Abstract in English:

Contemporary agriculture faces the challenge of reconciling productivity and sustainability, making hydroponics a promising alternative. However, the lack of biodegradable materials that combine mechanical performance, stability, and compatibility with nutrient solutions limits its expansion. In this context, this study proposes innovative composites based on poly (butylene adipate-co-terephthalate) (PBAT), functionalized with activated carbon (AC) and the cationic surfactant CTAB, targeting applications in hydroponic systems. The formulations (PBAT, PBAT/5AC, PBAT/5AC/1CTAB, and PBAT/5AC/2CTAB) were processed by extrusion and injection and characterized by mechanical testing (ASTM D638), thermogravimetric analysis (TGA/DTG), scanning electron microscopy (SEM), and contact angle (ASTM D7334-08). CTAB acted as a functionalizing agent, improving CA dispersion and reducing agglomerates, which resulted in gains of 15.53% in the modulus of elasticity and 4.05% in tensile strength, in addition to greater surface hydrophilicity. Despite lower thermal stability, the properties obtained favor the adhesion of aqueous solutions, making the composites promising for sustainable substrates and components in hydroponic cultivation.

Abstract in English:

3D printing has expanded into diverse fields, including water treatment, sensors, scaffolds, and agriculture. This study evaluates the incorporation of magnesium oxide into activated carbon within a commercial PLA/PBAT blend for the production of filaments via Fused Filament Fabrication (FFF). The addition of magnesium oxide increased the elastic modulus by more than 50% without altering tensile strength. Density reached up to 1.3 g/cm3, with no significant impact on the application. The combined effect of magnesium oxide and activated carbon enhanced soil degradability to approximately 8% within 60 days, compared with formulations containing only activated carbon. Thermal variations, such as an increase in crystallization temperature from 67.5 °C to 76 °C, did not compromise processability. Despite the dimensional instability of the filaments, it was possible to print functional parts with good quality. These results demonstrate a sustainable and innovative route for developing advanced filaments tailored for additive manufacturing within the context of Industry 4.0.

Abstract in English:

3D printing technology enables the fabrication of complex-structured ceramic components, while Digital Light Processing (DLP) offers superior precision and faster printing speeds. This study prepared zirconia slurries with 45 vol% solid loading using particle gradation technology with different coarse-to-fine powder ratios, systematically investigating the effects of particle size distribution on slurry rheological properties, curing characteristics, and sintered body performance. Experimental results demonstrated that the 80:20 ratio exhibited optimal comprehensive performance. At this ratio, the zirconia slurry showed a viscosity of 4.94 Pa·s at 50 s−1 shear rate and achieved a curing depth of 165 μm at 120 mJ/cm2 energy density. This originates from increased interparticle surface contact due to fine particle incorporation, which enhances steric hindrance effects and consequently reduces powder-resin matrix fluidity, while the enlarged specific surface area significantly improves ultraviolet (UV) light absorption efficiency. After sintering at 1550°C, preferential diffusion of fine particles into grain boundary gaps promoted sintering densification, concurrently inhibiting abnormal grain growth and reducing light-scattering defects, thereby achieving simultaneous improvement in both mechanical properties and optical translucency.

Abstract in English:

One of the solutions to flooding problems, especially in large cities, is the use of permeable pavements that can be produced using mineral waste, reducing costs and environmental impacts, and generating a circular economy. In this study, wastes from the exploitation and processing of kaolin, scheelite, and granite were used to produce ceramic permeable pavements. After characterization, the mineral wastes were mixed with a commercial red clay with samples uniaxially pressed (20 MPa) and sintered at 1050, 1100 and 1150 °C, with a heating rate of 5 °C/min. The formulations of kaolin processing residues sintered at 1050 °C and scheelite processing residues sintered at 1100 °C stand out with the highest porosity (close to 40%), high permeability (up to 7.42×10−4 m/s) and flexural strength ranging from 2.45 to 4MPa. These results emphasize the role of formulation parameters, highlighting the potential of ceramic permeable pavements as a high-performance, cost-effective, and sustainable solution.

Abstract in English:

WC-Co cemented carbide exhibits remarkable mechanical properties, with applications in several engineering areas. However, its high cost, toxicity, and the search for cemented carbides with greater corrosion resistance have led to a demand for an alternative binder phase. In this study, the corrosion behavior of WC–NiAl cemented carbide (90 wt.% WC, 9.5 wt.% Ni, and 0.5 wt.% Al), processed by conventional powder metallurgy, was compared with that of conventional WC–Co cemented carbide in a 3.5 wt.% NaCl solution. The samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction before and after corrosion tests. In the electrochemical tests—open circuit potential, linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)—the sample with nickel and aluminum binder exhibited more noble potentials, lower current density values, and higher total impedance than the sample with the cobalt binder.

Abstract in English:

With the growth of the 3D printing industry, there are concerns regarding the PLA residues from the manufacturer and the temporary use of the material. To address these concerns, this work presented a sustainable approach to recycling polylactic acid (PLA) residues from 3D printing by incorporating graphene as a reinforcement material. Aiming to simulate a mixed material scenario, the residue is generated by processing on a Creality Ender 3 printer, heated to 200 °C at a speed of 25 mm/s. Then, PLA residues were ground and mixed using a co-rotating twin-screw extruder at 190 ºC with 0.18% by weight of graphene. In general, graphene was incorporated, resulting in a homogeneous distribution that does not contribute to increasing the tensile strength compared to recycled PLA; however, it is higher than that of the original PLA filament. Regarding the thermal properties, the reprocessed material retains its original thermal stability, with a slight decrease in the degradation temperature. The recycled PLA exhibited a crystallinity of 20.3%, which was higher than that of the original PLA filaments and recycled PLA with graphene (3.4%). In conclusion, PLA residues from 3D printing can be recycled to obtain PLA nanocomposites without compromising the mechanical and thermal properties.

Abstract in English:

This study evaluates electropolishing as a surface preparation method for the Ti-6Al-4V ELI alloy for implant applications, aiming to reduce surface roughness and improve wettability behavior. Alloy samples were subjected to electropolishing in a solution of acetic acid, perchloric acid, and glycerol, under different voltages (13–18 V) and times (5, 10, and 15 min). The surfaces were characterized by scanning electron microscopy, profilometry, and contact angle measurements. Higher voltages and longer anodizing times favored roughness reduction. The average Ra, calculated from samples analyzed in triplicate, was 70.207 nm, with a standard deviation of 19.260 nm, obtained under the condition of 18 V for 15 minutes. The largest contact angles, 112.62° and 110.74°, were observed at 14 V for 10 and 15 minutes, respectively, suggesting that factors beyond surface topography influence wettability. It was concluded that electropolishing is an effective method for preparing the surface of Ti-6Al-4V ELI, with potential for implant applications, and that the parameters should be adjusted according to the desired performance (surface finish, hydrophobicity, or hydrophilicity).

Abstract in English:

This study explores the combined influence of temperature and magnetic field on the corrosion behavior of AA6060 aluminum wire in seawater. By employing electrochemical techniques, including free corrosion tests conducted with and without a low-intensity magnetic field, the research aims to assess the impact of these factors on corrosion rates and mechanisms. Additionally, surface analysis techniques are utilized to characterize the corrosion products and examine the morphology of the corroded surfaces. The findings are expected to reveal that both temperature and magnetic field significantly affect the corrosion behavior of AA6060. While elevated temperatures generally accelerate corrosion by enhancing the kinetics of electrochemical reactions, the effect of the magnetic field varies depending on its orientation and strength, potentially either accelerating or mitigating the corrosion process.

Abstract in English:

Biodegradable polymeric films with natural active compounds offer a sustainable approach to improving food safety and self-life. This study developed bioactive films using arrowroot starch (AS) and pectin extract (PE) from yellow passion fruit peel via solution casting. Sucrose (SU) and rosemary essential oil (REO) were incorporated to enhance functional properties. Films were characterized by optical, mechanical, barrier, antioxidant, and antimicrobial proprieties. PE acted as a plasticizer and increased antioxidant potential due to its high phenolic content, confirmed by DPPH and FRAP assays. REO exhibited moderate antimicrobial activity against Staphylococcus aureus and Escherichia coli, mainly attributed to α-pinene. Although water vapor permeability of formulation F2 (0.5% REO, 1.4% SU) doubled compared to control, transparency, color, and tensile strength remained stable. F2 also showed a 5.23% increase in DPPH inhibition. These findings highlight the potential of films developed as active, sustainable packaging materials.

Abstract in English:

Aurivillius type ferroelectric ceramics, SrBi2-xLaxNb2O9 were synthesized through the molten salt method to clarify how La3+ substitution influences both the crystal framework and the ferroelectric response. XRD data revealed the formation of a single orthorhombic A21am phase for all compositions which was further verified through Le Bail refinement. FTIR further supported the stability of Nb-O linkages. Microstructural examination by SEM indicated that increasing La3+ content suppressed grain growth. Dielectric measurements showed a systematic lowering of the ferroelectric transition temperature, consistent with enhanced orthorhombicity and the reduced stereoactivity of the Bi3+ 6s2 lone pair. Polarization hysteresis loops demonstrated that La3+ modification improved room temperature polarization behavior, attributed to reduced dielectric loss and more mobile domain walls. These results establish a clear link between structural distortion and ferroelectric response in La3+ modified SrBi2Nb2O9, underscoring the potential of this system as a model compound for understanding structure property relationships in layered ferroelectrics.

Abstract in English:

This work evaluates the adhesion strength of FeCoCrNi, FeCr, and FeCoCr coatings produced by electric-arc thermal spraying on carbon steel, using the interfacial indentation test. Microstructural analysis revealed low porosity and oxide content. The test yielded toughness (K) values of 1.05, 1.10, and 1.17 MPa·m1/2 for FeCoCrNi, FeCr, and FeCoCr, respectively, with FeCoCr showing the highest resistance to crack propagation. Interface microhardness ranged from 808 to 978 HV, and Young’s modulus from 129 to 183 GPa. Residual compressive stresses up to -240 MPa at the interface favored adhesion, consistent with hardness data. Finite element modeling using ANSYS Workbench 2021R closely matched experimental results, with deviations between 1% and 11%. Compared to the ASTM C633 tensile test, the interfacial indentation method provided equal or superior reliability, simpler execution, and lower cost. Results confirm the influence of alloy composition and microstructure on adhesion and validate interfacial indentation as a robust tool.

Abstract in English:

Al and Zn-based metallic coatings are widely used to protect a significant diversity of steel components and structures from corrosion. The quality of coatings depends largely on their properties and spraying conditions. The purpose of this work was to find the optimal thermal spray parameters to manufacture Al-4.2%Zn-2%Mg alloy coatings on an A 36 steel substrate from diagnostic tests of porosity, adherence, and microstructure. Furthermore, adhesion of the coating onto the substrate after the precipitation heat treatment was investigated. Microstructural characterization was performed by scanning electron microscopy (SEM), the porosity was determined by Archimedes principle and the adhesion was evaluated by tensile testing. The optimum thermal spray distance, maintaining the thickness of the coating constant at 300 μm, was 0.20 m, in which the lowest porosity percent (9%) and the highest adherence (7.16 MPa) were attained. The coating increase of thickness and the post-heat treatment precipitation caused an adhesion decrease. However, heat-treated coatings with thicknesses between 150 and 300 µm could be used for cathodic protection of A36 steel because their adherence values (7.33 and 6.69 MPa, respectively) meet those required by the flame thermal spraying process.

Abstract in English:

The transition from upper-to-lower bainite in carbon steels is a complex process yet not fully explored. This study examines such transition in a 0.7C, 0.74Mn, 0.61Si, 0.2Cr (wt%) low-alloy steel using a comprehensive approach that integrates dilatometry, scanning electron microscopy (SEM), ex-situ HEXRD, and microhardness testing. Microhardness and dislocation density were found strongly coupled, both increasing with decreasing austempering temperature and presenting changing trends at approximately 350°C and 300°C. Likewise, an Arrhenius plot derived from the curves of transformed fraction as a function of austempering temperature presented the same behaviour. These turning points are considered, respectively, the onset and the end of the transitional interval between upper and lower bainite. Furthermore, SEM analyses confirmed a progressive change in morphology, from coarse upper bainite at high temperatures (400°C), to a mixture of upper and lower bainite in the transitional range, and finally to exclusively fine lower bainite at low temperatures (275°C). The results support that the upper-to-lower bainite transition is not a discrete step but a continuum and offer insights into the interplay between bainite morphology, overall transformation kinetics, and microhardness, which are critical for optimizing heat treatments routes.

Abstract in English:

Folic acid is associated with the growth and development of the nervous system, playing a crucial role in the therapy and differentiation of neural stem cells and the hematopoietic system. In this study, we prepared scaffolds from the biopolymers chitosan and collagen and added the micronutrient folic acid (FA), also known as vitamin B9. We synthesized a scaffold with FA in β-cyclodextrin to prolong the time required for its release. This increased the interaction between the polymeric matrix and Neuro 2A cells. Morphological, chemical and thermal characteristics, cell solutions and adhesion were verified. Cytocompatibility testing on Neuro 2A cells showed that none of the FA-containing scaffolds was harmful to the cells. In fact, FA combined with β-cyclodextrin made the cells more viable and helped them adhere to each other, which made them grow faster. For this reason, scaffolds have potential for use in neuronal tissue engineering as provisional supports for the growth, specialization, and differentiation of neuronal cells.

Abstract in English:

Transparent conductive oxide (TCO) thin films are crucial for modern electronic devices. Among them, amorphous indium-zinc-tin oxide (IZTO) films have attracted considerable interest due to their potential for flexible applications. This work systematically investigates the influence of oxygen partial pressure and oxidative annealing on the properties of IZTO films. IZTO films deposited at 3% oxygen partial pressure exhibited a low sheet resistance of 19.5 Ω/□, high visible (TVIS = 83.6%) and near-infrared (TNIR = 90.0%) transmittance. After oxidative annealing, IZTO films showed an increased sheet resistance of 29.2 Ω/□, and a high Hall mobility of 51.4 cm2·V−1·s−1, while retaining excellent optical transparency. All the films showed amorphous phase and smooth surface structure. These results are valuable for developing high-performance, transparent amorphous electrodes in flexible optoelectronic applications.

Abstract in English:

Poly(lactic acid) (PLA)-based films containing 0.5 and 1.5 wt% of TiO2 or ZnO nanoparticles were prepared by solvent casting and evaluated in terms of thermal, mechanical, optical, structural, and ecotoxicological performance, targeting food packaging applications. X-ray diffraction and scanning electron microscopy revealed that low nanoparticle contents promoted partial crystalline ordering and relatively homogeneous dispersion, whereas higher loadings led to agglomeration and reduced crystallinity. Thermogravimetric analysis showed that the incorporation of 0.5 wt% TiO2 increased the onset decomposition temperature of PLA from 303.3 to 322.8 °C. In contrast, higher nanoparticle contents and all ZnO-containing films exhibited reduced thermal stability and lower glass transition temperatures, with Tg decreasing from 51.3 °C (PLA) to 44.0 °C for PLA15ZnO. Nanoindentation demonstrated a significant increase in nanohardness for all nanocomposites, reaching improvements of up to ~27% compared to neat PLA. Optical analysis showed effective UV-shielding below 400 nm and preservation of visible-light transmittance above ~85% for films containing 0.5 wt% ZnO, whereas higher TiO2 contents induced pronounced opacity and color changes. Germination assays using lettuce and cucumber indicated concentration-dependent phytotoxic effects for TiO2, while ZnO showed neutral or slightly positive effects at low concentrations.

Abstract in English:

Aqueous dispersions of colloidal silica (CS) are commonly employed in high-alumina refractory castables to prepare in situ mullite, behaving simultaneously as a liquid medium, binder, and SiO2-source. Despite such technological interest, CS was not explored as a uniaxial pressing additive to replace organic binders and promote earlier strengthening during sintering. This study mixed alumina particles with varying amounts of CS to compare structures composed of the same raw materials, shaped by different processing techniques. Such compositions were pressed as bars or cast into cylinders, and their microstructure and physical properties evolution were assessed during sintering (700-1500ºC). Cast samples developed a homogeneous microstructure comprised of alumina particles surrounded by a gelled CS phase; in contrast, the pressed samples generated SiO2-rich spherical clusters, originating from the original CS droplets, surrounded by alumina. Such a heterogeneous microstructure persisted during sintering, when the silica nanoparticles crystallized before forming mullite. Directly cast samples developed a granular microstructure of alumina-mullite, with traces of cristobalite. In pressed samples, regions with higher SiO2 concentration developed acicular mullite crystals, imbibed in a matrix of alumina and cristobalite. Increasing the CS content in both cases enhanced porosity and decreased strength after sintering at temperatures above 1100 °C.

Abstract in English:

Selecting materials for metallic structures such as transmission towers requires careful consideration of environmental dynamics, climate change, atmospheric variations, and human activity, all of which directly affect corrosion behavior. Relying on generic or incomplete data can lead to premature material degradation and increased maintenance costs. This study focuses on a 1,150 km transmission line spanning the Brazilian states of Ceará, Piauí, and Maranhão, where material selection was initially based on theoretical estimates of atmospheric aggressiveness (C3 category). However, frequent maintenance and component replacements indicated underestimated corrosivity. To improve understanding, environmental parameters (humidity, salinity, precipitation, and wind) were monitored, and field corrosion rates were determined using AISI 1020 and galvanized steel samples. Complementary analyses included electrochemical testing, microstructural evaluation, and accelerated aging under industrial and saline conditions. Additionally, an artificial intelligence tool based on feedforward neural networks was developed to enable rapid corrosivity classification through RGB/HSV image analysis, without requiring long-term field exposure or specialized equipment. After one year, the environment was reclassified as C5–Cx (extreme aggressiveness). These results highlight the importance of location-specific assessments over general assumptions and demonstrate how AI-based tools can enhance decision-making and maintenance strategies for more resilient power transmission infrastructure in a changing climate.

Abstract in English:

In the present investigation, aluminium Metal Matrix Composites (MMCs) were synthesized by reinforcing nano TiO2 particles at varying weight percentages (0.5 ,1.5,2.5 and 3.5 wt%) into an AA6061 molten aluminium matrix using the stir casting method. The synthesized composites were characterized using optical microscopic analysis, Scanning Electron Microscopy (SEM) and X- ray diffraction (XRD). The hardness and tensile properties of the composites were evaluated. The analysis of mechanical properties revealed that the T6 composite containing 0.5 wt% nano TiO2 particles had a maximum hardness of 79.6 BHN compared to other T6 samples and as well as ac-cast samples. Ultimate tensile strength and yield strength of T6 composite containing 0.5 wt% TiO2 was found to be (180 MPa and 135 MPa) higher than other T6 composites and as cast samples. Fractography of Al MMC containing 0.5 wt% nano TiO2 particles revealed ductile -brittle fracture mode in the T6 condition.

Abstract in English:

Optimizing laser welding of dissimilar materials is critical for aerospace applications, where high-performance joints are required under stringent weight and reliability constraints. This study presents a multiphysics modeling framework for predicting heat flux and residual stress development in laser-welded AA6013/Ti-6Al-4V dissimilar joints. A finite element model was implemented in COMSOL Multiphysics to simulate transient heat transfer, thermal gradients, and thermo-mechanical stress evolution, and was validated against experimentally measured thermal cycles, yielding deviations of 2.5–6%. The results demonstrate that heat input (HI) and beam offset strongly govern the temperature field, residual-stress distribution, and intermetallic-compound (IMC) formation at the Al/Ti interface. For condition T7 (HI = 9.6 J/mm; offset = 0.3 mm), the model predicted a peak temperature of 5950 K in the high-energy interaction region. A comparison between conditions T6 and T9 showed that, under identical beam intensity, reducing the welding speed increased the energy absorbed by the titanium side, with a 22% reduction in heat dissipated by conduction relative to T6. Residual stresses decreased with distance from the laser path; for a fixed offset, increasing HI increased compressive residual stress, reaching a maximum of 26 MPa (≈10% of the AA6013 yield strength) at HI = 24 J/mm and remaining nearly constant thereafter. In addition, higher cooling rates reduced IMC thickness from approximately 7 µm to 3 µm, indicating improved metallurgical conditions. Overall, the validated model provides a predictive tool for selecting process parameters to minimize residual stresses and control IMC growth, supporting the development of aerospace-grade AA6013/Ti-6Al-4V dissimilar laser welds.

Abstract in English:

Copper with higher electrical conductivity, reinforced with high-performance ceramic particulates, is suitable for use in industrial electrical contacts, connectors, and thermal management systems due to its tailorable mechanical properties, which improve its wear resistance accordingly. The stronger effect of particle mixing and sintering temperature variation is tailoring the mechanical properties, allowing the copper matrix to be met for the desired applications. The influence of sintering temperature and alumina particulate ratio on the microstructure, compressive strength, ultimate tensile strength, flexural strength, and micro hardness of copper–alumina composites were systematically studied. Copper matrices were reinforced with 5, 10, 15, and 20 vol.% alumina powder and sintered at three different temperatures: 750 °C, 800 °C, and 850 °C. The composite containing 15 vol.% alumina sintered at 750 °C exhibited the highest compressive strength. The maximum ultimate tensile strength was observed in the composite with 20 vol. % alumina sintered at 850 °C. The greatest flexural strength was achieved with 5 vol.% alumina at 850 °C, while the highest micro hardness was recorded in the composite containing 15 vol.% alumina sintered at 800 °C.

Abstract in English:

This study investigates the complementary modulation of chitosan/keratin hydrogels through the combined use of hexamethylene diisocyanate (HDI) and Pluronic F-68, aiming to tailor mechanical stability, porosity, and biological performance for wound healing applications. Covalent crosslinking by HDI enhanced network integrity and mechanical resistance, while Pluronic F-68 promoted micelle-templated porosity, increased hydration, and improved permeability. The hydrogels exhibited compressive strength values ranging from 33.5 to 65.9 MPa, swelling capacities of up to approximately 160%, and porosity values approaching 60%, depending on composition. Increasing HDI content reduced solubility to approximately 15%, indicating improved structural stability. All formulations were cytocompatible, maintaining cell viability above 70%, with Pluronic-containing systems reaching values close to 100%. These results demonstrate that the independent control of crosslinking density and porosity enables the identification of compositional balance zones that reconcile mechanical integrity and biological response, supporting the rational design of adaptable hydrogel platforms for wound healing.

Abstract in English:

Three different regions in the heat-affected zone are formed when the shielding gas mixture during the GMAW procedure is argon-rich. The microstructural characterization and corrosion susceptibility of different heat-affected zone (HAZ) regions in welds of UNS S31803(2205) duplex stainless steel (DSS), were evaluated by optical images, scanning electron microscopy and transmission electron microscopy. The pitting susceptibility of the different regions in the HAZ was evaluated by pitting corrosion tests in an acidified ferric chloride solution. The analyzed HAZ regions showed different HAZ dimensions and microstructural aspects as grain size, phase fractions, morphologies and compositions that influenced the pitting resistance. The HAZ region induced by the lower cooling rate showed larger ferrite grain size. In this region, the Widmanstätten and intragranular austenite fractions were higher, indicating greater susceptibility to pitting corrosion. The weld with the highest heat input showed the lowest resistance to pitting corrosion.

Abstract in English:

Super duplex stainless steels (SDSS) have a microstructure composed of approximately equal fractions of ferrite and austenite. However, depending on the chemical composition and thermomechanical conditions, precipitation of deleterious intermetallic phases may occur, compromising their properties. This work investigated the influence of isothermal aging time and temperature on the phase transformation of a super duplex steel subjected to heat treatments at 700°C, 800°C and 900°C, for 1 and 2 hours, with water cooling. Initially, all samples were solubilized at 1100°C for 30 minutes for microstructural homogenization. The innovative scanning magnetic microscopy (SMM) technique was used to access variations in remaining magnetization, whose application in steel phase detection has received relatively limited attention in the literature. However, the image processing in SDSS proposed in this work had not yet been reported in the literature, giving the study a pioneering character. Since variations in magnetic properties can result from microstructural changes, this technique, although still requiring further experimentation, presents interesting results. For validation, the results were compared with established methods, such as ferritoscope, vibrating sample magnetometry (VSM), X-ray Diffraction (XRD) and optical microscopy (OM). The results demonstrate that increasing the aging time and temperature promotes a significant reduction in the ferrite fraction (ferromagnetic), accompanied by the dispersed formation of the σ phase and partial transformation into austenite (paramagnetic). Differences between the characterization methods, especially at advanced stages of aging, suggest the possible presence of intermetallic deleterious phases or finely dispersed carbides. As a main result, magnetic techniques are promising for the thorough processing of SDSS.

Abstract in English:

This study compiles experimental knowledge on the surface preparation and painting of SAE 4150 steel parts using a waterborne coating based on a thermosetting polyester–amino resin as a replacement for a conventional solvent-based coating system. Tests, analyses, and process adjustments were conducted in a production environment, aiming to optimize adhesion and coating resistance. The variables evaluated included the type of mechanical cleaning process (grinding or brushing), the type and concentration of chemical cleaning agents (degreasers), the application of a zirconium-based nanoconversion coating, the dry film thickness of the coating, and the paint curing temperature. This study elucidates the combined effects of surface roughness, film thickness, curing conditions, and alkaline exposure on the chemical degradation mechanisms of polyester–amino waterborne coatings applied to steel substrates. Optimal process parameters were achieved using a brushing process with a medium brush grit size of 100, chemical cleaning with an alkaline degreaser at a 1% concentration, and painting with a dry film thickness of 30 µm followed by curing at 175ºC. The use of a nanoconversion coating was not justified, since the substrate roughness obtained after brushing was sufficient to ensure adequate paint adhesion. The results demonstrated that the waterborne paint outperformed the solvent-based paint originally used in the production line, while also providing a more sustainable solution in terms of environmental impact and occupational safety.

Abstract in English:

There is potential to improve corrosion resistance of AA7085 aluminium alloy by adding ultra-high temperature ceramic particles such as TiB2 and by using better T6 ageing conditions. AA7085 composites with 3–9 wt.% TiB2 particles were fabricated by the stir-casting method. T6 heat treatment of 525 °C solutionising, then artificial ageing at 230 °C for 10 hours was performed. Hardness assessment, 3.5 wt.% NaCl immersion corrosion for 24 hours, 48 hours and 72 hours, and Optical microscopy and SEM analysis studies as indicates the fine distribution of TiB2 particles. The AT9 sample achieved a maximum hardness of 122 HV, about 35% higher than the base AA7085. The lowest corrosion rate was observed for the AT9 composite at 230 °C ageing rate of 0.12 mm yr-1 at 72 hours. TiB2 particles inhibited pit initiation and promoted the formation of an Al-rich passivation layer. At higher ageing, pitting was observed to increase due to the reduction of over-ageing precipitates. The AA7085 composite reinforced with 9 wt.% TiB2 and artificially aged at 230 °C improved the corrosion resisting behaviour. The TiB2-Al matrix interface and the formation of a dense passivation layer are the key mechanisms for the enhanced corrosion resistance process.

Abstract in English:

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.

Abstract in English:

Bismuth has become one of the most promising anodes for lithium-ion batteries (LIBs) due to its suitable operating voltage and high volumetric capacity. However, the inevitable volume expansion of bismuth during the charge/discharge cycling process of lithium-ion batteries can lead to severe capacity fading and eventual battery failure. Herein, Bi-Bi2O3/C composite materials were prepared using a combination of solvothermal and calcination methods, and a series of characterization tests were conducted to investigate the effects of different secondary calcination times on the microstructure, composition, electrochemical properties, and the internal structural evolution during the initial charge/discharge cycle of the composite materials. In situ synchrotron radiation small angle X-ray scattering (SAXS) was employed to reveal the multi-level nanostructure evolution of Bi-Bi2O3/C electrode materials during charge/discharge processes. The present work reveals that these SAXS findings provide some new insights into the theoretical mechanism for the development of LIBs.

Abstract in English:

Accurate fatigue-life prediction under variable-amplitude loading (VAL) is critical for damage-tolerance assessment. This study presents a systematic comparative analysis of experimental data and numerical predictions of crack propagation in SAE-AMS 7475-T7351 alloy. NASGRO, AFGROW, and CRACK 2000 were employed to simulate standardized spectra (TWIST, FALSTAFF) and an actual commercial aeronautical load history, focusing on the calibration of Wheeler, GW, and MGW retardation models. The results demonstrate that calibration parameters (e.g., Rso) are highly spectrum-dependent. Physical analysis revealed that underloads attenuate retardation in the TWIST spectrum but are ineffective in the FALSTAFF spectrum. Discrepancies between the software packages, even with identical parameters, were attributed to varying ΔKth implementations.

Abstract in English:

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.

Abstract in English:

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.

Abstract in English:

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.

Abstract in English:

Equiaxed and rounded pore cellular metals with five different size ranges based on an aluminium-silicon alloy were fabricated by a soluble particle infiltration technique, in order to evaluate and compare their energy absorption capacity under impact and quasi-static compression. Under compression, the equiaxed cellular metal with the smallest pore size (4-4.75 mm) recorded the highest energy absorption (4.9 MJ/m3). In addition, the equiaxed pore cellular metals exhibited an energy absorption capacity 68.2% higher than that of the rounded pore ones. Under impact, for a standard strain of 9.8%, the highest energy absorption capacity was presented in the equiaxed cellular metal with the largest pore size (9.5-11.2 mm). In turn, the energy absorption in equiaxed pore cellular metals was 53.1% higher than that of the rounded pore ones. Cellular metals of both pore shapes showed a higher energy absorption capacity under impact. Therefore, it is concluded that this property varies depending on the shape and size of the pore, but also with the deformation rate.

Abstract in English:

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).

Abstract in English:

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.

Abstract in English:

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.

Abstract in English:

In this work, CeO2 nanoparticles were synthesized via the chemical precipitation method. With this objective, two distinct surface functionalization methodologies were applied: the first one uses anionic surfactant (SDS), and the second one uses hexadecanoic acid (C16H32O2). During the development of this work, nanostructured films were obtained via direct mixing and the solvent evaporation method (in situ and ex situ). This material was characterized via thermogravimetry (TGA), differential scanning calorimetry (DSC), field emission gun scanning electron microscopy (FEG-SEM), infrared absorption spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD). By XRD, when there is adequate incorporation and dispersion of nanoparticles, the characteristic peaks of the CeO2 crystalline planes are observed in the nanocomposites, and by SEM, their microstructures are evaluated to verify the dispersion. The results obtained showed that the synthesis protocols tested for the intended nanocomposite, with in situ or ex situ functionalization, were satisfactory. According to these results, it was possible to observe the agglomeration of nanoparticles without functionalization and confirm the nanometric scale for CeO2 nanoparticles synthesized without functionalization and with in situ functionalization (SDS), and their diameters were between approximately 10 and 15 nm. Additionally, for the PMMA powder, the Tg was 114 °C, whereas for the nanocomposite films, it averaged 53 °C, suggesting that the solvent acts as a plasticizing agent in the studied samples, thus reducing the Tg value. However, when samples obtained from the ex situ protocol by phase transfer with palmitic acid were analyzed, uncertainties were found regarding the adequate dispersion of CeO2 nanoparticles in PMMA, with in situ functionalization by SDS being the most promising.

Abstract in English:

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.

Abstract in English:

In order to develop high-performance electrode materials for electricity storage applications, novel composite designs that integrate many functional components in an efficient manner must be developed. Titanium dioxide (TiO2) nanofibers, reduced graphene oxide (rGO), and nickel oxide (NiO) nanosheets were effectively combined to create ternary nanocomposites in this work using a simple fabrication technique. Using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), the composites' structural, morphological, and electrochemical characteristics were thoroughly studied. Raman spectroscopy revealed the successful reduction of graphene oxide, while XRD examination proved the crystalline phases of anatase TiO2 and cubic NiO. The hierarchical nanostructure with TiO2 nanofibers wrapped with rGO sheets and enhanced with NiO nanosheets was seen in SEM pictures. The electrochemical performance of the TiO2/rGO/NiO composite electrode was slightly better than that of all three materials. The potential of multi-component nanocomposites for cutting-edge energy storage devices is made apparent in these studies.

Abstract in English:

This study investigates the influence of Severe Surface Mechanical Treatment (SSMT) on the AA5052 aluminium alloy, widely used in marine and structural applications. Using a Taguchi L9 orthogonal array and a TOPSIS-based multi-response optimization, the ideal SSMT condition (6 mm ball diameter, 1000 rpm, 30 min) was determined. The optimized treatment yielded significant property improvements: surface hardness increased by 48.5% (from 130 HV to 193 HV) and tensile strength improved by 21.5% (from 492 MPa to 598 MPa), achieving a surface roughness of 1.606 μm. Microstructural analysis (XRD/TEM) confirmed the underlying cause: grain refinement from 140.5 μm to 40.5 μm, increased dislocation density, and the formation of compressive residual stresses. These changes translated into enhanced durability. Electrochemical testing in 3.5% NaCl showed a 72% reduction in corrosion rate (from 0.45 mm/year to 0.126 mm/year), indicated by a lower corrosion current density and improved passive film stability. Additionally, the wear rate decreased by 76.5%, and hydrophobicity improved significantly (contact angle increased from ~73° to ~121°). Overall, the optimized dual-rotating SSMT system is a scalable and sustainable method for simultaneously enhancing the strength, wear, and corrosion resistance of AA5052.

Abstract in English:

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.