Search Results (13)

Sodium (Na) metal anodes suffer from poor processability, severe volume fluctuation, unstable interfacial chemistry, and uncontrolled dendrite growth during cycling, which significantly hinder their practical application. Herein, a Na/Na₂In composite foil is fabricated through an in situ spontaneous alloying reaction enabled by a simple rolling–folding process using Na and indium (In) foils as precursors. Structural characterizations confirm the complete conversion of metallic In into the Na₂In alloy phase, forming a continuous architecture with uniformly distributed Na₂In networks embedded within the Na matrix. Owing to the sodiophilic and mechanically robust Na₂In framework, the Na/Na₂In composite anode effectively regulates Na plating/stripping behavior and suppresses dendritic growth, thereby maintaining a dense and stable electrode morphology during repeated charge/discharge processes. As a result, the Na/Na₂In symmetric cell exhibits stable cycling for over 900 h at 0.5 mA cm⁻² and 1 mAh cm⁻² with low polarization hysteresis, whereas the pure Na counterpart fails after only 143 h. Moreover, full cells paired with NaFe_1/3Ni_1/3Mn_1/3O₂ cathodes deliver enhanced cycling stability, retaining 87% of the initial capacity after 100 cycles at 0.5 C, together with improved rate capability. This work demonstrates a scalable mechanical fabrication strategy for high-stability Na metal composite anodes and provides new insights into the practical development of high-energy-density Na metal batteries. Full article

FLASH radiotherapy requires real-time, non-invasive beam monitoring systems capable of operating under ultra-high dose rate (UHDR) conditions without perturbing the therapeutic beam. In this work, we characterized the extraction system of Supersonic Gas Curtain-based Ionization Profile Monitor (SGC-IPM) for its capabilities as a transverse beam profile and position monitor for FLASH protons. The monitor utilizes a tilted gas curtain intersected by the incident beam, leading to the generation of ions that are extracted through a tailored electrostatic field, and detected using a two stage microchannel plate (MCP) coupled to a phosphor screen and CMOS camera. CST Studio Suite was employed to conduct electrostatic and particle tracking simulations evaluating the ability of the extraction system to measure both beam profile and position. The ion interface, at the interaction region of proton beam and gas curtain, was modeled with realistic proton beam parameters and uniform gas curtain density distributions. The ion trajectory was tracked to evaluate the performance across multiple beam sizes. The simulations suggest that the extraction system can reconstruct transverse beam profiles for different proton beam sizes. Simulations also supported the system’s capability as a beam position monitor within the boundary defined by the beam size, the dimensions of the extraction system, and the height of the gas curtain. Some simulation results were benchmarked against experimental data of 28 MeV proton beam with 70 nA average beam current. This study will further help to optimize the design of the extraction system to facilitate the integration of SGC-IPM in medical accelerators. Full article

To prepare a high-performance Fe-based laser cladding coating, herein, various Fe60/WC/Y₂O₃ coatings are deposited on the surface of 42CrMo steel plate via a laser cladding technique. The WC dosage is fixed as 10 wt%, while the dosage of Y₂O₃ ranges from 0 to 7.5 wt%. The influences of Y₂O₃ dosage on the coating hardness, wear resistance, and corrosion resistance are investigated. With the addition of Y₂O₃, the feature peak of WC disappears, and the peaks of M₂₃C₆ gradually weaken, indicating that Y₂O₃ promotes the decomposition of WC and suppresses the formation of new metal carbides. When the dosage of Y₂O₃ is 2.5 wt%, a grid-like structure is formed on the coating surface, suggesting uniform distribution of decomposed W within the Fe matrix. When the Y₂O₃ dosage exceeds 5 wt%, a large amount of CO₂ gas is released, leading to an increase in surface pores. Through a comparison, the optimal dosage of Y₂O₃ is 2.5 wt%, and the resulting 3# coating has the highest hardness of 861.97 HV. Moreover, the 3# coating also shows the minimum friction coefficient and the minimum wear volume, reflecting its superior wear resistance. The polished coating serves as a working electrode, and the corrosion resistance is tested in 3.5% NaCl solution. The sample containing 2.5 wt% Y₂O₃ has the highest corrosion potential and the lowest corrosion current density, indicating excellent corrosion resistance. The enhanced performance is ascribed to the improved surface quality and the formation of a W-reinforced grid structure. The high-performance coating has promising application potential in material and component repair. Full article

The pore solution in expansive soil contains numerous chemical components that can significantly affect the soil’s water-retention properties, strength, and deformation. This study focuses on Ningming expansive soil and investigates the effects of varying concentrations of NaCl solutions on its water-retention characteristics. The soil–water characteristic curve of expansive soil over the full suction range was obtained using the pressure plate method. The microstructure of expansive soil was analyzed using mercury intrusion porosimetry and scanning electron microscopy. The results indicate that the water-retention capacity of expansive soil increases with higher concentrations of NaCl at equivalent suction levels. MIP tests demonstrated that, regardless of changes in pore solution concentration, the interparticle pores in pre-consolidated samples consistently dominate the pore structure, while agglomeration pores play a secondary role. Importantly, variations in the pore solution concentration primarily alter the characteristics of interparticle pores without significantly affecting their overall structure. SEM analysis revealed that the microstructure of pre-consolidated samples exposed to different pore solution concentrations exhibited less development than that of compactable samples, with a notable reduction in macropores. Furthermore, the arrangement of soil particles became increasingly uniform, and the stratification within the soil matrix was more pronounced. In addition, the Brooks–Corey (BC) model and van Genuchten (VG) model were employed to fit the measured data. It was found that the air entry values predicted by the two models were closely aligned with the measured data; therefore, it is recommended to utilize the average value as the air entry value corresponding to the changes in pore solution concentration of pre-consolidated Ningming expansive soil. Full article

The effects of process parameters on the electroless plating of ionic polymer–metal composites (IPMCs) were studied in this work. Specifically, the NaBH₄ reduction of platinum onto Nafion-117 was characterised. The effects of the concurrent variation of NaBH₄ concentration, stir time and temperature on surface resistance were studied through a full factorial design. The three-factor three-level factorial design resulted in 27 runs. Surface resistance was measured using a four-point probe. A regression model with an R² value of 97.45% was obtained. Surface resistance was found to decrease with increasing stir time (20 to 60 min) and temperature (20 to 60 °C). These responses were attributed to increased platinisation rates, resulting in more uniform electrode deposition, confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Surface resistance decreased, going from 1% to 5% NaBH₄ concentration, but increased from 5% to 10% concentration. This behaviour was attributed to surface morphology: increased grain size inducing porous electrodes, in line with findings in the literature. The maximum tip displacement, measured through a computer vision system, as well as the maximum blocking force, measured through an analytical balance setup, were obtained for all 27 samples. The varying results were discussed with regards to surface and cross-sectional SEMs, alongside EDAX analysis. Full article

The escalating demand for heating and the widespread use of CO₂-emitting fossil fuels during cold seasons have imposed significant pressure on our natural resources. As a promising alternative to coal-fired boilers, electrical thermal storage devices (ETSDs) for space heating are gaining popularity. However, designing ETSDs for space heating involves significant challenges, which involve their storage rate and operational stability. In contrast to the research of directly developing mid-temperature ETSDs to manage heat release during long heating hours, this study proposed a new ETSD that uses K₂CO₃–Na₂CO₃ for high-temperature storage to match the off-peak hours and thereby gain potential economic benefits. This study used experimental and simulation methods to investigate the ETSD’s temperature distribution. An operational strategy was also proposed to achieve more efficient temperature distribution and higher economic benefits. The ETSD with two steel plates and two insulation layers with a power rating of 1.6 kW was found to be the optimum structure, due to its improved heat storage rate (2.1 °C/min), uniform temperature, and material heat resistance (<750 °C). An energy analysis, economic analysis, and a 7-day cycling operation performance of the device were then conducted by comparing the proposed ETSD with a traditional electric heater. The results revealed that the proposed ETSD released 53.4% of the stored energy in the room, and stored 48.6% of it during valley electric time. The total cost of the proposed ETSD was consistently lower than the traditional electric heater in the second heating season (by the 213th day). The efficiency of its valley heat storage for users was 37.2%. Overall, this study provides valuable insights into the development and practical applications of ETSD systems for space heating. Full article

Nickel plating electrolytes prepared by using a simple salt solution can achieve nickel plating on laser-induced graphene (LIG) electrodes, which greatly enhances the electrical conductivity, electrochemical properties, wear resistance, and corrosion resistance of LIG. This makes the LIG–Ni electrodes well suited for electrophysiological, strain, and electrochemical sensing applications. The investigation of the mechanical properties of the LIG–Ni sensor and the monitoring of pulse, respiration, and swallowing confirmed that the sensor can sense insignificant deformations to relatively large conformal strains of skin. Modulation of the nickel-plating process of LIG–Ni, followed by chemical modification, may allow for the introduction of glucose redox catalyst Ni₂Fe(CN)₆ with interestingly strong catalytic effects, which gives LIG–Ni impressive glucose-sensing properties. Additionally, the chemical modification of LIG–Ni for pH and Na⁺ monitoring also confirmed its strong electrochemical monitoring potential, which demonstrates application prospects in the development of multiple electrochemical sensors for sweat parameters. A more uniform LIG–Ni multi-physiological sensor preparation process provides a prerequisite for the construction of an integrated multi-physiological sensor system. The sensor was validated to have continuous monitoring performance, and its preparation process is expected to form a system for non-invasive physiological parameter signal monitoring, thus contributing to motion monitoring, disease prevention, and disease diagnosis. Full article

More and more attention is being paid to the influence of powder mixing on the mechanical properties and corrosion resistance of WC-based cemented carbides. In this study, WC was mixed with Ni and Ni/Co, respectively, by chemical plating and co-precipitated-hydrogen reduction, which are labelled as WC-Ni^EP, WC-Ni/Co^EP, WC-Ni^CP and WC-Ni/Co^CP, respectively. After being densified in a vacuum, the density and grain size of CP were denser and finer than those of EP were. Simultaneously, the better mechanical properties of flexural strength (1110 MPa) and impact toughness (33 kJ/m²) were obtained by WC-Ni/Co^CP due to the uniform distribution of WC and binding phase and solid solution enhancement of the Ni-Co alloy. In addition, the lowest self-corrosion current density of 8.17 × 10⁻⁷ A·cm⁻², a self-corrosion potential of −0.25 V and the biggest corrosion resistance of 1.26 × 10⁵ Ω in 3.5 wt % NaCl solution were obtained by WC-Ni^EP because of the presence of the Ni-Co-P alloy. Full article

In the present work, a low-pressure chemical vapor deposition (LPCVD) Ti_0.17Al_0.83N and state-of-the-art arc ion plating PVD-Ti_1−xAl_xN (x = 0.25, 0.55, 0.60, 0.67) coatings were deposited on cemented carbide substrate. The morphological, structural, and electrochemical properties of LPCVD-Ti_0.17Al_0.83N and PVD-Ti_1−xAl_xN coatings were compared. The X-ray diffraction (XRD) results and scanning electron microscopy (SEM) images revealed that the LPCVD-Ti_0.17Al_0.83N coating had a face-centered cubic (fcc) structure, while presenting a crack-free surface morphology and a compressive residual stress of −131.9 MPa. The PVD coatings with a composition of x ≤ 0.60 had an fcc structure, while the PVD-Ti_0.33Al_0.67N coating consisted of fcc and w-AlN phases. The results of the electrochemical corrosion test showed that the LPCVD-Ti_0.17Al_0.83N coating had the lowest corrosion current density in a 3.5 wt.% NaCl solution. After a 20-day immersion corrosion test in a 5 mol/L HCl solution, the LPCVD-Ti_0.17Al_0.83N coating displayed higher stability than the PVD-Ti_1−xAl_xN coating. The results of electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) analysis revealed that more uniform and denser passivation film, as well as higher Al₂O₃ proportion in the Al₂O₃/TiO₂ composite passive layer, led to the outstanding corrosion resistance of the LPCVD-Ti_0.17Al_0.83N coating. Full article

Layered perovskite-type semiconductor La₂Ti₂O₇ has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La₂Ti₂O₇ with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co₃O₄ nanoparticles on the surface of n-type plate-like La₂Ti₂O₇. The effects of Co₃O₄ loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co₃O₄/La₂Ti₂O₇ possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co₃O₄ exhibits the highest hydrogen evolution rate of 79.73 μmol·g⁻¹·h⁻¹ and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co₃O₄ ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La₂Ti₂O₇-based heterojunctions for photocatalytic hydrogen evolution. Full article

The Al coatings achieved via electrodeposition on a Cu electrode from AlCl₃-NaCl-KCl (80–10–10 wt.%) molten salts electrolyte with Tetramethylammonium Chloride (TMACl) and Sodium Iodide (NaI) additives is reported. The effect of the two additives on electrodeposition were investigated by cyclic voltammetry (CV), chronopotentiometry (CP), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results reveal that compact and smooth Al coatings are obtained at 150 °C by the electrodeposition process from the electrolyte with 1% TMACl and 10% NaI. The Al coatings exhibit great corrosion resistance close to that of pure Al plate, with a corrosion current of 3.625 μA. The average particle size is approximately 2 ± 1 μm and the average thickness of the Al layer is approximately 7 ± 2 μm. The nucleation/growth process exhibits irrelevance with TMACl or NaI during the electrodeposition of Al. TMACl cannot affect and improve the electrodeposition effectively. However, the addition of TMACl and NaI can intensify the cathodic polarization, producing an inhibition of Al deposition, and contribute to form uniform Al deposits. This can increase the conductivity and facilitate in refining the size of Al particles, contributing to forming a continuous, dense and uniform layer of Al coating, which can be used as effective additives in molten salts electrolyte. Full article

In order to study the effect of nano-CeO₂ particles doping on the electrochemical corrosion behavior of pure Ni-Fe-Co-P alloy coating, Ni-Fe-Co-P-CeO₂ composite coating is prepared on the surface of 45 steel by scanning electrodeposition. The morphology, composition, and phase structure of the composite coating are analyzed by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion behavior of the coatings with different concentrations of nano-CeO₂ particles in 50 g/L NaCl solution is studied by Tafel polarization curve and electrochemical impedance spectroscopy. The corrosion mechanism is discussed. The experimental results show that the obtained Ni-Fe-Co-P-CeO₂ composite coating is amorphous, and the addition of nano-CeO₂ particles increases the mass fraction of P. With the increase of the concentration of nano-CeO₂ particles in the plating solution, the surface flatness of the coating increases. The surface of Ni-Fe-Co-P-1 g/L CeO₂ composite coating is uniform and dense, and its self-corrosion potential is the most positive; the corrosion current and corrosion rate are the smallest, and the charge transfer resistance is the largest, showing the best corrosion resistance. Full article

As part of an effort to characterize clusters and intermediate phases likely to be encountered along solution reaction pathways that produce iron and aluminum oxide-hydroxides from Fe and Al precursors, the complete structure of Al₁₀O₁₄(OH)₂ (akdalaite) was determined from a combination of single-crystal X-ray diffraction (SC-XRD) data collected at 100 K to define the Al and O positions, and solid-state nuclear magnetic resonance (NMR) and neutron powder diffraction (NPD) data collected at room temperature (~300 K) to precisely determine the nature of hydrogen in the structure. Two different synthesis routes produced different crystal morphologies. Using an aluminum oxyhydroxide floc made from mixing AlCl₃ and 0.48 M NaOH, the product had uniform needle morphology, while using nanocrystalline boehmite (Vista Chemical Company Catapal D alumina) as the starting material produced hexagonal plates. Akdalaite crystallizes in the space group P6₃mc with lattice parameters of a = 5.6244(3) Å and c = 8.8417(3) Å (SC-XRD) and a = 5.57610(2) Å and c = 8.77247(6) Å (NPD). The crystal structure features Al₁₃O₄₀ Keggin clusters. The structural chemistry of akdalaite is nonideal but broadly conforms to that of ferrihydrite, the nanomineral with which it is isostructural. Full article