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Herein stacked layers of Nb2O5 coated onto Al substrates are fabricated as microwave resonators. Structural and morphological analyses on these stacked layers have shown the amorphous nature of growth of the stacked layers. Electrically, the resonators showed negative capacitance effect accompanied with series and parallel resonance at three well -distinguished notch frequencies. Additionally, the resonators exhibited bandstop filter characteristics with notch frequency ( f n) centered at 1.05 GHz, return loss ( R L) value of 9.0 dB and voltage standing wave ratios ( V S W R) of 2.12. To enhance the performance of the Nb2O5 microwave resonators, platinum nanosheets of thicknesses of 50 nm were inserted between layers of Nb2O5. Platinum nanosheets successfully decreased the surface roughness and increase the electrical conductivity by five orders of magnitude. Pt nanosheets additionally improved the values of f n, S 11, R L and V S W R to 1.16 GHz, 0.039, 30.3 dB and 1.12, respectively. The features of the microwave resonators comprising Pt nanosheets in its structure are promising for using them in communication technology.

The influence of polyacrylamide and multi-wall carbon nanotubes as binders for the granulation process for iron ore sintering was investigated in conditions of high proportions of ultrafine (< 0.150 mm). The binders were added to the sintering mixtures composed of 20 and 40 wt.% pellet feed and then subjected to granulation tests in an HPS laboratory scale route. The granules obtained were analyzed by particle size, shatter test (degradation), and cold permeability after granulation, degradation, and drying. A decrease in the granules’ size with the addition of polyacrylamide was observed due to decreased granulation efficiency, leading to low cold permeability of the granules. Adding nanotubes dispersed in burnt lime resulted in the improvement of the granulation process, presenting larger, more resistant and more permeable (before/after degradation) granules. After drying, the bed permeability of granules produced using polyacrylamide or nanotubes decreased significantly, pointing to low performance in the sintering dry zone.

Calcium hexaluminate (CA6) presents a wide application in high-temperature thermal insulation. Despite the high porosity levels achieved, the use of carbonated precursors in its synthesis inevitably produces CO2 as a by-product. CA6 was produced by combining different sources of alumina (α-Al2O3 and ρ-Al2O3) and lime (CaCO3, Ca(OH)2, and CaO) in aqueous suspensions that were cast and sintered to evaluate these routes on its physical properties. The products attained after sintering at 1550 and 1600 °C were characterized for crystal phases, real density, particle morphology, uniaxial compressive strength, apparent porosity, and pore size distribution. Part of the samples sintered at 1600 °C was subjected to a thermal shock test and was then evaluated for residual strength under diametrical compression, apparent porosity, pore size distribution, and flexural elastic modulus. The CA6 samples produced from α-Al2O3 presented lower pore fraction and higher mechanical strength and modulus of elasticity. The superior properties of the materials produced with α-alumina were maintained after thermal shock. The acicular geometry of the CA6 particles is related to their excellent thermal shock resistance and mechanical performance. The results indicated a more environmentally friendly system produced from α-Al2O3-CaO for industrial applications of high-temperature thermal insulation resistant to thermal shock damage.

The effect of ammonium bicarbonate (AB) and polyethylene wax (PW) on the physicochemical properties of macroporous biphasic calcium phosphate bioceramics (BCPs) processed by space-holder technique was investigated. BCP powder was mixed with AB and PW and, then, uniaxially cold-pressed at 300 MPa. AB and PW were eliminated by heat treatment at 170°C for 2 hours or 550°C for 4 hours, respectively. Subsequently, the samples were air-sintered at 1070ºC for 2 hours. The results revealed that AB is more attractive than PW due to its lower degradation temperature, which has avoided the formation of undesirable phases. In addition, it favored an adequate consolidation of the particles with the formation of sintering necks that provided a better mechanical resistance to handling. The samples with AB also presented the formation of uniformly distributed macro and microporosity in great extension, which is shown by literature as a fundamental combination to stimulate cells/scaffold interaction.

In this study, the surface of ZL104 was ultrasonically rolled (USRP) to provide better overall mechanical properties and corrosion resistance. USRP experiments were conducted on the surface by setting different parameters to improve the performance of ZL104 after strengthening. The results of the gradient residual stress test showed that the specimen with parameter 350N, 4-pass had 95.5% increase in residual stress and better fatigue resistance. The corrosion resistance of the specimen with a parameter of 500N, 3-pass was superior to that of the original specimen, with an increase of about 50%. The surface roughness test results showed that the surface roughness was reduced by about 38%-50% after USRP treatment. Meanwhile, the microstructure (OM, SEM) results showed that the surface grains were refined and the hardness increased from 105.45HV to 197.61 HV after USRP processing, and the properties were optimized.

Aluminium Metal Matrix Composites (AMMCs) reinforced with a particulate form of reinforcement have emerged as a replacement for monolithic alloys in various engineering industries due to their superior mechanical properties and customizable thermal and electrical characteristics. Silicon Carbide (SiC), is renowned for its high-temperature strength, hardness, wear resistance, excellent oxidation resistance, chemical resistance, low thermal expansion, high thermal conductivity, and compatibility with aluminium alloy find extensive utilization in Shipbuilding industries. The necessity for joining AMMCs arises in numerous engineering applications. Friction Stir Welding (FSW) emerges as one of the most fitting welding processes for joining AMMCs reinforced with particulate forms of ceramics without compromising their superior mechanical properties. This study endeavours to establish regression models predicting the Ultimate Tensile Strength (UTS), Percent Elongation (PE), and Weld Nugget Hardness (WNH) of friction stir welded AA6092 matrix composite reinforced with Silicon Carbide particles (SiC). The models correlate significant parameters such as tool rotational speed (TRS), welding speed (WS), axial force (AF), and percentage of SiC reinforcement in the AA6092 metal matrix. Statistical software Design Expert, along with analysis of variance (ANOVA) and student’s t-test, is employed to validate the developed models. It is observed from the investigation that these factors independently influence the UTS, PE, and WNH of the friction stir welded composite joints. The developed regression models are optimized to maximize the UTS and WNH of friction stir welded AA6092/SiC composite joints.

The growth of the oil and gas industry implies an understanding of corrosion and ways to mitigate pipeline failures. The objective of this research is to evaluate the propagation of localized corrosion induced by flow in different concentrations of sodium chloride and in the presence of corrosion inhibitor, associated with the wall shear stress. The API X65 steel specimens were drilled, with the purpose of simulating corrosion pits, and coupled to a modified ASTM G170 rotating cage.The experimental conditions were: (1) desaerated medium in the presence of CO2 under 5 bar, 120°C and concentrations of 0.1% or 10% sodium chloride; (2) aerated medium without CO2 at 40°C, without or with corrosion inhibitor. To evaluate the shear stress, Computational Fluid Dynamics (CFD) was used to understand the distribution on the surface of the samples. The results showed that the chloride concentration influenced the formation of the FeCO3 film and the corrosion rate. Furthermore, it was observed that the variation in diameter was more pronounced for the pits that had the smallest initial diameter, in all conditions evaluated. The highest values of diameter variation did not correspond to the highest values of shear stress imposed on each artificial pits.

Nowadays, few studies have reported on the sensitivity of thin films of Al-doped ZnO to ozone. This gas can become harmful to health depending on its environmental concentration. This work presents the sensor response to ozone gas of pure ZnO and Al-doped thin films, prepared by sputtering with varying deposition times. Ceramic targets prepared by SSR, compacted at 65MPa, sintered at 950°C, with densities ranging from 74-97% of the theoretical density, depending on the dopant content were used. The films showed an increase in thickness with deposition time and a preferential growth in the (002) plane of the ZnO structure. Slight changes in the band gap value occurred with increasing Al, whose presence in the ZnO lattice was confirmed by XPS. The sensitivity results to ozone showed that the performance of the films decreased with the Al-doping, which could be attributed to the defects formation related to oxygen in the lattice during Zn-Al substitution or to the greater densification of the films. Although the results showed a decrease in the sensor properties, all films are sensitive to ozone, including the low concentrations of 50 ppb, a limit considered for a maximum daily average for human exposure, established by the WHO.

The innovative work shows a new strategy to modify the physicochemical properties of medicines and improve patients' lives. The mechanochemical synthesis and characterization of the first Norfloxacin nanocrystal are described. In recent decades, nanotechnology has gained significant attention in the scientific field through the study of the design, formation and application of materials at the nanoscale level. In the pharmaceutical sector, nanotechnology has been the focus of studies on systems that allow increased bioavailability. The present work investigated the formation of pharmaceutical nanocrystals. Nanocrystals are crystalline nanoparticles ranging in size from a few nanometers to 1,000 nm, composed of 100% of the drug and stabilized by surfactants or polymeric stabilizers. They have a safe formulation and are well tolerated compared to conventional medicines. The drug used in this study was Norfloxacin, a broad-spectrum antibiotic that has low bioavailability. Several nanocrystallization techniques are found in the literature, among which the mechanochemical method stands out. Mechanochemistry is an approach that allows the reduction of particle size through the mechanical energy provided in the reaction medium. Thus, it was possible to obtain nanomaterials and explore the influence of surfactants in controlling the particle size and morphology of the materials obtained.

This study presents the synthesis and in-depth evaluation of a novel Tin(IV) oxide/reduced graphene oxide (SnO2/rGO) nanocomposite developed as an electrode material for advanced electrochemical supercapacitors. Utilizing a scalable synthesis method with optimized parameters, the resulting nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), revealing its well-defined morphology, crystal structure, and composition. Comprehensive electrochemical assessments, including galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV), demonstrated that SnO2/rGO exhibits superior performance metrics compared to pure SnO2. Notably, at a current density of 1 A g−1, the SnO2/rGO nanocomposite achieved a specific capacitance of 140 F g−1, surpassing the 133 F g−1 of pure SnO2. These findings highlight the SnO2/rGO nanocomposite's potential to significantly enhance energy storage capabilities, making it a promising candidate for applications in electric vehicles, portable electronics, and sustainable energy systems.

Cryogenic treatment enhances the properties of cutting tools. This study investigates the effects of shallow and deep cryogenic treatments to TiAlSiN coated tungsten carbide tool used in end milling of maraging steel C300. Experiments are conducted in a three axis CNC vertical milling machine at various spindle speeds using TiAlSiN coated tool without cryogenic treatment (UCT), shallow (SCT) and deep (DCT) cryogenically treated coated tools. The surface finish obtained during milling of slots, built-up edge of tools and the tool wear are investigated and compared. With an increase in spindle speed, SCT tool showed an improvement of 13.3% with UCT and 33.5% with DCT. Formation of built-up edge on the cutting tools are also evaluated and compared. Tool wear is quantified, in which SCT tool showed lowest tool wear in comparison with UCT and DCT tools.

Residual stresses exist intrinsically in any manufactured or processed material, significantly influencing its mechanical properties. Shot peening enhances fatigue life by introducing compressive residual stresses at the surface, however, the beneficial effects may be reduced under external loads. This study investigates the behavior of surface residual stresses induced by shot peening in API 5L X80 steel. Specimens underwent tensile monotonic loading cycles below the yield strength, incrementally increasing the load until reaching the yield limit. Residual stresses were measured using the X-ray diffraction by sin2ψ method, revealing a progressive stress relief of compressive residual stresses field induced by shot peening. The development of tensile residual stresses was observed following the monotonic tests. Loads below yield stress were able to completely reverse compressive stresses to tensile stresses. A correlation was observed between residual stresses and magnetic Barkhausen noise, suggesting it as a potential method for analyzing residual stress behavior qualitatively in shoot peened steel samples.

Alum sludge (AS) from water treatment plants is an abundant, non-toxic residue with high Si and Al contents. These characteristics make it an ideal precursor for zeolite synthesis, not only reducing the environmental impacts from AS disposal but also adding value to the waste by promoting its reuse. Herein, we propose a route to prepare zeolitic materials from AS, aiming for its application as a component of slow-release fertilizers, using mild conditions and cost-effective hydrothermal synthesis. X-Ray Diffraction revealed the formation of sodalite (Na-SOD) in short times (5-10 h) and moderate temperatures (100-120ºC), with sodium silicate addition favoring Si-quartz consumption and zeolite crystallization, without a fusion step. The Na-SOD showed a desirable cation exchange capacity, reaching 117 mg g-1 for K+. A K-SOD fertilizer was then prepared with an average 490 nm size, 2 m2 g-1 BET surface area, and slow-release behavior. Incubation in soil confirmed that Al was inactive in K-SOD and did not immobilize phosphate, in addition to promoting high K+ availability. The results support the potential of AS reuse for application in agriculture as an efficient and sustainable fertilizer.

This work evaluates how adding cetyltrimethylammonium bromide (CTAB) in the synthesis affects the physical and chemical features of Ni/CeO2 catalysts. The samples were characterized by the Rietveld refinement from X-ray diffraction (XRD) and showed a decrease in the crystallite size and an increase in the microstrain from 5.9 to 7.5 x 10-3. Nitrogen physisorption analysis was used to obtain the pore size distribution by the BJH method, varying the pore size between 8 and 12 nm. Raman spectroscopy was employed to confirm the fluorite structure arrangement of ceria and the number of vacancies in the bulk phase, where the ratio from vibrational modes related to defects and oxygen vacancies increased from 0.488 to 0.516 ratio. With the spectra obtained from X-ray photoelectron spectroscopy (XPS), it was possible to observe the distribution of metals on the surface of the samples and their oxidative states, providing clues about the quantity of vacancies. Samples with higher concentrations of CTAB obtained higher values of Ce3+, reaching a 0.45 ratio on the surface. The scanning electron microscopy (SEM) analysis showed that the addition of CTAB formed more irregular shape grains, reaching 20 μm of medium size for all the samples.

Piezoelectric ultrasonic sensors used in Structural Health Monitoring (SHM) systems are usually attached to components by using adhesives with intrinsic properties that end up affecting their frequency-response. In this work, the electromechanical impedance of sensors attached to an aluminum sheet with three different epoxy resins was monitored during curing. Impedance change indexes (CIs) were calculated and compared with cure degree estimations from Differential Scanning Calorimetry (DSC). Results show that resonance frequencies were displaced by up to 30 kHz, and amplitudes changed considerably during the curing process of the selected resins. Results indicate that certain CIs show a high positive correlation value (R=0.96) with DSC data, and could therefore be used in practical applications to evaluate the curing status of the adhesive in SHM applications.

A versatile nature of polyurethanes allows for the modification of thermal, mechanical, and chemical properties, making them promising candidates for medical applications. This study focuses on the synthesis, characterization, and biocompatibility evaluation of a novel poly (L-co-D,L-co-lactic acid-co-Caprolactone)urethane (PLDLA-PCL-PU) material derived from L-lactide, D,L-lactide, polycaprolactone-diol (PCL-diol) and 1,6-hexamethylene diisocyanate (HDI). This research performs a meticulous two-stage synthesis process, ultimately leading to the formation of PLDLA-PCL-PU through polymerization of the prepolymer (PP) and HDI. The confirmation of successful synthesis and the characterization of PLDLA-PCL-PU was done by FTIR-ATR, and 1H NMR. As evidenced by XRD, the amorphous nature of PLDLA reduces the degree of crystallinity in PLDLA-PCL-PU. Thermal decompositions, as well as the associated thermal events, were investigated using TGA and DSC. The biocompatibility of the material was evaluated using human mesenchymal stem cells. These assays reveal a notable enhancement in cell metabolic activity and proliferation when in contact with polyurethane membranes. By combining the properties of polyurethanes with the custom design of PLDLA-PCL-PU, this research strives to contribute with the advancement of biomaterials that promote tissue regeneration.

The properties of a hot-deformed component can be enhanced by planning its forming process within the desired thermal processing-parameter windows associated with dynamic recrystallization (DRX). In order to determine the windows of 40Cr10Si2Mo steel, hot compression tests were employed within the deformation conditions of 1173-1398 K and 0.01-10 s-1. Following this, the hot processing maps, which distinguished the parameter domains with stable plastic deformation, were established according to the stress-strain data. The DRX domains were further identified within the stable deformation domains and represented as a map illustrating the deformation mechanisms of this steel. The deformation activation energy, which describes the forming difficulty degree of material, was calculated, and its evolution map with parameters was constructed. The deformed microstructures were characterized utilizing a scanning electron microscope (SEM) to verify the deformation mechanism map. An enhanced processing map which superimposed the activation energy map over the deformation mechanism map, was developed. The resulting map facilitated the determination of optimal windows that ensure DRX mechanism and lower activation energy. The optimal windows for 40Cr10Si2Mo steel were finally obtained as: 1322-1398 K & 0.016-0.35 s-1 and 1344-1380 K & 0.035-0.126 s-1.

The medical research community continues to search for effective technologies to treat diseases such as cancer, with photodynamic therapy (PDT) being a notable advancement. PDT combines light, oxygen, and a photosensitizer (PS) to target diseased cells. This study addresses the advancement of PDT in medical science for the treatment of diseases such as cancer, emphasizing the development of an efficient PS with desirable properties such as non-toxicity in the dark, high singlet oxygen yield, and selective targeting capabilities. Zinc oxide nanoparticles (NPs-ZnO), recognized for their unique catalytic and photochemical properties, are emerging as a potential next-generation PS for PDT. The research uniquely employs an eco-friendly synthesis approach using Glycine max (soybean) extract, in line with green chemistry principles. This novel method not only ensures the synthesis of NPs-ZnO, but also promotes environmental sustainability. The synthesized NPs-ZnO were evaluated for their ability to generate reactive oxygen species (ROS), which are essential for the degradation of methylene blue dye and serve as a proxy for their efficacy in PDT. In particular, NPs-ZnO synthesized using zinc acetate, zinc chloride at 180°C, and zinc nitrate at 100°C were identified as the most promising candidates for PDT applications. Their significant performance in ROS generation underscores the potential of these nanoparticles to enhance the efficacy of PDT in cancer treatment, paving the way for further research and development in this promising field.

In this study, cellular spacing, porosity and corrosion of 1050 aluminum alloy subjected to the different levels of Gamma radiation was examined using a Gammacell Co-60 type irradiator, with activity of 16.13 TBq and dose rate around 6.98 Gy/min. Samples were extracted from an aluminum ingot, which was obtained with directional solidification apparatus. This upward directional solidification technique allowed obtaining of aluminum samples under different conditions of cooling rates. Firstly, cooling rates were determined during solidification experiment and then correlated to the cellular spacings and porosity content. The experimental results pointed out that cooling rates exerts a strong effect on the microstructural patterns and porosity formation. Laws have been determined, indicating that increase in cooling rates favored a refinement effect on as-cast microstructure and a decrease in porosity content. Furthermore, measurable effects of different levels of the Gamma radiation on the microstructure, porosity and corrosion for samples of 1050 aluminum alloy, were determined. The experimental results show that Gamma radiation has favored changes in cellular spacings, porosity formation and corrosion behavior. From this results, one can conclude that coarser microstructures, porosity formation and corrosion are favored by prolonged thermal annealing caused by temperature field generated during Gamma radiation exposure. On the other hand, even after the exposure to different levels of Gamma radiation, the microstructure and porosity observed in as-cast samples are still strongly dependent of the cooling conditions.

The work evaluated the nucleating effect of nanometric zirconia (Zr-NP), obtained by the green sol-gel synthesis route using Euclea natalensis root extract as a reductant, in the low-density polyethylene (LDPE). The Zr-NP was characterized with x-ray diffraction (XRD) and transmission electron microscopy (TEM) which confirmed the presence of Zr-NP in the cubic crystalline phase with an average particle size of 6.73 nm. The Zr-NP was incorporated into the polymeric matrix by solubilization in concentrations ranging between 0 wt% and 6 wt%. Non-isothermal DSC analyzes demonstrated that a small addition of 1 wt% changes the degree of crystallinity from ~23% to ~56%, an increase of ~137%. The addition of Zr-NP also caused a small increase in crystallization and melting temperatures, and a large increase in the total crystallization time of LDPE.

TC4 (Ti6Al4V) alloy is widely used in aerospace, medical equipment, food industry and other fields. Laser powder bed fusion (LPBF) technology has a short production cycle and high precision for formed parts, providing new ideas for the manufacturing of complex structures such as aerospace and having great development prospects and manufacturing advantages. This paper took the TC4 heat dissipation structure prepared by LPBF technology as the study object and established a numerical simulation model to analyze the temperature field changes of the TC4 heat dissipation structure prepared by LPBF. By adopting the annealing heat treatment process, it was found that with the increase in annealing temperature and holding time, the microstructure coarsened, the hardness first increased and then decreased, and the corrosion resistance improved. Among them, when the annealing temperature was 900 °C, and the α' phase was basically transformed into α phase, and the content of β phase increased. The grains and structure of the heat dissipation structure were uniform, and the most significant was in the near inner-pore area. At this point, the hardness value significantly decreased, and the difference in hardness around and outside the heat dissipation hole was 12.42 HV0.2.

Microbiologically influenced corrosion is a common problem in the oil and gas industry. It is a type of corrosion induced by biofilm-forming microorganisms such as sulfate-reducing bacteria which produces corrosive compounds as a product of their respiration. The most indicated treatment for the issue is the use of biocides, chemical substances used to kill microbes. However, biocides are corrosive to many materials, making their selection a problem. The 2,2-dibromopropanediamide (BDNPA) is a biocide used to control the growth of a wide range microorganisms. There is a literature gap for selecting materials that can be used with DBNPA Biocide without risk of corrosion. Hence, this research is dedicated to investigating the corrosion behaviour of commonly used alloys in a DBNPA solution. This work evaluated 11 alloys commonly used in the laboratory for the manufacture of instrumentation piping. Anodic polarization tests and 30 days immersion tests were carried out in a 100% DBNPA solution at two temperatures (25 and 40 ºC). Among the analysed alloys, only 4 were approved by the tests in all tested temperature ranges (Titanium Grade 2, Hastelloy C276, Inconel 625 and Superduplex Steel SAF 2507). These alloys did not present a localized corrosion process in any of the 30-day immersion tests, in addition, they obtained a significant passivation domain in the anodic polarization test at 40 ºC. The remaining alloys (AISI 304, AISI 316, AISI 317, AISI 321, AISI 347, Monel 400) were not approved in all temperature ranges tested for transport and storage of 100% BDNPA biocide solution.

Titanium dioxide (TiO2) is an n-type oxide semiconductor, where the electron donors are usually associated with oxygen vacancies and interstitial titanium ions, whereas quinoline derivatives (QD) are usually p-type semiconductors with light emission in the blue range. We report a broad emission band centered at 485 nm, and temperature induced electrical properties of the QD 4-(6-(diethylamino)-4-phenylquinolin-2-yl)benzoic acid and TiO2 films. The combination of QD with TiO2, both layers in the form of thin film, forms a heterostructure in a very convenient format for integration in optoelectronics. Due to the techniques used for film deposition, both sort of films present defects, which are responsible for the electrical characteristics. The dominant level for TiO2 is located about 760 meV from the conduction band bottom, inside the bandgap, whereas for the QD film the activation energy is about 328 meV. Both levels show up for a range above room temperature. In the first case, it suggests the second ionization level of oxygen vacancies (VO2+) or the third ionization level of interstitial titanium ions (Ti3+), considering that both are electron donors, whereas in the case of QD it suggests a mechanism of small polaron tunneling (SPT).When combined as a heterostructure and explored under transport profile perpendicular to the films (transverse contacts) it leads to current-voltage (I-V) rectifying behavior similar to a p-n junction, which is evidence of the p-type-like electrical behavior of the QD, even though this I-V behavior may be destroyed for repetitive I-V measurement, which seems to be related with aging and the presence of defects at the heterostructure interface.

The aim of this study was to assess the impact of rail metallurgy, focusing on segregations and chemical composition, and welding parameterization on the quality and susceptibility of welds to defects and failures induced by mobile flash butt welding (FBW). Ten welds were performed using two different welding programs, with varying heat input, on premium rails sourced from the same batch. The welds underwent full metallurgical characterization of the weld and HAZ, including hardness profile, mechanical testing, and micrographic analysis of the head, web, and foot regions. The results showed that both the HAZ dimensions and the hardness profile are influenced by weld parameterization. All welds fabricated by the lower heat input program, small islands of martensite and retained austenite (MA) were observed only in the foot region, close to the weld line. From the higher heat input program, only one weld showed islands of MA. Localized chemical analysis indicated that the formation of these islands is linked to microsegregation, especially of Mn and Cr present in the rail.

The present study features analytical and experimental results of AA5754/DP600 dissimilar joints produced by the refill friction stir spot welding of 1.5-mm-thick sheets. The selection of proper parameters for this process, such as tool rotational speed (RS), welding time (WT), tool plunge depth (PD), welding force (WF) and backing plate material played an important role in assuring weld strength. In this work, experimental tests were carried out based on the welding conditions according to Taguchi method, in order to determine optimal welding parameters and investigate the effect of those in the joint’s mechanical properties. Analysis of variance (ANOVA) was also applied to determine the individual importance of each parameter on the lap shear strength (LSS). The results showed that the use of a backing plate with high conductivity during the welding process is a critical factor for control the formation of intermetallic layer on the interface of the joints and consequently increase the mechanical properties of the joints. Additionally, the results based on lap shear strength indicated that tool rotational speed was the parameter with the largest influence on the joint shear resistance. In contrast, DT was shown to have no significant influence on the joints performance for the selected range tested.

In plasma nitriding of cutting tools, edge embrittlement can result from both, deepest layer, and grain boundaries precipitation. Overheating and surface charge density concentration in Direct Current Plasma Nitrided (DCPN) can be reduced through an indirect source of plasma, called Active Screen Plasma Nitriding (ASPN). The removal of the oxide layer from previous processes, such as heat treatment, is required in DCPN samples. This metallographic preparation can be a challenge in more delicate locations, such as on edges. This preliminary step is not usually described in studies comparing DCPN with ASPN. In the present work, a special pre-nitriding procedure aims for edge integrity and equivalent surface state at the top and the flank of AISI M2 samples. Under standard temperature (500°C) and atmosphere (2.5mbar, N 2 / H 2 : 25 / 75), ASPN and DCPN were conducted for 2 and 4 hours, respectively. Edge cross-sections were analyzed in an Olympus GX-51 optical microscope (OM) and in a Carl Zeiss EVO MA 15 Scanning Electron Microscope (SEM). ASPN was effective in reducing embrittlement caused by grain boundary precipitation at a plasma nitrided edge.

This study investigates the incorporation of hafnium (Hf) into polyurethane foams (PUs), an underexplored area in polymer materials research. The synthesis of Hf-containing PU foams was conducted, and their characterization was performed using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), optical microscopy (OM), and dynamic mechanical analysis (DMA). The results revealed a significant increase in the stiffness of PU foams due to the potential formation of hafnium isocyanate. Quantitative values obtained through DMA tests demonstrated an approximate increase of 95.97% for PU Hf 0.5% and 342.72% for PU Hf 3%, compared to the sample without Hf. These data highlight the influence of hafnium on enhancing the mechanical properties of polyurethane foams.

Conjugated polymers have attracted considerable attention to the organic electronics field, due to their properties and a variety of potential areas of application, such as solar cells, OLEDs, sensors, and transistors. In the sensor area, the study of chloroform gained prominence due to its toxicity and effects on the human body, such as damage to the liver and kidneys. This work aims to study thin films of P3DT in different concentrations, perform their optical, morphological, and electrical characterization, and verify their applicability as chloroform sensors. The thin films and devices are characterized using various techniques: optical characterization is performed through UV-vis spectroscopy, morphological characterization is performed through optical microscopy and electrical characterization is performed in direct current by studying the current vs. voltage curves. Electrical measurements of current vs. time are also performed in order to verify the electrical response of the active layer when exposed to a saturated chloroform atmosphere. Characterization shows expected results, similar to other P3ATs, while gas response initially shows a release in trapped charges, increasing the current, however, as the measure is repeated, the current started to decrease when exposed to the current, caused by a swelling in the polymer’s chain.

The corrosion resistance of Inconel 625 processed by L-DED additive manufacturing using virgin and reused powders was investigated to optimize the cost-effectiveness of the process. Samples were manufactured under a controlled argon atmosphere. Feedstock and samples were characterized by optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and rheology analysis. Corrosion resistance was investigated by cyclic polarization and electrochemical impedance spectroscopy in NaCl 3.5% media. Rheology accused a slight decrease in powder flowability with reuse, but no further appreciable powder degradation was observed. Samples developed a dendritic microstructure with Mo- and Nb-rich Laves phase in the interdendritic region. Samples processed with reused powder were found to have a high content of oxides, which accounted for a slightly inferior impedance and reduced the charge transfer resistance by nearly 50%. Specimens had an overall similar cyclic polarization, with the specimen processed with virgin powder having a slightly superior performance, with a 60mV more noble Ecorr and higher Rp, but similar Icorr. Samples presented uniform and pitting corrosion mechanisms, with pits being preferentially located in the Mo-depleted dendritic regions. In summary, the reuse of Inconel 625 powder processed under argon-controlled conditions was not considered to be significantly detrimental to the alloy corrosion resistance.

This study aims at showing the influence of transformation-induced plasticity (TRIP) on the residual stresses and magnetic permeability of AISI 304 stainless steels and the resulting effect on its fatigue performance. Samples were pre-strained to different levels of plastic deformation, and characterised through metallography, hardness, tensile testing, X-ray diffraction (XRD) and with the MWM®-array electromagnetic method. Fatigue tests were then conducted on these samples to obtain the S-N curves for each condition, and the resulting fracture surfaces were analysed using scanning electron microscopy (SEM). Residual stress distributions in martensite and austenite were significantly affected by the transformation, although in different ways, and this is thought to be the reason for the improvement in fatigue performance in samples with higher pre-deformation values. Magnetic permeability measurements corroborated XRD results and proved to be a useful tool for non-destructively determining martensite transformation distributions in manufactured components.

PEO/TiP fibers were obtained using the Solution Blow Spinning (SBS) apparatus and heat treated to produce TiO2 fibers. The morphological and structural characteristics were assessed using SEM and X-ray diffraction. The fibers, with a thickness of 12 μm, showed a change in crystalline structure with heat treatment. At temperatures as low as 800 °C, only the anatase phase was identified, while at 900 °C, both anatase and rutile phases coexisted. The addition of TiP to the polymer matrix reduced the initial breakdown temperature, and the DSC curves showed exothermic peaks due to the amorphous phase transition to TiO2/anatase. The fibers' photocatalytic capacity was tested, revealing that TiO2-fibers in the anatase phase achieved 97% degradation of Rhodamine-B dye in 40 minutes. The study found that the biocide efficacy of TiO2-fibers depends on their heat treatment. Fibers with anatase/rutile or pure rutile phases did not show significant efficiency. However, fibers treated at 600°C with pure anatase phase were more effective in eliminating E. coli and total coliforms. Finally, we can state that the TiO2 fibers obtained in this work using the SBS technique can be used to produce filters to purify water contaminated by pathogens dangerous to human health or even to purify the air.

Aluminum Hybrid Metal Matrix Composites (Al-HMMCs) are contemporary materials that blend aluminum with additional reinforcing elements to enhance their mechanical, thermal, and other properties. These materials find applications across various sectors including the aerospace industry, automotive sector, military and defence, marine industry, as well as manufacturing industries. In this research, AA6061, zirconium dioxide (ZrO2) and boron carbide (B4C) have been selected as the matrix and reinforcement materials. AA6061/ZrO2/B4C (Al-HMMCs) is manufactured using Ultrasonic-assisted stir casting. The process parameters of ultrasonic assisted stir casting were optimized with the help of Taguchi optimization technique. The melting temperature (700, 750 and 800 ºC), stirring speed (10, 15 and 20 minutes) and AA6061/xwt.%B4C/xwt.%ZrO2 ( 6, 8 and 10) are selected as input parameters for optimization. The reinforcements ZrO2 and B4C are weighed by equally sharing by wt.% The micro hardness was selected as response parameter and it was determined by using Vickers micro hardness tester. The L9 Orthogonal Array (OA) was employed for optimization of input parameters of ultrasonic assisted stir casting. Taguchi results showed that medium level of melting temperature (750 ºC), higher level of stirring speed (300 rpm), lower level of stirring duration (10 minutes) and medium level of wt.% of ZrO2 and B4C (8wt.%) were the optimized combination of input process parameters of ultrasonic assisted stir casting for fabricating AA6061 HMMC. The AA6061/xwt.%B4C/xwt.%ZrO2 (x = 0,4,6,8 and 10) HMMCs were manufactured by utilizing optimized process parameters. The micro hardness of AA6061/xwt.%B4C/xwt.%ZrO2 (x = 0,4,6,8 and 10) was determined. . From the obtained hardness tests, it was observed that the hardness of AA6061 HMMCs was enhanced up to addition of 8wt. % of B4C and ZrO2 and decreased the hardness while adding 10wt.% of B4C and ZrO2. The better AA6061/8wt.%ZrO2/8wt.%B4C HMMC undergone X-ray Diffraction Analysis (XRD) and Scanning Electron Microscope (SEM) testing to identify elements and examine the microstructure. The high peak of ZrO2, B4C and Al was obtained in 71.4, 35.68 and 37.81 2 theta values respectively. The SEM image of ultrasonic aided stir cast AA6061 based composite was confirmed the uniform distribution of zirconium di oxide and boron carbide reinforcements. There was no oxide formation on the surface of the stir casted AA6061 composites due to the execution of casting process in the inert environment. The casted AA6061/8wt.%ZrO2/8wt.%B4C surface of the composite exhibits no porosity occurrence due to the impact of usage of ultrasonic vibrator to prevent the formation of holes due to escape of unwanted gases. Subsequently, corrosion tests were conducted on the AA6061 HMMC in various corrosive environments such as NaOH, HCl, H2SO4, and NaCl to evaluate its electrochemical behavior. The surfaces of corroded specimens were analyzed using SEM and Energy Dispersive Spectroscopy (EDS). The research findings indicate that AA6061 composites exhibit the highest corrosion resistance when immersed in a NaCl medium. This enhanced resistance was attributed to the medium's lower corrosion potential, stronger charge transfer resistance (Rct), and lower double-layer capacitance (Cdl) compared to alternative environments. Additionally, SEM analysis illustrated that the incorporation of B4C and ZrO2 ceramics results in the formation of protective barrier layers, further enhanced their corrosion resistance. ZrO2 particles were attracted and neutralized the corrosive ions and electrons, thereby reducing corrosive activity on the AA6061 aluminium matrix.

Geopolymers are inorganic polymers obtained through the alkaline activation of aluminosilicates. Due to their cementitious properties, they are being studied as a sustainable alternative to Portland cement. Red ceramic waste (RCW), being a source of silica and alumina, can serve as a precursor for producing geopolymers. In this work, we evaluated the feasibility of producing geopolymers from hollow brick (HB) and hydrated lime, using only sodium hydroxide as an alkaline activator. The test specimens were prepared replacement HB by up to 30 wt% of hydrated lime, aiming to evaluate the compressive strength after 7 and 28 curing days of the geopolymer produced. The results showed that samples with 30 wt% of hydrated lime, achieved the highest compressive strength (11.26 MPa) after 28 days of curing, although all values found were above the limit established by Brazilian standards for modular geopolymer bricks. The results therefore show a sustainable and widely viable implementation alternative to reduce the environmental impacts caused by the production of Portland cement.

In this work, the asymmetrical rolling of 860 μm thick high-purity titanium (HP-Ti) strips is investigated. HP-Ti ultra-thin strips are produced in thicknesses ranging from 280 μm to 20 μm. The microstructure and texture evolution of HP-Ti ultra-thin strips were analyzed using electron backscattering diffraction (EBSD), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The raw strips have a homogeneous and equiaxed microstructure, containing some face-centered cubic (FCC) Ti laths. With a rise in rolling reduction, equiaxed grains change into deformation structures characterized by a high density of dislocations. The formation of an ultra-fine grained microstructure and the elimination of FCC-Ti laths come next. The influence of grain rotation and slip systems on the development of texture in ultra-thin strips during rolling reduction is illustrated through the analysis of {0002} pole figures and orientation distribution function. The tensile qualities of ultra-thin strips are correlated with their microstructure.

This work addresses the corrosion resistance of Riser steels used in submarine pipelines for oil production, making it crucial to evaluate the variables related to corrosion in the marine environment. Three types of wires with spheroidized, lamellar and discontinuous cementite microstructure were tested in 0.1M H2SO4 with and without the use of CO2, in addition to a different ambient temperature (80 °C). Thus, electrochemical tests, including OCP and linear potentiodynamic polarization, revealed the corrosion resistance of each material. The analysis of the polarization curves through Tafel extrapolation, obtained the current density, correlating with the potential of the sample in the medium, indicating the polarization resistance. The LC wires demonstrated greater resistance to corrosion (769.23; 2,544.79 and 4,790.87 Ω.cm2) compared to spheroidized cementite (502,40; 1,038.99 and 902.95 Ω.cm2) and, which, in turn, obtained lower resistance values in two of the solutions. The FeCO3 and FeSO4 salts were formed in different areas, including the most degraded ones identified by Raman spectroscopy.

This study focuses on the preparation and characterization of silver-doped calcium titanate (CaTiO3) photocatalysts for the degradation of Rhodamine B (RhB) dye. Utilizing a hydrothermal microwave-assisted method, efficient photocatalysts of pure CaTiO3 (CT) and 3% (CT3%) and 5% (CT5%) Ag-doped CaTiO3 were prepared. X-ray diffraction confirmed the orthorhombic phase of CaTiO3 with residual TiO2, more pronounced in the CT3%. Micro-Raman and FTIR spectra verified the presence of TiO2, while SEM images revealed distinctive morphologies. The band gap energy was lower in Ag-doped samples, particularly in the CT3% sample. Photocatalytic tests demonstrated superior RhB degradation with the CT3% catalyst. A 22 factorial design was used to determine the ideal condition for the photocatalysis. Photocatalysis with CT3% was efficient in toxicity removal, but stability tests indicated a decline in performance over multiple cycles. These findings suggest the potential of Ag-doped CaTiO3 as efficient photocatalysts for dye degradation.

Poly(3-decylthiophene) is a polymer with conductive characteristics due to its conjugated polymeric chain. With the search for new applications and improvements of these materials, in sensors, and OPVs, there is a great demand for deeper knowledge about them. This work aims to characterize the P3DT, through analysis of optoelectrical measurements. Using the drop casting technique, thin films were made onto solid substrates. The films were subjected to optical characterization by UV-Vis and optical microscopy. The electrical characterization was obtained by IxV curves and then measuring the photoconductivity through Ixt curves, with a solar simulator. With UV-Vis measurements, it was observed that the absorption of light in the visible spectrum reached a peak of 520 nm in the film, blue-shifted in the solution attributed to the differences in the organization of the polymer chains. The optical microscopy measurements indicate the formation of aggregates with a higher concentration of aggregates observed for the film obtained with a more concentrated solution. Finally, the photoconductivity measurements carried out obtained a positive response to the photo-excitation of the material due to exposure to light, with an increase in current in the film as the photo-exposure cycles were repeated.

Ti/Al/Ti laminated composite material is an ideal material for high-temperature parts and protective armor in the aerospace field because of its high specific strength and high temperature oxidation resistance. To improve the joint strength, the ultrasonic welding solid-phase joining technology is used to prepare Ti/Al/Ti laminated composites. The results show that the temperature, microstructure and microhardness distribution of the aluminum interlayer are uniform after welding. The recovery recrystallization behavior reduces the hardness of the aluminum interlayer during welding, while the microstructure and microhardness of the upper and lower titanium layers do not change significantly. The tensile shear failure positions of the joints are all located in the lower Al/Ti interface layer, and the highest tensile shear strength reaches 124.4 MPa (1200 W). At this parameter, the plastic constraint reinforcement effect is the most significant, the interface exhibits a small amount of vortex-like morphology, and the local area of the aluminum material melts below the equilibrium melting point. When the welding power reaches 1400 W, the upper surface of the weld is crushed, and the TiAl2 IMC phase precipitates in the Ti/Al interface region.

Superhydrophobic surfaces offer innovative solutions, particularly in water/oil separation systems, as they repel water and attract oil, enabling efficient separation. The study aimed to analyze coatings developed on galvanized steel and aluminum, regarding their wettability in saline water and diesel oil, aiming for applications in the oil and gas industry. Specimens underwent texturizing, in-situ growth of layered double hydroxide (ZnAl-LDH) film and modification with stearic acid (STA). Both LDH films exhibited similar binary hierarchical structures of hexagonal petals and micrometric flowers, interconnecting along the surface, forming pores that allowed for air entrapment after STA modification. CA for saline water exceeded 150º, and for diesel oil was under 10º, characterizing the coatings as superhydrophobic and superoleophilic. The coatings show promising potential for water/oil separation using recyclable substrates and a simple, low-cost, environmentally friendly process.

This academic article investigates the performance of dye-sensitized solar cells (DSSCs), which are affected by various defects like charge recombination, high impedance, and low power conversion efficiency due to complex physicochemical phenomena. The study explores different materials and processes to enhance DSSC performance, with a focus on photoanode development. Tin dioxide, tin chloride II dihydrate, copper oxide, boric acid, and sodium phosphate are utilized to fabricate the photoanodes. A thermal treatment at 450°C for 30 minutes precedes dye assembly on the photoanode surface. Results show that the tin chloride II dihydrate-modified photoanode outperforms others, achieving higher open-circuit voltage (0.50V), current density (9.58 mAcm-2), fill factor (0.37), and power conversion efficiency (1.77%). The study suggests that tin salt particles positively impact voltage, current, electron transport, and charge separation, enhancing overall cell performance. Charge recombination significantly affects power conversion efficiency and impedance, but accurately quantifying it remains challenging. Lower recombination levels favor efficiency, while higher levels reduce it.

Structural morphology, defects, compressibility and permeability properties studied by finite element analysis, selective laser melting technology and micromorphology, mainly to analyze the effect of porosity on the performance of porous skeletal scaffolds. The results showed that during the preparation process, there are construction errors. The designed structures were able to meet the requirements of cancellous and cortical bone in terms of compressive stress and elastic modulus. The compressive stresses of the diagonal cubic compact row and octahedron are more similar at the same porosity, the elastic modulus and compressive stress decrease with increasing porosity for three structures. In the hydrodynamic analysis, the maximum flow velocity appears in octahedron up to 0.001m/s. Permeability increases with increasing porosity for all structures. The maximum permeability was obtained at 75% porosity for all structures, the pressure drop for three structures at this porosity was most similar to that of natural bone (4.153 E3 N/m3).

The main objective of this paper is to produce an anodic layer of TiO2 rich in calcium, phosphorus, and magnesium using the anodizing technique known as micro-arc oxidation (MAO) on the Ti-25Ta alloy together with the incorporation of silver (Ag), copper (Cu) and zinc (Zn) metallic ions using different electrolytes. The structural changes and microstructures on the MAO surfaces were analyzed using the X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). The chemical composition to verify whether silver, copper, and zinc were incorporated via energy dispersive spectroscopy (EDS) and surface characteristics such as wettability and hardness of the coatings were also investigated. From the EDS mapping results, it is observed that the MAO process was effective in incorporating the ions present in the electrolyte. Regarding X-ray diffraction patterns, the TiO2 phases formed in the Ti-25Ta alloy has a mixture of anatase and rutile, making the MAO surface hydrophilic. The Ag element surface is thicker than the films containing Cu and Zn, as the Ag ions have high electrical conductivity, accelerating the oxidation process during surface treatment. Regarding hardness, coating containing Cu have a higher hardness value.

Nickel alloys and composites are interesting engineering materials as a result of a combination of mechanical, corrosion and wear resistance at service temperatures that exceed those of steels and steel-based materials. The present study aimed at sintering Ni-graphite composites from NiO-SiC mixtures and investigate the in-situ formation of graphite. NiO powders were mixed with SiC (0, 3, 5 and 10 wt.%) and attrition-milled during 1 h. The mixtures were then granulated using 1.5 wt.% paraffin in hexane solution and uniaxially pressed under 400 MPa. The cylindrical pellets were then sintered at 1200 ºC. The sintered materials were characterized by density measurements, dilatometric and microstructural analyses, as well as Vickers microhardness. The results showed that Ni-graphite composites were successfully produced from NiO-SiC mixtures with full reduction of NiO and dissociation of SiC to form a Ni-Si matrix and graphite nodules.

Since graphene and its derivatives discovery, the desire to develop accessible production methods and obtain high-quality materials to enable its production on an industrial scale has increased research interest in this field, and in techniques aiming a deep characterization of these materials. Based on this, the present study proposes a great reduction of time in the process steps of reduced graphene oxide (rGO) production. By using micronized graphite as the precursor, the exfoliation and reduction time were reduced, 67 and 75% respectively, without compromising rGO properties. Regarding the number of layers, the carbon structures presented results between 7 (rGO) and 10 (graphene oxide), being the best result of 8 layers after 10 minutes of exfoliation. Moreover, the electrical conductivity methodology proposed in this article was based on statistical analysis. The electrical conductivity of suspensions with 0.5% w/w of carbon structures was between 3400 and 3700 µS.cm-1. Thus, this study opens the way for obtaining graphene oxides by the modified Hummers’ method and shorter process time in exfoliation and reduction steps using micronized graphite as the precursor, and it also provides a methodology to determine the electrical conductivity of suspensions to assist these materials characterization without prior elimination of the solvent.

This study describes titanium and zirconium incorporations into a FAU zeolite and subsequent modification with nickel hexacyanoferrate.The obtained materials (ZTiNiH and ZZrNiH) were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Dispersive Energy Spectroscopy (EDS), Porosity and Surface Area and Cyclic Voltammetry (CV). The cyclic voltammograms of the modified ZTiNiH and ZZrNiH carbon paste electrodes in the proportions graphite-modifier (20% m/m) indicate sensitivity to isoniazid (IZN). The modified ZTiNiH carbon paste electrode displayed a linear analytical curve response from 4.0× 10–5 to 7.0× 10–4 mol L−1 and a limit of detection of 4.9×10-5 mol L-1, while the modified ZZrNiH electrode presented a linear analytical curve response from 1.0×10-5 a 3.0×10-4 mol L-1 and a limit of detection of 2.0×10-5 mol L-1. The amperometric sensitivity was 47.59 mA/mol L-1 and 20.55 mA/mol L-1 for ZTiNiH and ZZrNiH respectively. After catalytic IZN electro-oxidation, a study concerning the main IZN interferents was performed and its recovery from a synthetic urine sample was assessed. The obtained ZTiNiH and ZZrNiH materials are noteworthy for their good limit of detection and recovery eficiency when applied to real samples, thus comprising potential candidates for the development of electrochemical sensors aiming at IZN detection.

In this work, the surfactant cetyltrimethylammonium bromide (CTAB) was applied to observe how increasing the surfactant's concentration will affect the MgO characteristics, such as the increase in vacancies. The samples were characterized by X-ray diffraction (XRD). For the MgO-0.025CTAB sample, the intensity of the (200) peak of MgO decreased by three. However, the MgO-2.5CTAB showed an increase in the peaks intensity. In addition to using Rietveld refinement, it is possible to observe the textural characteristics of the samples, with the introduction of CTAB, oxygen vacancies increased, and from the MgO to the MgO-0.025CTAB sample, there was a decrease in oxygen occupancy from 94% to 82% in the unit cell. Thermogravimetry (TG) analyses were used to understand the interactions between the support and the surfactant as the CTAB concentration increased. With the physisorption of N2, the behavior of the sample pores and specific area determination are verified. The introduction of CTAB caused the decrease of the specific area from 32 m2/g to 9 m2/g for the MgO and MgO-0.025CTAB samples. However, for a more concentrated surfactant, MgO-2.5CTAB, the specific area was 25 m2/g. Scanning electron microscopy made it possible to observe the increase in the roughness with CTAB presence.

In this work, epoxy resin-based composites reinforced with nanoclays, nanoalumina, carbon nanotubes (CNTs) (0.15, 0.50, and 1.50% vol were submitted to morphological characterization by scanning (SEM) and transmission (TEM) electron microscopies, electrical tests through electrical impedance spectroscopy, and electromagnetic analyses (scattering parameters), in the frequency range of 8.2 to 12.4 GHz. SEM images of the CNT composite revealed nanotube clusters in the matrix. The proximity between the CNTs is corroborated by the increase in the electrical conductivity of the composite due to the formation of a long-range electron transport network, which favored the polarization effect, absorption losses (SEA = 1.33 dB), reflection (SER = 3.38 dB) and reflection loss (RL = -6.61 dB at 10.8 GHz). Composites with nanoclays and nanoalumina showed no significant electrical and electromagnetic results.

In the present study, non-thermal plasma (NTP) of dielectric barrier discharge (DBD) was used to investigate the precipitation of salt from hypersaline waters obtained by evaporating seawater. A dripper was used to release drops of water over the NTP discharge between the droplet surface and a copper ring in a glass tub working as a DBD. Results showed that the precipitation rate of the NTP-treated solution was significantly higher than that of the untreated solution, with a larger number of small crystals formed, and multiple charged ions preferentially precipitated. These findings suggest that the external electric field from NTP aligns and weakens the hydration of ions, leading to the binding of dehydrated cations and anions, and inducing nucleation/precipitation. Additionally, the NTP discharge channels formed at the gas-liquid interface cause rapid dehydration of ions, which further induce nucleation and crystal formation. This could explain the preferential precipitation of small crystals containing multiple charged ions. Overall, the results demonstrate that NTP-DBD is a promising approach for efficient precipitation of salts from hypersaline waters.

This study investigated the efficiency of the natural anticorrosive coating of propolis extract (PE) on CA-50 carbon steel in a solution that simulates the liquid phase of the concrete pore condition, called cement extract (CE). Fourier transform infrared (FTIR) and high-performance liquid chromatography (HPLC) analyses of the propolis extract identified inhibitory functional groups, with Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) being the predominant component present in the propolis extract (PE). To examine the inhibition capacity of propolis extract on reinforcement, an aqueous solution of 3.5 wt.% NaCl solution was added to the cement extract in the presence and absence of PE. Electrochemical techniques such as open circuit potential, polarization curves and electrochemical impedance spectroscopy were carried out to study corrosion efficiency. Scanning electron microscopy (SEM) was performed to characterize the sample surface. The results show that PE was effective as an anti-corrosion coating for carbon steel in the environment studied, indicating the formation of a protective film with higher stability.

The corrosion resistance of chromium-plated steel sheets produced on an industrial scale was investigated. Two parameters of the production process were considered: pickling and chemical treatment. The specimens were produced at the industrial plant considering two different pickling conditions and two different chemical treatments: non-electrolytic and electrolytic pickling and non-electrolytic and electrolytic passivation respectively. Accelerated corrosion tests in the humid chamber, microscopy analyses, analyses of roughness and content of trivalent chromium in the passivation film and analyses of the content of metallic chromium in the coating by coulometry technique were performed. The results showed a low corrosion resistance of the materials produced with the non-electrolytic passivation, regardless of the pickling condition. The highest degree of protection of the base steel was achieved for the specimen produced by using the electrolytic route for both pickling and chemical treatment steps. This condition produced a mass of trivalent chromium in the passivation film greater than 8.0 mg∙m-2, which provided an effective performance of the chromium-plated steel sheet.