film morphology and hydrogen response was investigated. The pulse width was varied at a constant repetition frequency to control the discharge energy delivered per pulse under identical gas flow conditions. An increase in pulse width enhanced the deposition rate and promoted smooth and compact surface morphologies, as indicated by SEM and AFM observations. Under fixed oxygen flow conditions, changes in film appearance and optical behavior suggested possible changes related to oxygen-deficient-like optical behavior at longer pulse widths. The hydrogen-induced optical response of Pt-loaded films was evaluated under 4% H2 in Ar at room temperature. The films exhibited limited gasochromic response despite identical Pt loading conditions, indicating that hydrogen incorporation within the film structure may be limited by the compact microstructure formed under HiP-FTS conditions. These results indicate that discharge energy strongly influences film morphology, optical behavior, and hydrogen response in tungsten oxide thin films deposited by reactive high-power impulse sputtering with a facing-target configuration.
The influence of solution and aging heat-treatments on the corrosion behavior of a biodegradable Mg–Y–Gd–Zr alloy was investigated. Electrochemical behavior was assessed by potentiodynamic polarization curves and electrochemical impedance spectroscopy in an aerated 0.9 wt.% NaCl solution at 37 °C ± 0.1, complemented by SEM, EDS, and XRD analyses of corrosion-products. The as-cast condition exhibited the highest polarization resistance and impedance modulus, attributed to a thicker and more resistive corrosion-product layer, despite microstructural heterogeneity. Solution heat-treatment (525 °C/24 h) homogenized the microstructure and shifted the corrosion potential to nobler values, but produced a thinner, less protective film and reduced corrosion resistance. Among aged conditions, aging at 250 °C for 100 h yielded the best performance, with higher polarization resistance and impedance modulus values indicative of a more uniform and stable surface layer. Overall, the results demonstrate that corrosion behavior is primarily governed by the stability and resistive character of the corrosion-product layer, which is strongly controlled by the heat-treatment-induced microstructural state.
The operational conditions for oil and gas production frequently change. Consequently, equipment and pipes originally specified for milder conditions may no longer meet the standards requirements. This study addresses the safety of maintaining AISI304 and 316L flexible pipe carcasses in sour service with high chloride content. A rigorous laboratory testing program was carried out with specimens machined from field-removed carcass sections, designed to reproduce a more aggressive scenario than current operational conditions. The methodology employed the U-bend technique to apply stress in the plastic regime, combined with crevice formers, and included welded samples to study the effect of sensitization. The results confirmed that sensitization and cold work influences corrosion susceptibility of both steels. Similar performance was observed to AISI304 and AISI316L in high chloride and H2S environments. This good field performance is attributed to the influence of H2S, in concentrations above 100ppm. The formation of a dense sulfide layer is favored, constraining pit development. A new unified operational limit was established for AISI304 and AISI316L carcass: high chloride environment, 60oC and 1≤[H2S]≤5% in gas mixture. The experimental data provides essential criteria for life extension and reuse of flexible assets under conditions not specified on current standards.
The quantitative analysis of recrystallization microstructures requires methodologies capable of describing interfacial evolution clearly and with minimal reliance on phenomenological assumptions. Although microstructural paths relating interfacial surface area density to transformed volume fraction are well-established in experimental and hybrid modeling studies, their determination commonly depends on analytical kinetic formulations or fitted parameters. In this work, a fully discrete formulation of the recrystallization microstructural path is proposed based on three-dimensional hybrid cellular automata simulations. All relevant descriptors, including the transformed volume fraction and the interfacial surface area density between recrystallized and non-recrystallized regions, are obtained directly from voxel-level geometric information, without invoking phenomenological kinetic equations or auxiliary correction factors. The methodology is applied to different growth geometries, encompassing classical face-based cellular automata growth as well as spherical and spheroidal grain growth within a hybrid framework. The resulting microstructural paths reproduce the characteristic non-monotonic behavior reported in experimental and computational studies in the literature. Comparative analyses show that grain morphology significantly influences microstructural path evolution, highlighting the importance of geometric assumptions in recrystallization modeling. The proposed approach provides a transparent and reproducible framework for analyzing recrystallization microstructures and offers an independent, geometry-based perspective that complements traditional kinetic descriptions.
This work analyzed the Ti-10Mo-3Nb, a biomedical alloy very promising and deserving of further study in order to contribute to the literature. Microstructural characterization, evaluation of mechanical properties and analysis of electrochemical behavior are part of the methodology. The electrochemical assays were evaluated by: Open Circuit Potential (OCP), Polarization Curves and Chronoamperometry tests. All tests were performed in the following media: M1 = 0.9 wt% NaCl, M2 = 0.9 wt% NaCl pH 1.0, M3 = 0.35 wt% NaCl. The alloy was producted in laboratory and solution-treated at 950ºC under argon atmosphere for 1 hour and then quenched in water. Results showed that the microstructure presented β matrix with distribution of α`` and ω phases, analised by X-ray diffraction and Scanning Electron Microscopy (SEM). The value measured of Elastic Modulus was 105.51 GPa and hardeness 332.08 HV. The OCP response and the polarization curves obtained in media M1 and M2 showed that the Ti-10Mo-3Nb alloy exhibited greater corrosion resistance compared to the Ti-6Al-4V alloy. The evaluation of the Ti-10Mo-3Nb alloy behavior in relation to the composition of corrosive medium showed that the alloy is more susceptible to corrosion in media with higher chloride ion concentration and high acidity (M2).
Additive manufacturing (AM) is a powerful platform for developing functional materials with broad applications across healthcare, consumer goods and industrial sectors. This study presents a pioneering polypropylene (PP) filament enhanced with a ZnO-based glassy ceramic additive (Si–Na–Al matrix), specifically designed for 3D printing. Beyond introducing antiviral functionality, the formulation overcomes a long-standing limitation in AM of polyolefins, significantly improving printability by reducing thermal shrinkage and enhancing interlayer adhesion. PP composites were fabricated with 2%, 6%, and 10% additive loadings and evaluated for morphological (SEM-BSE), chemical (FTIR, EDS) and biological performance. Antiviral assays, conducted according to ISO 21702 using exposure times of 15 and 120 minutes, demonstrated viral load reductions of up to 99.68% against betacoronavirus (MHV-3) and 96.84% against adenovirus at the highest additive concentration. In contrast, antibacterial tests based on ISO 22196 against E. coli and S. aureus showed no significant activity, likely due to limited additive release from the polymer matrix. These results establish a novel antiviral 3D-printable PP composite with improved manufacturing performance, offering a versatile solution for applications demanding structural integrity combined with bioactive antiviral surfaces.
In the manufacture of graphene-reinforced aluminum composites, powder metallurgy has been the primary production method, proving to be highly effective. The present work addresses the production and characterization of aluminum matrix composites reinforced with graphene-based nanomaterials. The production route employed the powder metallurgy technique and was processed in two stages: first by mixing in different liquid media, and second by using distinct mixing methods. The sintered samples from the first stage were evaluated for their density, and the sintered samples from the second stage were subjected to mechanical microhardness tests. The results of the first stage indicated that among the solvents used for mixing, acetone and ethanol stood out, providing compacts with densification above 92%. In the second stage, Al/rGr composite samples produced by the mechanical mixing method using a helical impeller showed the greatest increase in hardness, achieving a 60.5% increase compared to pure aluminum.
In this experimental study, we present and discuss the effects of 3, 5, and 7 wt.% Si additions on the thermal parameters, phase transformations, microstructural patterns, microhardness, and 3D porous formation in binary Al - 2 wt.% Cu alloy. Through the phase diagram and Thermo-Calc Scheil simulation, one can determine the growth sequence of the phases during the cooling process. With slow cooling curves and its second derivatives, liquidus temperatures can be found. An approach based on the second derivative curve was adopted to determine the onset of solidification and subsequent phase transformations. The experimental results determined with the slow cooling curves are corroborated by those calculated by Thermo-Calc software. A data acquisition system was used to record the experimental slow cooling curves for subsequent thermal analysis. Higher silicon concentrations, shorter solidification range and refined microstructures were key factors acting during solidification, which served to conditions changes in the microhardness and 3D porous formation. The relationships between porosity content with silicon concentration (PC = 1.46%Si0.7813 with R2 = 0.97) and secondary dendritic arm spacing (PC = 1692.7λ2-1.44 with R2 = 0.99) are presented and discussed from experimental equations. This result indicates that porous formation during solidification process is closely connected to the silicon concentrations and dendrite arm spacings.
In this study nylon 66 (N66), glass fiber–reinforced nylon 66 (GFN66), and talc particulate–filled glass fiber–reinforced nylon 66 (T-GFN66) hybrid composites were fabricated using compounding process and injection moulding technique. Test was performed by varying the input factors (impact velocity, impingement angle, and constitute of composite). Study intended to explore the combined effect of input factors on erosion wear rate (EWR) of the composites. Data-driven machine learning (ML) approach was applied to analyse and predict the EWR of the N66 and its hybrid composites. Experimental results showed that EWR increased with increase in impact velocity and decreased with an addition of glass fiber and talc filler contents. T-GFN66 composite exhibited superior erosion wear resistance than N66 and GFN66. Furthermore, experimental data were fed into the four ML models and compared using their performance metrics. It was observed that among all the developed ML models, gradient boosting machine (GBM) model found to be superior in predicting the erosion wear performance of N66 composite with R2 value of 0.9666. Eroded surface topography was analysed using 3D optical profilometer to establish the relationship between surface parameters and EWR. Worn morphology was conducted using field emission scanning electron microscopy (FESEM) to observe wear mechanisms endured by the N66 composites.
