Search Results (9,931)

Hierarchical ZnO–SiO₂/carbon composites (C-Zn1, C-Zn2, C-Zn3) were synthesised via the carbonisation of resorcinol–formaldehyde gels in the presence of ZnO-modified fumed silica, and characterised by N₂ adsorption–desorption, FTIR, XRD, SEM, and zeta potential analysis. The composites exhibited hierarchical micro–mesoporous structures with BET surface areas of 467–499 m² g⁻¹; the non-microporous volume fraction increased from 0.09 (reference carbon RFC, 545 m² g⁻¹) to 0.54–0.63 upon ZnO–SiO₂ incorporation. Adsorption of methylene blue (MB), crystal violet (CV), and rhodamine 6G (R6G) followed the Marczewski–Jaroniec isotherm model. Maximum adsorption capacities for the best-performing composite (C-Zn1) reached 1.22 mmol g⁻¹ for MB, 1.04 mmol g⁻¹ for CV, and 0.63 mmol g⁻¹ for R6G, compared to 1.32, 1.17, and 0.67 mmol g⁻¹ for unmodified RFC. Kinetic analysis revealed up to 3.5-fold faster adsorption rates for C-Zn1 relative to RFC (for CV and R6G), attributed to enhanced diffusion through mesoporous channels while preserving the micropore-driven capacity. Agar well-diffusion assays against four bacterial strains showed no inhibition zones for any composite, indicating that no biologically active concentration of zinc species was released under the assay conditions. The proposed approach yields composites with enhanced adsorption kinetics, preserved capacity, and confirmed non-leaching character, positioning them as effective candidates for water purification. Full article

Silicon carbide–aluminum (SiC–Al) composites offer high hardness, wear resistance, thermal stability, and strength-to-weight ratio, making them suitable for advanced engineering applications. Fabricating these composites via powder metallurgy and infiltration methods has been reported. However, there is no reported study on fabricating SiC–Al composites using binder jetting additive manufacturing (BJAM) followed by sintering without infiltration. The present study aims to fill this gap. In this study, samples were printed by BJAM using SiC–Al mixed powders with two volumetric ratios (SiC:Al) of 60:40 and 80:20, respectively. These printed samples were then sintered at different temperatures (950 °C, 1200 °C, and 1400 °C). The results show that, using this new approach, the printed green samples retained structural integrity after sintering and that interparticle bonding was achieved. To the authors’ knowledge, this is the first study to fabricate a SiC–Al composite via binder jetting additive manufacturing using a mixed powder, followed by sintering without infiltration. Full article

GeSi alloy quantum dots (QDs) are a promising candidate for a light source implemented in Si-based monolithic optoelectronic integrated circuits (MOEICs) thanks to their telecom-wavelength emission and the compatibility with the Si integration technology. Herein, the engineering properties of GeSi alloy QDs are demonstrated via rapid thermal annealing (RTA). The PL spectra of GeSi alloy QDs exhibits remarkably enhanced intensity and an initial red shift followed by a blue shift with increasing annealing temperature. Particularly, it can be characterized as a single narrow peak at ~1.55 µm of the intensity enhanced by ~20 times after the RTA at 1100 °C. These features are attributed to the progressively enhanced intermixing and the abnormal transition from compressive strain to tensile strain in QDs with increasing annealing temperature, which are demonstrated by Raman spectra and transmission electron microscopy (TEM) images. Moreover, a large polycrystalline-domain appears around QD at a sufficiently high annealing temperature. It facilitates the tensile strain in QDs, which arises during the RTA due to the thermal expansion coefficient mismatch between Ge and Si. These results demonstrate that high-temperature annealing can efficiently modulate the properties of GeSi alloy QDs, particularly for emission at 1.55 µm, which may have great potential for an efficient Si-based light source. Full article

Pyrrolidinyl-substituted silacyclopentane (CH₂)₄Si(Pyr)₂ and α-amino isobutyric acid (H₂Aib) react with the release of one equivalent pyrrolidine (HPyr) and the formation of the pentacoordinate silicon bis-chelate (Aib)Si(CH₂)₄(HPyr), which features the di-anion of the amino acid as an (O,N)-chelator and one equivalent of pyrrolidine as an additional lone-pair donor. Crystallographic analyses of the chloroform solvate (Aib)Si(CH₂)₄(HPyr)·(CHCl₃), which undergoes a phase transition at 200 K, and a solvent-free modification (Aib)Si(CH₂)₄(HPyr), which features two crystallographically independent molecules of the complex, revealed that the N atom of the HPyr ligand, as well as the carboxylate of Aib, occupy the axial positions in the trigonal bipyramidal Si coordination sphere; the Si–C bonds of the silacyclopentane rest on equatorial sites. For the isolated molecule in a solvent environment, computational analyses revealed that the energy difference between this configuration and the related isomer with an equatorial HPyr and equatorial–axial positioning of the silacyclopentane motif is marginal. In DMSO solution, the adduct (Aib)Si(CH₂)₄(HPyr) decomposed, forming the hexacoordinate Si complex (HAib)₂Si(CH₂)₄ as one of the decomposition products. In a deliberate manner, this compound was accessible from the diethylamino-substituted silacyclopentane (CH₂)₄Si(NEt₂)₂ and H₂Aib with the liberation of diethylamine. (HAib)₂Si(CH₂)₄ features two mono-anions of the α-amino acid as (O,N)-chelators, their carboxylate O atoms are trans-disposed to silacyclopentane, and their NH₂ groups are mutually trans. Full article

This study investigates the thermochemical reaction behaviour of scheelite–millscale aluminothermy for direct tungsten alloying in steel production. Experimental mixtures of aluminium, millscale, and scheelite concentrate were simulated using gas–slag–metal (g-s-m) equilibrium calculations in FactSage 8.3 at 2200 °C, and compared with previously reported experimental results. The simulations reproduced metal yields accurately with 0.901 to 0.940 correlation coefficients and predicted tungsten levels consistent with measured steel compositions. However, significant discrepancies were observed in predicted silicon levels, with simulations overestimating steel %Si by up to 3.5%, despite negligible gas-phase losses. Oxygen partial pressure calculations indicate that the Fe/FeO reaction equilibrium controls process reduction conditions. Backcalculation of activity coefficients revealed that FactSage minimisation routines understated silicon activity coefficient values. SiO₂ mass transfer may play a role in low %Si in steel, but this is not clear due to differences in expected mass transfer regimes in aluminothermy under ASR and SHS conditions. Overall, the simulations demonstrate adequate predictive capability for alloying trends and metal yields while highlighting limitations in predicting silicon partitioning. These findings confirm the utility of thermochemical simulation for designing aluminothermic feed mixtures, reducing the number of experiments needed to optimise the aluminothermic feed mixture ratios. Full article

The accelerated global transition toward eco-friendly mobility has necessitated robust decarbonization measures across the maritime sector, with battery-powered electric propulsion ships emerging as a promising alternative. Accordingly, the applicability of silicon carbide (SiC)-based technology to propulsion inverters, a key component of such vessels, is currently under investigation. Although life cycle assessment (LCA) studies comparing conventional silicon (Si)-based and SiC-based inverters have been conducted previously, these analyses neglect realistic operating profiles and load fluctuations, limiting their applicability. Furthermore, life cycle cost assessment (LCCA) integrating real-world operating conditions has rarely been addressed. To address these gaps, this study conducted a comparative LCA and LCCA of Si IGBT and SiC MOSFET inverters for marine electric propulsion systems across three vessel types: a cruise ship, a passenger and car ship, and a recreational boat, incorporating real-world load profiles to evaluate global warming potential (GWP), fossil depletion (FD), and cumulative energy demand (CED). The static LCA results showed negligible differences between inverter types, contributing less than 1% to total impacts. The dynamic LCA demonstrated that SiC MOSFET inverters reduced environmental impacts by approximately 57%, 52%, and 34% for cruise ships, passenger and car ships, and recreational boats, respectively. Despite a 40% higher initial investment cost, SiC inverters achieved payback periods well within vessel lifetimes across all vessel types. These findings support SiC inverters as a sustainable and economically viable solution for ship electrification. Full article

Lithium-containing ceramics were significant tritium breeders for the fusion blanket concept, for which tritium release performance and mechanical properties serve as the core indicators for evaluating their performance as tritium breeders. The Li₄Si_0.8Ti_0.2O₄ material was designed as an advanced tritium breeder and fabricated into ceramic pebbles via the freeze-drying method. The tritium release properties of the Li₄Si_0.8Ti_0.2O₄ sample pebbles were investigated via temperature-programmed desorption (TPD). The mechanical properties of the same batch of tritium breeder pebbles were analyzed comparatively, specifically examining the change in their compressive strength before and after irradiation. The sample pebbles irradiated with different neutron doses show different tritium release characteristics, and the tritium release temperature was about 293–553 °C. This was due to the H₂-tritium isotope exchange reaction, and radiation with different neutron doses will lead to different release temperatures of tritium. The mechanical properties of the Li₄Si_0.8Ti_0.2O₄ ceramic pebbles decreased significantly after irradiation. The main reason was that the accumulation of lattice defects and helium bubbles produced by high-energy neutron irradiation leads to internal cracks and helium embrittlement in the material. These results indicate that Li₄Si_0.8Ti_0.2O₄ solid solution may be considered a potential candidate for tritium breeder materials. Full article

Achieving stable local focus-height measurement across different material surfaces is important for I-line-lithography-related inspection, where sub-micrometer height deviations can affect imaging quality, exposure uniformity, and subsequent autofocus performance. This study evaluates the local focus-height repeatability of a linear charge-coupled device (LCCD)-based focus metrology system under several I-line-lithography-related material-surface conditions. The prototype integrates fiber-coupled LED illumination, telecentric projection and imaging optics, reference marks, and a two-step localization procedure based on template matching and centroid estimation; the dual-wavelength source is treated as part of the fixed optical configuration. Tests were performed on silicon wafers, GaAs bright substrates, sapphire, infrared transmissive material, and SiC, covering different reflectivity levels and surface structures. The measured peak-to-valley repeatability was 35–37 nm for highly reflective samples and 40–54 nm for intermediate- or low-reflectivity and microstructured samples, all below the selected 70 nm conservative engineering criterion derived from the depth-of-focus estimate. These results indicate that the integrated LCCD measurement chain maintained stable local repeatability within the tested material-surface range, providing experimental support for further development of local focus metrology and precision optical inspection. Full article

This paper proposes a mathematical co-design framework for synchronous Boost DC-DC converters and their PI voltage controllers. In contrast to the conventional sequential design approach, where the power stage is sized first and the controller is tuned afterward, the proposed method treats the converter and the controller as a single coupled design problem. A nonlinear averaged model of the synchronous boost converter operating in continuous conduction mode is considered, explicitly incorporating the inductor series resistance, the capacitor equivalent series resistance, and the on-state resistances of the active switches. In addition, a simplified but physically interpretable loss model is included in order to capture inductor copper loss, capacitor ESR loss, semiconductor conduction loss, and switching loss. Based on this formulation, the joint design of the power stage and the PI controller is cast as a constrained multi-objective optimization problem whose decision variables include the inductance, capacitance, switching frequency, and controller gains. The optimization criteria account for output-voltage ripple, settling time, total losses, and current stress, while practical constraints related to duty cycle, current limits, ripple bounds, and closed-loop feasibility are enforced. The proposed framework makes it possible to compute Pareto-efficient designs and to reveal trade-offs that remain hidden under classical decoupled design procedures. Numerical case studies are structured to compare the proposed co-design strategy with a conventional sequential-design baseline. An optional technology-aware extension is also considered, allowing the influence of different semiconductor classes, such as Si, SiC, and GaN, to be assessed through technology-dependent loss and switching-frequency assumptions. The results indicate that the proposed framework provides a mathematically grounded and practically useful basis for integrated converter–controller synthesis in nonideal power electronic systems. Full article

This study investigates the oxidation behavior and microstructural evolution of Sanicro 25 steel (X7NiCrWCuCoNb25-23-3-3-2) after long-term exposure to water vapor at 700 °C for 30,000 h. Particular attention was paid to the relationship between protective oxide-scale formation, chromium depletion in the near-surface region, and the possible changes in secondary-phase stability in the steel substrate. FIB-SEM tomography was applied to characterize the oxide scale and the underlying affected zone, enabling three-dimensional visualization of oxide morphology, interfacial voids, and microstructural reconstruction beneath the scale. Long-term exposure resulted in the formation of a continuous Cr-rich oxide scale with a thickness of approximately 2.6 µm and local Mn enrichment. The scale exhibited a complex multilayered morphology, consisting of outer Cr-rich oxide crystallites, fine-grained chromium oxides, and an inner heterogeneous Mn-enriched region, suggesting the possible formation of mixed spinel-type oxides. Si-enriched regions were observed near the oxide/metal interface; however, no continuous Si oxide layer was detected. Despite the presence of interfacial voids, no scale spallation was observed in the investigated regions. SEM-EDX analysis revealed a chromium-depleted subsurface zone extending to approximately 6.5 µm below the oxide scale. CALPHAD calculations suggest that local chromium depletion may reduce the thermodynamic stability of Cr-rich M₂₃C₆ carbides and the Nb–Cr–N-type Z phase. This possible reduction in phase stability may contribute to the formation of a precipitate-depleted region and local microstructural reconstruction beneath the oxide scale. In the bulk region, where oxidation effects were negligible, the microstructure consisted of an austenitic matrix containing M₂₃C₆ carbides, σ phase, Cr–Ni–Fe nitride with an A13-type structure, ε-Cu precipitates, Z phase, and W-rich Cu-containing TCP precipitates. The simulations further suggest that most secondary phases form during the early stage of annealing, whereas prolonged exposure is dominated by diffusion-controlled coarsening. Overall, Sanicro 25 shows good resistance to long-term steam oxidation at 700 °C due to the formation of a continuous Cr-rich protective scale. However, this protection is accompanied by chromium depletion and local near-surface microstructural changes, which should be considered when assessing the long-term stability and service performance of this steel under high-temperature steam conditions. Full article

To address the performance degradation associated with retained high-temperature δ-ferrite in welded joints of high-silicon 20Cr11W2VTaSi steel—a candidate structural material for spallation targets in Accelerator Driven Subcritical Systems—this study systematically investigates the microstructural evolution and mechanical behavior of 20 mm-thick forged joints produced via automated tungsten inert gas (TIG) welding using a 7° U-groove narrow-gap configuration. Results demonstrate that the narrow-gap process—featuring reduced filler metal deposition and low heat input—is believed to suppress macrosegregation of ferrite-stabilizing elements (e.g., Cr, Si, Mo). As a result, the δ-ferrite content in the weld metal is constrained, exhibiting a fine, dispersed, worm-like morphology embedded within a uniform matrix of tempered martensite. Microhardness mapping confirms homogeneous hardness distribution across the joint, closely matching that of the base metal, with no statistically significant localized softening zones identified. Mechanical characterization reveals an optimal balance of strength and toughness: the joint achieves a room-temperature tensile strength of 820 MPa and retains 436 MPa at 550 °C; moreover, the Charpy impact energy at the weld center reaches 171.2 J. Full article

Worn roller mill roll shafts made of Steel 45 require cost-effective surface restoration; plasma transferred arc (PTA) deposition of Ni–Cr–B–Si + WC composite coatings is a promising approach, yet the effect of arc current on coating quality remains insufficiently characterised for this substrate. Six coatings were deposited from PS-12NVK-01 powder (65 wt.% PG-10N-01 + 35 wt.% WC) at arc currents of 50–100 A on Steel 45 substrates using a ZTW3501DC PTA system; coatings were characterised by SEM, EDS mapping, XRD (HighScore Plus, PDF-2), Vickers microhardness profiling, and ball-on-flat tribological testing. EDS analysis revealed that compositional dilution increases from 18.1% at 60 A to 46.6% at 100 A; XRD identified WC + Cr₃C₂ + Ni₃B + Ni₂B + (Fe,Ni)γ at 50 A, transitioning through Cr₇C₃ + W₂C dominance at 80 A to an Fe₀.₆₄Ni₀.₃₆ matrix at 100 A; and coating thickness peaked at 2.70 mm at 80 A. The 60 A coating yielded the highest surface hardness (887 ± 76 HV, >4× the substrate), the lowest specific wear rate (4.00 × 10⁻⁶ mm³/(N·m), ~22× lower than uncoated Steel 45), and minimum dilution (18.1%), identifying 60 A as the most favourable deposition current for the restoration of roller mill roll shafts under the process parameters employed. Full article

In this work, to address the limitation of low strength and hardness of single-phase CoCrFeNi high-entropy alloy, SiC particles were introduced as a reinforcing phase to prepare CoCrFeNi matrix composites with SiC contents of 0 wt%, 1 wt%, 2.5 wt% and 5 wt% via spark plasma sintering (SPS). It was preliminarily predicted that SiC particles would be uniformly distributed along grain boundaries of the CoCrFeNi matrix. During sintering, partial SiC decomposes at high-temperature, high-activity interfaces, regulating carbide precipitation and phase structural evolution, while residual undecomposed SiC remains at grain boundaries to pin boundaries and refine grains, thereby synergistically enhancing mechanical properties and wear resistance. Microstructural characterization reveals that all samples maintain a face-centered cubic (FCC) solid-solution matrix, and samples with non-zero SiC addition contain Cr₇C₃ carbides, which are mostly distributed at grain boundaries. With the increase in SiC content, mechanical performance is remarkably improved compared with the unreinforced CoCrFeNi matrix: the hardness rises from 198.8 HV to 321.7 HV, the yield strength is greatly enhanced from 242.5 MPa to 673.4 MPa, and the tensile strength increases from 557.9 MPa to 755.7 MPa. The improved yield strength originates synergistically from grain refinement, solid-solution strengthening, grain-boundary strengthening and dislocation strengthening. By clarifying the influence of microstructural defects on critical shear stress (τ₀) and normal fracture stress (σ₀), the intrinsic mechanism governing tensile mechanical performance and ductile–brittle fracture transition was revealed. This optimized CoCrFeNi/SiC composite exhibits excellent strength–hardness comprehensive performance, showing promising application potential for high-load, wear-resistant and structural service components under severe tribological and pressure conditions. Full article

The present study addresses the fabrication of porous gyroid architectures by additive manufacturing from preceramic polymer feedstocks. Photocurable emulsions were engineered by combining a silicone powder with acrylate monomers and dispersing an emulsified secondary phase of calcium nitrate. The formulations showed light-curing behaviour compatible with digital light processing vat photopolymerization (DLP-VPP), enabling high-fidelity replication of triply periodic minimal surface (TPMS) gyroids (designed porosity: 85 vol.%). After pyrolysis in nitrogen at 700 °C, the lattices converted into CaO–SiO₂-derived amorphous matrices embedding an in situ turbostratic/pyrolytic carbon fraction, as suggested by the photothermal response and preliminary impedance behaviour, although the latter was measured in liquid electrolyte and therefore does not isolate electronic transport. To improve robustness during polymer-to-ceramic conversion, pharmaceutical borosilicate waste glass (BASG) was added as a passive filler (30–70 wt.%). The waste-glass phase acts as a passive filler that improves processing robustness and can mitigate shrinkage-induced damage during pyrolysis, while remaining electrically insulating (dielectric) and therefore not directly contributing to electronic conduction. The resulting structures combine high surface-to-volume ratio, controlled open porosity, and structural integrity with electrochemical responsiveness under the adopted test conditions, making them promising architected platforms for electrochemical components where interconnected porosity is advantageous. Full article

High-nickel NCA/Si–C 21700 cells exhibit strongly condition-dependent degradation, but the coupled influence of temperature and rate on electrochemical, thermal, and structural evolution remains insufficiently resolved. Here, Samsung INR21700-50E cells were aged under a 3 × 3 matrix of ambient temperatures (0, 23, and 40 °C) and C-rates (0.5C, 1C, and 2C). Periodic reference performance tests were used to track capacity, 10 s direct-current internal resistance, electrochemical impedance, pseudo-open-circuit voltage, differential voltage/incremental capacity behavior, heat generation, and post-mortem morphology. Guided by the hypothesis that temperature and rate history change not only the speed but also the dominant pathway of aging, the results show that both ambient temperature and the charge/discharge rate program govern the aging trajectory. Low-temperature cycling accelerates capacity loss and resistance growth through severe polarization and lithium plating, indicating dominant loss of lithium inventory. High-temperature operation promotes interfacial side reactions, impedance rise, and cathode structural degradation, leading to stronger loss of active material at later stages. An increasing C-rate amplifies these effects by raising overpotential and thermal load. Heat generation power increases markedly with aging and depends strongly on temperature–rate history. Scanning electron microscopy confirms cathode cracking, anode surface film thickening, and separator degradation under severe conditions. These experimental indicators are integrated into a mechanism-aware diagnostic framework that maps capacity retention, DCIR/EIS parameters, ICA/DVA indices, and heat generation metrics to dominant aging modes, supporting BMS state-of-health estimation, lifetime prediction, thermal management, and second-life screening of high-nickel NCA cells. The condition-averaged trajectories are further converted into a semi-empirical aging law that links capacity loss, resistance growth, and heat generation increase for BMS-oriented lifetime prediction. Full article