Search Results (1,061)

The quantitative evaluation of permeability resistance remains a major challenge in the assessment of IL corrosion inhibitors. Here, we presented a morphology-based methodology that combined electrochemical impedance spectroscopy for inhibition coverage with confocal microscopy three-dimensional analysis to quantify surface roughness (S_a), thereby establishing a dual-criterion framework. At high inhibition efficiency (>73%), surface roughness ranking at identical concentrations directly reflected permeability resistance, whereas under insufficient efficiency, concentration-gradient experiments effectively eliminated coverage interference. Application to three chemically different imidazolium-based ILs ([C₃mim][OTf], [C₃mim][NO₃], and [C₃mim][Br]), which were studied at three different concentrations (10, 30, and 50 mM), revealed a nonlinear relationship between inhibition efficiency and surface roughness, with the nitrate system exhibiting the most favorable permeability resistance. This strategy provided a critical dimension for the quantitative evaluation of IL corrosion inhibitors and advanced the understanding of their protective mechanisms. Full article

Additive manufacturing (AM) enables the fabrication of complex geometries and high-performance alloys such as 17-4PH stainless steel. However, the surface defects inherent to AM components compromise corrosion resistance. The post surface treatment can reduce and eliminate these defects. This study examines the effect of centrifugal mass finishing on the corrosion behaviour of 17-4PH stainless steel produced by AM. Corrosion behaviour of the samples in a 0.6 M NaCl solution is assessed using electrochemical technique testing, including asymmetry electrochemical nose, potentiodynamic polarisation curves, electrochemical impedance spectroscopy, and Mott-Schottky. All electrochemical testing were conducted in concordance with the specifications of ASTM standards. The electrochemical impedance spectroscopy were performed over period ranging from 2 h to 96 h with intervals of approximately one day. Finished specimens exhibit significantly improved corrosion resistance compared with as-built counterparts. Notably, the polished surfaces demonstrate spontaneous oxidised layer recovery between −0.297 V and 0 V, indicative of the enhancement of the protection during early immersion stages. This behaviour is attributed to surface modifications induced by the finishing process, including reduced roughness in 78% and imperfections. These findings highlight the importance of optimising post-processing protocols to improve the durability of AM stainless steels in aggressive environments. Full article

The long-term corrosion protection of copper surfaces modified with self-assembled hydrophobic layers (SAHLs) based on stearic acid (SA) and two fat-soluble vitamins, vitamin K₃ (menadione) and vitamin E (E307), was investigated in simulated acidic urban rain (pH 5) over 7 days. The SAHLs were characterised by SEM, contact angle goniometry, ATR-FTIR, potentiodynamic polarisation, and electrochemical impedance spectroscopy (EIS). Surface modification was achieved by immersing copper samples in ethanolic SA solutions containing 2.0 wt% of fat-soluble vitamins. Variants included individual additives, (SA + 2.0 wt% K₃) and (SA + 2.0 wt% E307), as well as mixtures with a constant total additive content of 2.0 wt%: (SA + [1.5 wt% K₃ + 0.5 wt% E307]) and (SA + [1.0 wt% K₃ + 1.0 wt% E307]). The (SA + 2.0 wt% K₃) modification produced needle-like microstructures with strong short-term inhibition but poor long-term stability, while (SA + 2.0 wt% E307) formed smoother, more stable films. The mixture containing equal mass fractions of vitamins, (SA + [1.0 wt% K₃ + 1.0 wt% E307]), exhibited a synergistic effect, yielding hierarchically structured, flower-like morphologies with high polarisation resistance and stable impedance over 7 days. These results show that combining K₃ and E307 with stearic acid provides robust, environmentally friendly, and durable protection for copper surfaces. Full article

In this paper, a 3D-printed S-Band corrugated horn antenna with X-Band radar cross section (RCS) reduction is investigated. This work demonstrates effective RCS reduction at the X-band through the application of the phase cancellation principle. Specifically, the corrugated horn antenna is partitioned into eight identical sections, with three discrete height offsets introduced between them. The reflection phase cancellation, which can be attained through the path difference introduced by a designed height step among different regions, leads directly to a consequent suppression of scattered waves. The proposed low-RCS corrugated horn antenna is monolithically fabricated using stereolithography appearance (SLA) 3D printing technology, followed by a surface metallization process. The measured results demonstrate that the proposed antenna operates over the frequency band of 2.34–3.3 GHz in the S-band with good impedance matching, exhibiting a peak gain of 11.7 dB. Furthermore, the monostatic RCS of the antenna under normal incidence for both x- and y-polarizations exhibits a significant reduction of over 10 dB within the frequency range of 8.7–12.0 GHz and 8.2–12.0 GHz, respectively. This indicates that effective stealth performance is achieved across the majority of the X-band. The proposed design integrates exceptional out-of-band RCS reduction, low cost, light weight, and high efficiency, making it a promising candidate for radar stealth system applications. Full article

This study investigates the influence of current density distribution on the hardening behavior of 20GL cast steel during electrolytic plasma processing (EPP). Experimental and numerical methods were combined to establish the relationship between discharge dynamics, heat flux, microstructural transformation. Electrolytic plasma hardening was carried out at cathodic voltages of 150 V and 250 V in a 20% Na₂CO₃ solution. The transient evolution of current density was analyzed using a 3D COMSOL Multiphysics model incorporating a vapor–gas shell (VGS) represented as a distributed impedance layer with realistic conductivity and permittivity. High-speed video confirmed that microdischarges preferentially initiate at sample corners, where modeling also predicts local current concentration and heat flux up to 12 MW/m². Experimental current density values (3–4 × 10⁴ A/m²) showed good agreement with the simulations. Microhardness tests revealed that increasing voltage from 150 V to 250 V increases the thickness of the hardened layer (from ~250 µm to ~600 µm) and raises surface hardness (up to 750 HV), while polarization tests showed a 40% reduction in corrosion rate. The results highlight that current density distribution governs the non-uniformity of thermal effects and surface strengthening during EPP, emphasizing the importance of electrode alignment and VGS stability for uniform hardening. Full article

This paper presents a dual-polarized millimeter-wave filtering antenna based on a broadband partially reflective surface lens for gain improvement. It consists of a magneto-electric dipole (M-E dipole) as the source and a partially reflective surface (PRS) as the lens. The M-E dipole source antenna employs a dual-layer substrate structure, and its working principle is investigated by the circuit analysis method. A stub-loaded transmission line network is used to study the radiation characteristics of the source antenna, and the simulation results reveal that it has intrinsic integrated bandpass-type filtering response. The PRS lens is realized by designing a square high permittivity superstrate. By combining the source antenna and the lens, a wideband dual-polarized high gain cavity antenna is developed. The fabricated prototype has a measured impedance bandwidth of 33.3% (25–35 GHz), and a maximum in-band gain of 12.3 dBi. Above features make the proposed antenna a good candidate for 5G millimeter-wave sensor applications. Full article

Cellulose nanofibrils (CNFs) provide a green scaffold for next-generation flexible sensors. They unite abundance, mechanical robustness, biocompatibility, and an easily engineered surface. This review synthesizes advances from the past five years in low-carbon CNF manufacturing. We cover biomass pretreatment, high-solid mechanical fibrillation, and in situ functionalization. We then elucidate mechanisms that govern CNF films, aerogels, and double-network hydrogels used across humidity, temperature, strain/pressure, optical, electrochemical, and biosensing platforms. Particular attention is given to multiscale conductive networks, surface-charge regulation, and reversible dynamic crosslinking. Together, these motifs raise sensitivity, widen the linear response windows, and strengthen environmental tolerance. We interrogate bottlenecks that impede scale-up, including energy demand, batch-to-batch variability, and device-level integration. We also assess prospects for deep-eutectic-solvent recycling, roll-to-roll digital printing, and algorithm-guided structural design. Finally, we outline directions for self-healing and self-powered biomimetic architectures, fully degradable life-cycle design, and integrated “sense–store–compute” nodes. These analyses chart a credible path from laboratory discovery to industrial deployment of CNF-based sensing technologies. Full article

This study addresses the technical challenges of cracking and surface crack initiation in Ni60 alloy cladding layers fabricated by laser cladding additive manufacturing on FeMnNiSi alloys. An innovative FeMnNiSi-Inconel625-Ni60 laminate design was proposed, achieving metallurgical bonding of the dissimilar materials through an Inconel625 transition layer. This effectively addresses the interfacial stress concentration issue caused by differences in thermal expansion coefficients in conventional processes. The results demonstrate that the interfacial microstructure is regulated by synergistic Nb-Mo element segregation, promoting the precipitation of γ″ phase and the formation of a nanoscale Laves phase. This phase not only inhibits carbide aggregation and growth, refining grain size, but also deflects crack propagation paths by pinning dislocations, achieving a dual mechanism of stress reduction and crack arrest. The Ni60 cladding layer in the laminated structure exhibits an average surface microhardness of 641.31 HV_0.3, 3.88 times that of the substrate (165.22 HV_0.3), while the Inconel625 base layer shows 340.71 HV_0.3, 2.06 times the substrate’s value. Wear testing reveals the laminated cladding layer has a wear volume of 0.086 mm³ (0.243 mm³ less than the substrate’s 0.329 mm³) and a wear rate of 0.86 × 10⁻² mm³/(N·m), 73.86% lower than the substrate’s 3.29 × 10⁻² mm³/(N·m), indicating superior wear resistance. The electrochemical test results show that under the same corrosion conditions, the self-corrosion potential and polarization resistance of the FeMnNiSi-Inconel625-Ni60 cladding layer are significantly higher than those of the substrate, while the corrosion current density is significantly lower than that of the substrate. The frequency stability region at the highest impedance modulus |Z| is wider than that of the substrate, and the corrosion rate is 71.86% slower than that of the substrate, demonstrating excellent wear resistance. This study not only reveals the mechanism by which Laves phases improve interfacial properties through microstructural regulation but also provides a scalable interface design strategy for heterogeneous material additive manufacturing, which has important engineering value in promoting the application of laser cladding technology in the field of high-end equipment repair. Full article

There is a knowledge gap about the effect of pharmaceutical agents on the biodegradation of Mg-based resorbable implants. The present work investigates how three common antibiotics and three anti-inflammatory drugs affect the corrosion of high-purity Mg, with and without ceramic and hybrid ceramic/polymeric coatings, using electrochemical impedance spectroscopy and hydrogen evolution tests. A Ca-P-Si-based ceramic coating is developed using plasma electrolytic oxidation (PEO), after the AC voltage and frequency parameters are optimized. A hybrid coating included a PEO and a poly(ε-caprolactone) (PCL) top layer formed by dip coating. High-purity Mg exhibited an instantaneous onset of corrosion with a corrosion rate of 90 μm/year after 24 h of immersion in a modified α-MEM. A hybrid PEO/PCL coating prevents the onset of corrosion for at least 5 h and reduces the H₂ evolution during the following 90 h by two times by the precipitation of 5–40 μm thick Ca-P surface deposits. Gentamicin, naproxen, streptomycin, ciprofloxacin and paracetamol were found to be corrosion accelerators with respect to bare h.p. Mg, whereas aspirin was found to be an inhibitor. Streptomycin-functionalized PEO/PCL system exhibited an active protection mechanism, triggered upon the release of the coating and substrate cations, associated with the coating defect-blocking action of the insoluble Me(II)-streptomycin chelates. Full article

The oxygen reduction reaction (ORR) is a crucial process in electrochemical systems, such as fuel cells, as it effectively converts oxygen into water, thereby contributing significantly to sustainable energy generation. In this study, copper oxide (CuO) thin films were deposited onto silver (Ag) substrates using a modified successive ionic layer adsorption and reaction (SILAR) method, followed by an investigation of their electrocatalytic performance toward ORR in an alkaline medium. Comprehensive electrochemical characterizations, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and open circuit potential (OCP), were employed to evaluate catalyst behaviour. Elemental analysis through energy-dispersive X-ray spectroscopy (EDX) confirmed the uniform distribution of CuO, while scanning electron microscopy (SEM) revealed a sponge-like surface morphology which potentially enhances catalytic efficiency. Moreover, EIS spectra revealed a lower charge transfer resistance for the CuO/Ag electrode (3.37 kΩ) compared to bare Ag (4.23 kΩ), reflecting improved ORR kinetics. Among different deposition cycles, 15 SILAR cycles yielded the highest current density of 0.8 mA cm⁻² at 0.60 V. Kinetic analysis revealed that the reaction is irreversible, with a lower value of Tafel slope (32 mV dec⁻¹) and high transfer coefficient (α = 0.45), indicating a concerted reduction mechanism. The ORR pathway was found to follow a four-electron (4e⁻) transfer process. Full article

This study presents a comprehensive characterization of a commercial water-based epoxy primer applied to galvanized steel sheets, which are commonly used in building and construction applications. The investigation focused on evaluating the primer’s adhesion, mechanical strength, chemical resistance, and corrosion protection under various environmental and thermal conditions. Particular attention was given to the effect of substrate sanding prior to application, which was found to influence the coating thickness and surface adaptation. The results demonstrated that the primer provides effective barrier properties and good adhesion to the metal surface, with average pull-off strengths remaining consistent across aged and unaged samples. Electrochemical impedance spectroscopy (EIS) confirmed high polarization resistance values, indicating strong corrosion protection, while SEM-EDS analysis revealed the presence of zinc phosphate and titanium dioxide fillers contributing to both passive and active inhibition mechanisms. However, the primer exhibited sensitivity to ultraviolet (UV) radiation, as evidenced by FT-IR spectra showing increased absorbance in the hydroxyl and carbonyl regions after prolonged exposure. A preliminary estimation of the photodegradation rate, based on FT-IR data at the carbonyl peak (1739 cm⁻¹), yielded a value of approximately 2 × 10⁻⁶ absorbance units per hour between 3000 h and 5000 h of UV exposure. This value suggests a gradual degradation process, although further quantitative validation is required. Additional limitations were observed, including variability in coating thickness due to manual application and localized blistering at cut edges under salt spray conditions. These findings contribute to a deeper understanding of the primer’s behavior and suggest improvements for its practical use, such as the application of a protective topcoat and optimization of the coating process. Full article

Titanium dioxide is attractive for energy storage due to its abundance, stability, non-toxicity, low cost, and favorable electronic/optical properties. Colossal permittivity (CP) in co-doped TiO₂ is mainly linked to defect structures rather than intrinsic bulk behavior. This work studies the dielectric properties of TiO₂ co-doped with niobium and magnesium, synthesized by solid-state reaction. Grain size effects were examined by varying ball milling parameters of (½Mg½Nb)_0.05Ti_0.95O₂ and then were correlated with structure, morphology, and dielectric response. X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and impedance spectroscopy (IS) (40 Hz–10⁶ Hz, 150–370 K) were employed for structural, morphological, and electrical characterization. XRD confirmed the rutile phase. For co-doped samples, larger grains yielded higher dielectric constants, reaching high permittivity (ε′ = 429, T = 300 K, f = 10 kHz at 500 rpm for 2 h). Lower loss tangent (tan δ = 0.11, T = 300 K, f = 10 kHz at 200 rpm for 2 h) is linked to Mg segregation at grain boundaries. The most conductive sample showed the highest dielectric constant, suggesting an IBLC polarization mechanism driven by grain boundary effects. XPS confirmed Nb and Mg incorporation, with Ti⁴⁺ dominant and minor Ti³⁺ from oxygen vacancies and surface hydroxylation/defects. Full article

Metal additive manufacturing (MAM), also referred to as 3D printing, has proven remarkable in the fabrication of complex metal components in multiple sectors. However, the assessment of this revolutionary process through bending fatigue is frequently impeded due to concerns about mechanical and physical conditions of the printed components. The unique layer-by-layer production process results in varied microstructures, anisotropy, and intrinsic defects that considerably differ from traditionally manufactured wrought metals. This review article aims to integrate and evaluate historical and contemporary research on the bending fatigue of additively manufactured materials. More specifically, the impact of process parameters, build orientation, surface conditions, and post-processing techniques such as machining, surface treatments, and polishing on bending fatigue performance are summarized. Adopting prediction methodologies is emphasized to facilitate flaw detection and thereby ensuring the safe and reliable deployment of AM parts in dynamic load carrying applications. Some future research directions are proposed, including the (i) the development of standardized specimens and test protocols, (ii) the adaptation to miniaturization to overcome challenges in high throughput fatigue testing, (iii) the application of emerging geometries such as the Krouse specimen for mechanistic investigations, and (iv) the possibility of developing a correlation across different testing methods and materials to reduce experimental burden. By synthesizing the recent progresses and identifying unresolved challenges, this review outlines an organized and clear pathway towards future research for the deployment of advanced bending fatigue characterization in AM process. The novel idea of adapting miniaturized Krouse geometries in the bending fatigue testing of additively manufactured metals is a viable prospect for the feasible fabrication of AM fatigue coupons with reduced specimen preparation defects and enhanced fatigue strength. Full article

Advancements in flexible, low-cost, and recyclable alternatives to transparent conductive oxides (TCOs) are critical challenges in the sustainability of third-generation solar cells. This work introduces a copper mesh-based transparent electrode for dye-sensitized solar cells, replacing conventional fluorine doped-tin oxide (FTO)-coated glass to simultaneously reduce spectral reflection losses, enhance mechanical flexibility, and enable material recyclability. Titanium dioxide (TiO₂) photoanodes were synthesized and directly deposited onto the mesh via a single-step, low-energy ball milling process, which eliminates TiO₂ paste preparation and high-temperature annealing while reducing fabrication time from over three hours to 30 min. Structural and surface analyses confirmed the deposition of high-purity anatase-phase TiO₂ with strong adhesion to the mesh branches, enabling improved dye loading and electron injection pathways. Optical studies revealed higher visible light absorption for the copper mesh compared to FTO in the visible range, further enhanced upon TiO₂ and Ru-based dye deposition. Electrochemical measurements showed that TiO₂/Cu mesh electrodes exhibited significantly higher photocurrent densities and faster photo response rates than bare Cu mesh, with dye-sensitized Cu mesh achieving the lowest charge transfer resistance in impedance analysis. Techno–economic and sustainability assessments revealed a decrease of 7.8% in cost and 82% in CO₂ emissions associated with the fabrication of electrodes as compared to conventional TCO electrodes. The synergy between high conductivity, transparency, mechanical durability, and a scalable, recyclable fabrication route positions this architecture as a strong candidate for next-generation dye-sensitized solar modules that are both flexible and sustainable. Full article

The industrial production of high-speed steel via continuous casting has been impeded by considerable technical obstacles, due to its high carbon content and fast cooling speed, which predispose it to severe segregation and poor high-temperature plasticity; thus, industrial continuous casting of high-speed steel is virtually nonexistent. In 2022, a curved continuous casting process was successfully applied in the production of M2 high-speed steel; in our previous study, it was found that the carbides were finer and better distributed in the billets by curved continuous casting than those in the billets by ingot casting. The change in carbides in the billets is significant in subsequent processes for M2 high-speed steel produced by curved continuous casting. Therefore, it is necessary to investigate the high-temperature tensile properties of M2 high-speed steel produced by curved continuous casting. In this paper, high-temperature tensile tests were conducted using a GLEEBLE-3500 simulator (DSI, located in New York State, USA) at different temperatures and holding times with a certain strain rate to obtain the tensile strength and reduction of area, and then the morphology of carbides near the fracture surface was observed. The results showed that the tensile strength and reduction of area increased with the increase in temperature at 850 °C to 950 °C, and there existed a temperature range between 950 °C and 1120 °C with good thermoplasticity and a reduction of area from 45% to 50%. In addition, a sharp drop in thermoplasticity below 5% occurred at 1180 °C, which is due to the significant growth of carbides. The zero-strength temperature and plastic temperature were 1220 °C and 1200 °C, respectively. In addition, with the increase in holding time at 1150 °C, the reduction of area increased from 34% to 54%, and the tensile strength decreased from 92 MPa to 70 MPa and then increased to 82 MPa. The best solution for carbides in M2 high-speed steel produced by curved continuous casting occurred when the range of the P_HJ value was about 28.0 to 30.5. With the increase in P_HJ value, the shape of carbides gradually changed from fibrous to short rod-like and blocky during high-temperature diffusion. Full article