Double-layer Metal Research Articles

An amino acid-functionalized coordination polymer of Cd(II) as a fluorescent probe detecting Cu(II) ion

Cd(II) complex 1, namely {[Cd(HL)]·CH3OH}n was design as a new fluorescence probe for measuring concentration of Cu2+ ion in aqueous solution. Complex 1 is a 3,6-connected double-layered porous metal–organic framework, which was synthesized by optimizing the ratio of Cd(OH)2 and a new ligand 4'-(((1-carboxyethyl)amino)methyl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3L) under solvothermal conditions. It not only had good thermal and solvent stabilities, but also displayed a strong solid-state fluorescence centered at 375 nm with a moderate quantum yield of 37.12% under excitation at 275 nm. More importantly, its fluorescence could be obviously quenched by the addition of Cu2+ ion. The fluorescence quenching may be caused by the weak coordination interaction between Cu2+ and the uncoordinated imino N in ligand (HL)2–, as well as the slightly competitive absorption of excitation light by Cu2+. In the low concentration range of Cu2+ ion, the fluorescence quenching efficiency of complex 1 is closely related to the concentration of Cu2+ ion, and the relationship between fluorescence quenching efficiency and the concentration of added Cu2+ ion could be well fitted by Stern-Volmer equation with KSV being 1.589 × 104 M−1 and the detection limit for Cu2+ ion being 5.7 μM. Our case may provide potential applications for the detection of Cu2+ ion in daily domestic water.

A Cu-Ag double-layer coating strategy for stable and reversible Zn metal anodes

Structuring a stable artificial coating to mitigate dendrite growth and side reactions is an effective strategy for protecting the Zn metal anode. Herein, a Cu-Ag double-layer metal coating is constructed on the Zn anode (Zn@Cu-Ag) by simple and in-situ displacement reactions. The Cu layer enhances the bond between the Ag layer and Zn substrate by acting as an intermediary, preventing the Ag coating from detachment. Concurrently, the Ag layer serves to improve the corrosion resistance of Cu metal. During plating, the initial Cu sheets and Ag particles on the surface of Zn@Cu-Ag electrode gradually transform into a flat and smooth layer, resulting in the formation of AgZn, AgZn3, and (Ag, Cu)Zn4 alloys. Alloys play a multifunctional role in inhibiting dendrite growth and side reactions due to decreased resistance, low nucleation barrier, enhanced zincophilicity, and strong corrosion resistance. Consequently, the Zn@Cu-Ag symmetric cell exhibits continuous stable performance for 3750 h at 1 mA cm−2. Furthermore, the Zn@Cu-Ag||Zn3V3O8 full cell achieves an initial capacity of 293.4 mAh g−1 and realizes long cycling stability over 1200 cycles. This work provides new insight into the engineering of an efficient artificial interface for highly stable and reversible Zn metal anodes.

Analysis and Verification of Shielding Effectiveness Enhancement of Double-Layer Metal Mesh Conductive Film

Analysis and Verification of Shielding Effectiveness Enhancement of Double-Layer Metal Mesh Conductive Film

A kind of numerical model combined with genetic algorithm and back propagation neural network for creep-fatigue life prediction and optimization of double-layered annulus metal hydride reactor and verification of ASME-NH code

The safety and stability of metal hydride reactor (MHR) structure are significantly important for normal operations of hydrogen isotope storage and supply system. Moreover, considering that the experiments of studying the fatigue and creep properties of MHR structure are always time, money, difficulty and energy consuming. To further improve the service life of MHR as well as lower the failure risk, this paper proposes a system integration method based on ASME code validation, which combines genetic algorithm (GA) and back propagation neural network (BPNN) for rapid assessment of creep-fatigue life (CFL) and optimal design of structural parameters. First, numerical simulation is applied to perform thermal-mechanical coupled finite element analysis and verified by ASME code. Then, parametric sensitivity analysis and experimental design of parameter-based training set based on Taguchi method were performed, and response values are obtained from physical models combined with numerical simulations. Finally, a parametric optimization procedure combining BPNN and GA is developed based on the training data. In the workflow, parametric data flow is passed through the experimental design, numerical simulation, prediction and optimization processes. The results show that the proposed BPNN proxy model based on ASME code validation has good performance in predicting the life of MHR. Based on this, the life of the MHR is improved by 8% compared to the reference sample.

The curvature mathematical modeling of the double-layer metal clad plate by the asynchronous rolling

The curvature mathematical modeling of the double-layer metal clad plate by the asynchronous rolling

Highly Transparent Ka-/W-Band Electromagnetic Shielding Films Based on Double-Layered Metal Meshes.

An electromagnetic (EM) wave-shielding film exhibiting high performance in high-frequency bands, such as the Ka- and W-bands, was fabricated by using double-layered metal meshes. The double-layered shielding (DLS) film consists of metallic micromesh and nanomesh electrodes (NMEs) on the upper and lower surfaces of a poly(ethylene terephthalate) (PET) film, respectively. The micromesh electrodes (MMEs) were fabricated such that they possessed a thickness higher than the line width, and they thus exhibited excellent electromagnetic wave-shielding performance in addition to optical transmittance. Moreover, the nanomesh electrodes helped prevent the deterioration of the shielding performance owing to the increase in frequency, which was possible by decreasing the aperture size of the mesh-type electrodes. The shielding effectiveness (SE) of the double-layered metal-mesh film was evaluated by using a shielding measurement system that is optimized for high frequencies. In addition, optical transmittance and flexibility tests were conducted. The results confirm that the double-layered shielding film exhibited a shielding effectiveness of more than 50 dB at an optical transmittance of 90% and a stable bending resistance of up to 5000 cycles at a radius of curvature of 6 mm. Double-layered metal-mesh films with such excellent performance are expected to be widely used in diverse applications such as the automobile, medical, and military industries.

Activation of persulfate by magnetic Mg/Mn–layered double oxide–doped biochar composite for ciprofloxacin removal and bacterial inactivation

Removal of antibiotics and bacteria from wastewater is an effective approach to test the efficacy of catalyst and thus address the issues of water contamination. In this study, a stable magnetic Mg/Mn–layered double oxide–doped biochar composite (MgMnLDO–MBC) was prepared using Lentinula edodes substrate. This composite could further effectively activate the persulfates (PS), such as peroxymonosulfate (PMS) and peroxydisulfate (PDS). MgMnLDO coupling endowed BC and magnetic biochar (MBC) with enhanced surface areas, adsorption sites, and free radicals, which facilitated the improvement of catalytic activity of MgMnLDO–MBC/PS system toward pollutants. MgMnLDO-MBC/PMS system could remove 90.8% of ciprofloxacin (CIP) with 2.8 times the removal efficiency of MBC/PMS system. Density functional theory (DFT) calculation and intermediate analysis showed that the synergistic effect of nucleophilic, electrophilic, and radical active species–mediated reactions improved the removal performance of MgMnLDO–MBC/PMS system. MgMnLDO–MBC/PDS system could efficiently kill 97.6% Escherichia coli and 99.7% Staphylococcus aureus, and destroy the existing biofilms. The effects of composite concentration, PMS loading, pH, temperature, common anions, and humic acid on removal efficiency were also evaluated. After five consecutive cycles, MgMnLDO–MBC/PS system still exhibited high catalytic performance toward CIP removal and bactericidal ability. Results of quenching and electron spin resonance (ESR) showed that ·SO, ·OH, 1O2, and charge transfer were together involved in CIP removal, with ·SO playing a major role. Furthermore, the double–layered metal oxide (LDO) and MBC present in MgMnLDO–MBC composites exhibited a strong synergistic effect in the catalytic process, which resulted in higher reactivity and lower leaching rate of metal ions. In this study, an environment–friendly catalyst was prepared using industrial waste and its efficiency for removal of antibiotics and bacteria from wastewater was verified.

Impact of Geometric Parameters on Spring-Back Deformation in Double-Layer Metal Sheet Bending with an L-Shaped Die

This study delves into the intricate dynamics of the return deformation process in double-layer metal sheet stamping on an L-shaped die, focusing on the pivotal influence of punch and die size parameters. The specific parameters under scrutiny include die radius, die clearance, and plate length. Employing a comprehensive methodology, this research conducts finite element simulations using Abaqus software, ensuring both data collection requirements and implementation feasibility are met. The simulation results are rigorously compared with the published data from a seminal comparative study [1], providing a critical point of reference for analysis. The findings of this investigation illuminate a profound similarity in the impact of three critical parameters, namely die radius, degree of mold opening, and plate length, on the degree of spring-back deformation in the L-bending of SPCC double-layer materials. This outcome not only substantiates and extends the existing body of knowledge but also offers novel insights into the interplay of these parameters in the double-layer metal sheet stamping process, thus contributing significantly to the field of manufacturing and process optimization.

Thermal sensing performance analysis, preparation and application of bimetallic layer MFBG

The FBG(fiber Bragg grating) can be embedded in metal to form smart structure, and to protect the FBG, the surface can be coated with high melting point metal such as Ni. MFBG(metalized FBG) will affect the temperature sensing performance of the FBG. In this paper, the thermal sensing performance of MFBG with single and double metal layers is investigated and the main factors affecting its temperature sensitivity and temperature response are analyzed. The thermal sensitivity of the MFBG gradually stabilizes as the thickness of the metal layer increases. The Ni-Ti MFBG (double-layer MFBG with Ni as the outer metal and Ti as the inner metal) was fabricated by magnetron sputtering and electroplating thickening, and a comparative thermal sensing performance experiment was conducted together with the bare FBG. Metallization of the FBG can improve the temperature sensitivity of the FBG. Samples with different metal layer thicknesses were subjected to thermal tests from 0 to 70 °C, the obtained data verified the soundness of the presented model. To verify the temperature sensing performance of the prepared Ni-Ti MFBG, it was embedded in a three-phase induction motor and the internal temperature of the motor was monitored. The experiments show that the prepared Ni-Ti MFBG has good temperature sensing performance and can accurately sense the motor temperature.

Mechanism insight into the enhanced photocatalytic purification of antibiotic through encapsulated architectures coupling of crystalline Cu2O/amorphous TiFe layer double hydroxide

Amorphous materials are one of the important candidates for improving heterogeneous photocatalysts because of their unique electronic structures and abundant catalytic sites originating from disorder atomic arrangements. However, there is still much room for the development of new crystalline/amorphous heterogeneous composites for photocatalytic application. Hence efficient synthetic strategies for preparing new crystalline/amorphous heterojunctions are highly desired. Herein, we have realized the deep optimization of photocatalytic activity by fabricating crystalline/amorphous Cu2O/Ti-Fe layer double hydroxide (LDH) heterojunctions. Thanks to the typical Z-scheme mechanism originating from the crystalline/amorphous interfaces, the photocharge separation and catalytic active sites obviously enhance compared to single Cu2O and LDH counterparts. As expected, the photocatalytic removal of tetracycline (TC) of the as-prepared Cu2O/Ti-Fe LDH was over 5.2 and 2.2 times those of the pristine Cu2O nanospheres and Ti-Fe LDH nanosheets. This work illustrates the origin of crystalline Cu2O nanospheres encapsulated in amorphous Ti-Fe layer double hydroxide nanosheets for enhanced photocatalytic activity driven by visible light, and provide a general Cu2O-templated solution-phase synthetic method for the synthesis of novel double-metal layer double hydroxide amorphous nanostructures.

Suppression effects of energy-absorbing materials on natural gas explosion in utility tunnels

The energy-absorbing material of metal foam have enormous potential in mitigating the consequences of natural gas explosion disaster in urban utility tunnels. When double-layer metal foam with different pore structures of first larger pores and then smaller pores (LP-SP model), the suppression efficiency of explosion overpressure can reach more than 60% and is 2–3 times that of first smaller pores and then larger pores (SP-LP model), and the error between that and that of the same thickness all with smaller pore structure is only 0.86%. Similarly, the metal foams with the LP-SP model can block the explosion flame propagation chain entirely, while reversing the combination order weakens the suppression effect on the explosion flame. Two suppression mechanisms of double-layer metal foam, including the Sudden Shrinkage Effect (SSE) of the LP-SP model and the Amplification Effect (AE) of the SP-LP model. The metal foam barrier device based on SSE is designed for utility tunnels, which can take effect within 0.1 s under electromagnetic force and gravity. This study can provide scientific theoretical support for designing gas explosion suppression measures in utility tunnels.

Heterointerface construction for permalloy microparticles through the surface modification of bilayer metallic organic frameworks: Toward microwave absorption enhancement

Reasonable heterointerface modification can effectively regulate and enhance the microwave absorption of electromagnetic materials. The surface of magnetic permalloy (PM) microparticles is modified herein by coating double-layer metal organic frameworks (MOF), which are composed of a 2-methylimidazole cobalt salt (ZIF-67) layer and a 2-methylimidazole zinc salt (ZIF-8) layer. A stable heterointerface structure with cobalt/carbon (Co/C) and zinc/carbon (Zn/C) layers is formed on the surface of PM microparticles after pyrolysis. These particles include two types of composite particles of PM solely encapsulated by ZIF-67 or ZIF-8, PM@ZIF67 and PM@ZIF8, respectively, and two types of composite PM particles with a double-layered MOF outer shell structure obtained by exchanging the coating sequence (PM@ZIF8@ZIF67 and PM@ZIF67@ZIF8). Furthermore, the thermal decomposition temperature has a significant impact on the surface morphology and magnetic properties of the composite particles. After pyrolyzing at 500 °C, the PM@ZIF67@ZIF8 samples exhibit the highest microwave absorption performance among these samples. Specifically, the minimum reflection loss and effective absorption bandwidth of PM@ZIF67@ZIF8 after pyrolyzing at 500 °C can reach −47.3 dB at a matching thickness of 3.8 mm and 5.3 GHz at a matching thickness of 2.5 mm, respectively. A heterointerface with an electrical field orientation is created in the PM@ZIF67@ZIF8 particles, which effectively enhances the interface polarization and dipole polarization. Furthermore, the formation of a three-dimensional carbon network after pyrolysis is also useful for optimizing impedance matching and enhancing magneto-electric synergism.

Dynamic adjustable metalens based on a stretchable substrate with a double-layer metal microstructure.

Based on the impedance-matching theory, a double-layer metal structure dynamical focusing cylindrical metalens with a stretchable substrate was designed at the operation frequency of 0.1THz. The diameter, initial focal length, and NA of the metalens were 80mm, 40mm, and 0.7, respectively. The transmission phase of the unit cell structures could cover 0-2π by changing the size of the metal bars, and then the different unit cells were spatially arranged as the designed phase profile for the metalens. When the stretching range of the substrate was about 100%-140%, the focal length changed from 39.3mm to 85.5mm, the dynamic focusing range was about 117.6% of the minimum focal length, and the focusing efficiency decreases from 49.2% to 27.9%. Then, by rearranging the unit cell structures, a dynamically adjustable bifocal metalens was numerically realized. Using the same stretching ratio, compared to a single focus metalens, the bifocal metalens can provide a larger focal length control range.

Performance enhancement of coated conductor magnet with double-layer metal insulation

A double-layer metal-insulation method using brass sheets as the double-layer insulators is proposed in this paper. It can enhance the contact resistivity while preserving greater thermal conductivity merit. The underlying mechanism of the contact resistivity enhancement is to increase the number of contact surfaces and to degrade the contact quality between the insulators. Then, we wound a single-layer brass-insulation coil and a double-layer brass-insulation coil to compare their contact resistivities, and confirmed the effectiveness of the double-layer metal-insulation method. Furthermore, since the capacity to withstand the overcurrent is weakened with the increasing contact resistance of the metal-insulation coil, we further investigated the influence of the contact surface resistivity distribution on the coil performance under different scenarios to optimize the double-layer metal-insulation coil for receiving superior thermal stability. The simulation results indicate that dominant second contact surface resistivity and minimal first and third contact resistivity is the optimal design for the double-layer metal-insulation coil to receive the best thermal stability, irrespective of the cooling environment, contact resistivity magnitude, operating current and coil dimension. In addition, with regard to the thermal performance differences caused by the contact surface resistivity distribution, we found that the increment of contact surface resistivity and the overcurrent enlarged the distinctions at different levels.

Optimization design of the sound absorbing structure of double-layer porous metal material with air layer based on genetic algorithm.

An acoustic absorption structure of a double-layer porous metal material with air layers is proposed. The Johnson-Champoux-Allard (JCA) model combined with the transfer matrix method (TMM) was used to establish the theoretical calculation model of the sound absorption coefficient (SAC). Meanwhile, the SAC between 500 and 6300 Hz were measured with an impedance tube. The errors between the theoretical and experimental values were compared to illustrate the good predictability of the theoretical model within the inverse estimations of the transport properties. The effects of the material placement order, material thickness, and cavity depth on the sound absorption performance from 200 to 5000 Hz were analyzed using the theoretical model. Further, a multi-objective function genetic algorithm was used to optimize the porous material's thickness and SAC to obtain an acoustic structure with a smaller thickness and higher sound absorption. A series of optimal solutions were obtained for acoustic structures with a total thickness of less than 70 mm. When the total thickness of the foam metal was 33.57 mm, the average SAC reached 0.853, which was significantly lower than the total thickness of the previous experiments. The multi-objective function genetic algorithm can provide a reliable solution for the optimal design of most sound-absorbing structures.

On the Use of Metal-Only Polarization Rotation Elements for Reflectarray Designs

A reflectarray antenna employing metal-only polarization rotation elements is proposed in this letter. The element is composed of double metallic layers separated by an air gap and rotates the reflection wave polarization orthogonally with respect to that of the incidence wave. By tuning the structural dimension, a pair of elements with 90° phase difference are obtained. These two elements together with their mirroring images can be employed as a 2-bit phase shifter with 0°, 90°, 180°, and 270° phase shift from 9 to 10.8 GHz. For proof-of-concept, a metal-only reflectarray containing 225 unit-cells is developed and tested. According to experimental results, the 1 dB and 3 dB gain bandwidth of the metal-only reflectarray are 19% and 38% respectively while the peak aperture efficiency is 34%. These encouraging features demonstrate that reflectarrays can be successfully designed with metal-only polarization rotation elements and present a good potential for space applications.

Development of hydrothermal corrosion model and BWR metal coating for CVD SiC in light water reactors

SiC/SiC fiber composites with CVD SiC overcoats are potential candidates for light water reactor advanced accident tolerant cladding materials. Understanding its corrosion kinetics in Light Water Reactor (LWR) conditions is essential to evaluate the concept's viability. Existing models only account for the temperature and oxygen concentration effect on the hydrothermal corrosion behavior applicable to LWR operating conditions. However, the development of a general corrosion rate for CVD SiC that accounts for the impact of irradiated microstructure, flow rate, electrical resistivity, pH, and surface roughness is critical for the practical realization of SiC/SiC-based cladding concepts. After a rigorous experimental campaign, this work updates the existing hydrothermal corrosion model to predict hydrothermal corrosion in LWRs. Numerical radiation and coolant chemistry analysis for LWRs conducted based on the updated corrosion kinetic models suggests that CVD SiC is likely a viable environmental barrier coating for Pressurized Water Reactors while questionable for Boiling Water Reactors (BWR) when the effect of irradiation damage on SiC corrosion is considered. An effective mitigation strategy for the double-layer metal coating is proposed for BWR applications. The double-layer metal coating comprising a FeCrAl overcoat with an intermediate Cr bond coating was observed to provide a stable protective barrier against SiC dissolution in BWR conditions. The proposed metal coating was also fully adherent following quench and burst tests.

A Liquid Crystal Tunable Metamaterial Unit Cell for Dynamic Metasurface Antennas

This communication presents a liquid crystal (LC)-based electronically tunable metamaterial unit cell that can serve as a building block for dynamic metasurface antennas (DMAs). The metamaterial unit cell was designed based on a complementary electric-inductive-capacitive (cELC) resonator, whose structure was modified into double metal layers for ease of loading the LC mixture. The equivalent capacitance, and thus the transmission coefficient of the metamaterial unit cell, can be tuned by external biasing voltages. The metamaterial unit cell couples to the transverse magnetic (TM) field, making it easy to be embedded into waveguide-fed structures such as microstrip lines or parallel-plate waveguides. In addition, it is individually addressable, which meets the design requirement of DMAs. Experimental results show that the transmission coefficient of the metamaterial unit cell can be continuously tuned from −2.7 to −6.5 dB at 29 GHz with a biasing voltage swinging from 2.5 to 10 Vrms. The response times are around 150 ms for both switch-ON and swtich-OFF cases.

Gap Measurement of Double-Layer Metal Tube Based on Analytical Solution of Eddy Current Array Under Transmit-Receive Mode

Gap Measurement of Double-Layer Metal Tube Based on Analytical Solution of Eddy Current Array Under Transmit-Receive Mode

Research on the Creep and Fatigue Evaluation Method of the Double-Layered Annulus Metal Hydride Bed Combined with Numerical Modeling and ASME Code

Applied to a hydrogen absorption-desorption cycle, the hydrogen storage bed will experience higher exchange temperatures and variety of mechanical load. Due to the complex structure of the double-layered annulus metal hydride bed and the importance of thermal stress on the failure of a metal hydride bed, the numerical modeling of its hot spot stress was carefully carried out. Moreover, in this paper, an analysis method considering the limit failure mode condition is proposed to deal with the stress analysis in the process of hydrogen absorption and desorption. According to the proposed analysis method, the maximum stress of thermal-structural coupling in the process of hydrogen absorption occurs at about 1/3 along the diameter direction and at the geometric mutation of the connection between the cooling pipe and the main body of the hydrogen storage bed in the process of hydrogen desorption. Apart from that, the hydrogen storage bed is also subjected to thermal-mechanical fatigue by the iterative process of absorption and desorption, and its operating temperature range is in the thermal creep temperature region. Based on the distribution of the stress and temperature, evaluation hot sites were selected and the ASME-NB and ASME-NH codes were used to evaluate fatigue and fatigue creep, respectively. The evaluation showed that the fatigue damage generated during its service life is small, while the creep damage is relatively large and the total damage generated during the service life of the hydrogen storage bed is within the safe range. Aiming at the structure and complex process of a double-layer hydrogen storage bed, creep and fatigue evaluation methods are proposed, various failure modes of hydrogen storage bed are highlighted, and the relationship between process parameters and life is established.