Search

In this paper, an ultra-thin absorber with a total thickness of 9.2 mm is designed and verified at the frequency band of 1–5.34 GHz. The absorber is composed of a layer of metasurface, multi-layered magnetic substrate, a layer of fragmented magnetic structure obtained by improved MOEA/D-GO (Multi-Objective Evolutionary Algorithm based on Decomposition combined with Enhanced Genetic Operators), and a copper back plate. The absorber is achieved by two steps. First, we designed and measured an ultra-thin absorber at 0.78–2.04 GHz by adding a layer metasurface onto the top of a basic multi-layer absorber composed of magnetic materials. The fractional bandwidth (FBW) of the absorber is 89.4%, and the electrical thickness is only 0.024 λ 0 at the lowest operating frequency. Second, to broaden the bandwidth, we use an improved MOEA/D-GO to optimize one magnetic layer of the absorber. The working frequency band of the optimized absorber is 1–5.34 GHz, covering L- (1–2 GHz), S- (2–4 GHz), and partial C-bands (4–8 GHz). Furthermore, we modified the structure of the metasurface to make the absorber polarization-independent. The FBW of the final absorber is 136.4%, and the electrical thickness is 0.031 λ 0 at the lowest operating frequency. The prototype of the absorber is measured, and the experimental results agree well with the simulated performance. The results show that the improved MOEA/D-GO can be used to design and optimize sophisticated electromagnetic (EM) structures with the predesigned properties, and the absorber with ultrathin thickness and light weight verified in this paper have great application potentials in EM compatibility, EM shielding, and radar cross section reduction at the low bands of the microwave spectrum. [ABSTRACT FROM AUTHOR]

In this paper, we report a reconfigurable multifunctional polarization converter (RMPC) based on positive-intrinsic-negative (PIN) diodes, enabling to achieve different functions in different bands and states. The simulations and experiments show that when the PIN diode is off, it acts as a broadband linear polarization (LP) converter at 9.12–15.93 GHz. Simultaneously, when the PIN diode is on, the LP incident wave is converted into a left-handed circular polarization wave at 8.69–11.41 GHz and a cross-polarization wave at 13.40–14.97 GHz, whereas full reflection is obtained at 12.05–12.54 GHz. The RMPC consists of two dielectric plates and three layers of metal copper plates. Finally, a sample was fabricated and measured, the simulated and experimental results were in good agreement. Compared with other works, the RMPC has more working states and wider operating frequency bands, which has an application potential in the field of radar stealth and satellite communication. [ABSTRACT FROM AUTHOR]

Highlights This study introduces an innovative technique for the fabrication of copper‐based polytetrafluoroethylene (PTFE)/graphite self‐lubricating composites. By harnessing the exceptional capabilities of selective laser sintering (SLS), we efficiently create three‐dimensional, continuous, and porous graphite preforms. Following this, the composite is formed through a combination of electroplating and vacuum extrusion methods. Subsequently, PTFE was vacuum impregnated into the microporous structure of the graphite preforms, and the composites were obtained through freeze‐drying, plasticizing, and machining processes. The resulting copper‐based PTFE/graphite self‐lubricating composites exhibit an exceptional blend of properties. Notably, there is a significant reduction in the average coefficient of friction, dropping from 0.14 to 0.02, and a marked decrease in the wear rate, from 1.358 × 10−5 to 1.109 × 10−5 mm3/N·m, as compared to graphite as a standalone lubricant. This represents a substantial improvement in performance, underscoring the effectiveness of the proposed fabrication method. The porous graphite with controllable shape distribution was prepared. Surface copper plating improves surface bonding. Controllable copper matrix composites with double lubricant were prepared. The average friction coefficient is as low as 0.02. [ABSTRACT FROM AUTHOR]

Realizing multiple locked shapes in pre-oriented liquid crystal elastomers (LCEs) is highly desired for diversifying deformations and enhancing multi-functionality. However, conventional LCEs only deform between two shapes for each actuation cycle upon liquid crystal-isotropic phase transitions induced by external stimuli. Here, we propose to regulate the actuation modes and the locked shapes of a pre-orientated epoxy LCE by combining dynamic covalent bonds with cooling-rate-mediated control. The actuation modes can be adjusted on demand by exchange reactions of dynamic covalent bonds. Derived from the established actuation modes, such as elongation, bending, and spiraling, the epoxy LCE displays varied locked shapes at room temperature under different cooling rates. Various mediums are utilized to control the cooling rate, including water, silicone oil, and copper plates. This approach provides a novel way for regulating the actuation modes and locked shapes of cutting-edge intelligent devices. [ABSTRACT FROM AUTHOR]

Direct explosion welding makes it challenging to weld high-strength metals. Interlayer explosive welding was utilized to join the high-strength, low-melting-point aluminum alloy A7075 with the high-strength titanium alloy Ti–6Al–4 V. This method overcomes the challenges of directly welding such metals and widens the range of weldable parameters, thus facilitating more favorable welding conditions. The study effectively demonstrated the interlayer explosive welding process for A7075 with Ti–6Al–4 V using aluminum and copper interlayers. Microstructure and chemical content analysis of the bonded interfaces were conducted through optical microscope, scanning electron microscope, electron backscatter diffraction, and X-ray energy spectroscopy. The investigations found that the upper interfaces were flat and straight in shape, but the lower interfaces were wavy. Interdiffusion of components and compound formation occurred at the welded interface. In addition, grain refining took place at the bonding interface. Vickers hardness was used to measure hardness variations at the welded interface, and the mechanical properties of the bonded interface were examined using tensile shear, bending, and microtensile tests. The results confirm the practicality of interlayer explosive welding in producing high-strength, low-melting-point composites of A7075 and Ti–6Al–4 V. Microstructure analysis and mechanical testing at the weld interfaces of A7075/A1060/Ti–6Al–4 V and A7075/Cu/Ti–6Al–4 V composite plates revealed excellent bonding quality. Notably, compared to A7075/A1060/Ti–6Al–4 V composite plate, A7075/Cu/Ti–6Al–4 V composite plate performs better in mechanical tests, with tensile bending strengths of 137 MPa and 1321 MPa, respectively. Thinner interfacial melting zones were evident in the microstructure of the composite plate with a copper interlayer at the 30 mm explosive thickness parameter, correlating with improved performance in the microtensile test. [ABSTRACT FROM AUTHOR]

The construction of flexible circuits is a crucial and challenging aspect in the design and fabrication of fabric‐based flexible electronics, which hold significant potential for various applications. In this study, we successfully developed high‐precision and durable fabric‐based flexible circuits by ingeniously combining ultraviolet light (UV)‐curing technology with chemical plating. Specifically, a UV coating containing Ag/Fe3O4 catalysts was applied onto polyester fabric surface, followed by printing the designed circuit structure diagram onto the fabric using UV light‐directed curing of the coating, and fabric‐based flexible circuits were then fabricated through chemical plating process. The fabric‐based flexible circuits exhibit only minimal increases in resistance following durability testing, including bending (8000 times), abrasion (2000 times), high and low temperature stability (−30 to 60°C), and high temperature/humidity stability (65°C, RH = 95%, 48 h), which remains consistently stable. This developed technology holds immense potential across various applications for smart wearable devices. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copper plating on graphite surfaces is employed as an effective strategy to enhance the wettability between Cu and graphite, which is otherwise inadequate. To achieve a uniformly coated Cu layer on graphite surfaces, this study utilized rotational electroless plating. Subsequently, the effects of CuSO4 ⋅ 5H2O concentrations (10, 15, 20, and 25 g/L) and reaction solution temperatures (30, 40, 50, and 60 °C) on the uniformity and density of the Cu coating on the graphite surface were investigated. The findings reveal that variations in the concentration of the CuSO4 ⋅ 5H2O have a limited impact on the uniformity and densification of the Cu coating. Specifically, as the concentration of CuSO4 ⋅ 5H2O increases from 10 g/L to 25 g/L, there is a slight decrease in the uniformity and integrity of the Cu coating, with the density of Cu‐coated graphite powder decreasing marginally from 3.646 g/cm3 to 6.642 g/cm3. In contrast, the temperature of the reaction solution has a significant effect on the uniformity and densification of the Cu coating. With an increase in the reaction solution temperature from 30 °C to 60 °C, there is a noticeable deterioration in the uniformity and integrity of the Cu coating, with a decrease in the density of Cu‐coated graphite powder from 3.653 g/cm3 to 6.620 g/cm3. [ABSTRACT FROM AUTHOR]

In today's era of increasing energy constraints, harnessing the power of electromagnetic waves and converting them into directly usable energy has great potential in the field of renewable energy. This paper presents a highly efficient electromagnetic energy harvester with wide operation angles based on metasurface. The metasurface unit comprises four rotated copper rings plated on a Rogers RT5880 substrate. This unique design incorporates a 3.6 kΩ resistor within each of the four-cornered rotating metal rings, effectively emulating the input impedance circuit of a rectifier. Simulation results reveal that the metasurface achieves a remarkable electromagnetic wave harvesting efficiency of up to 92.3% at a frequency of 5.85 GHz. Additionally, it exhibits polarization insensitivity, enhancing its versatility and suitability for wide incident angles, which augments its practicality in various environments. The proposed metasurface energy harvester represents a significant advancement in electromagnetic energy collection technology, offering an efficient and reliable energy harvesting solution that contributes to addressing energy shortages and is applicable across multiple scenarios. [ABSTRACT FROM AUTHOR]

Metalworking methods for silver and silver plated copper artefacts may strongly influence their corrosion behaviour. Various surfaces were generated on sterling silver coupons as well as silver plated copper coupons to simulate traditional shaping techniques and surface finishing procedures on historical silver artefacts. Coupons were either polished by hand, by a fabric disc on a polishing machine, or submitted to a hammering process in reference to the as-received state. All samples were subjected to various aging protocols, such as natural aging, a thioacetamide (TAA) gas test (NBN EN ISO 4538:1995) and a Na2S immersion test (NBN EN ISO 8891:1998). The various surface finishing procedures led to marked differences in the tarnishing behaviour which were evaluated by colorimetry, optical microscopy, and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The current study uses a Finite Element (FE) Method to forecast residual stresses and deformation caused by the GTA welding process. The authors use a 5 mm thick stainless steel plate for the analysis. Residual stress and distortion predictions are made by successfully coupling thermal and mechanical studies. Mechanical and thermal analyses of moving heat source-exposed plates were conducted sequentially. Applications such as ANSYS and SOLIDWORKS are used to do the FE analysis. In transient thermal analysis, the arc's heat input has been modeled using a Gaussian distribution. Consideration of temperature-dependent physical and mechanical parameters is integral to the modeling process. The welding heat in stainless steel welding and how it behaves inside the joint has significant effects in determining the welding joint distortion, mechanical properties, and the weldments fit with the design criteria due to stainless steel thermal properties. Subsequent mechanical analysis is fed the transient thermal histories to the model. Analyzing mechanical systems involves using the big displacement hypothesis. How restrictions influence distortion and residual stresses is quantitatively investigated. The anticipated stresses and distortion values are presented and discussed for various scenarios. Welding distortion was minimized when a copper backing plate was used, as shown by a lower maximum deformation measured compared to situations without the plate. The backing plate reduced maximum stress values and lowered residual stresses. A backing plate also made the fusion zone smaller and the temperature drop from the peak welding temperature to room temperature steeper. According to the research, using a copper backing plate during stainless steel welding may significantly reduce deformation and residual stresses. The results could improve stainless steel welding by choosing the best materials for backing plates and improving welding. Investigation results and the mathematical models of welding simulation can significantly improve stainless steel deformation-reducing techniques in many applications and introduce particular techniques to predicate the impacts of backing plates in such welding processes as food, chemical, Pharmaceutical, Oil and Gas, and water treatment industries. [ABSTRACT FROM AUTHOR]

To address the issues of poor arc erosion resistance and short electrical life of Ag-based electrical contact materials, the surface of carbon fibers was modified by chemical copper plating, and then Ag-based electrical contact materials were prepared by using powder metallurgy technol- ogy. The microscopic morphology of the carbon fiber surface and the surface of the Ag-based elec- trical contact material was characterized by scanning electron microscopy; the overall mass loss was measured and the arc erosion morphology was characterized by arc erosion testing of the Ag- based electrical contact material through the electrical performance simulation open-break sys- tem. The results show that the surface modification of carbon fibers can effectively improve the wettability with Ag substrate; and that the addition of carbon fibers can effectively improve the arc erosion resistance of AgSnO2 electrical contact materials compared with AgSnO2 electrical contact materials without carbon fibers. [ABSTRACT FROM AUTHOR]

Through comparing the distribution of blank holder force (BHF) and stress-strain curve along the radial direction, there has been good forming capability and adaptability in deep drawing with the electro-permanent magnetic (EPM) blank holder (EPMBH) technique. However, whether the BHF technique is applicable for non-ferromagnetic materials has yet to be researched. In the paper, taking 08-Al steel and H62 copper plates as examples, the drawability of ferromagnetic and non-ferromagnetic sheets with EPMBH is investigated. Moreover, a series of confirmatory tests were carried out based on numerical analysis. It found that similar to the deep drawing with ferromagnetic slab, there is slight attenuation on the holding effect for non-ferromagnetic sheets, and the effect of gap on the magnetic attraction caused by the magnetic properties of the plate first increases sharply and then slowly decreases, while its possible failure modes are also wrinkling and rupture due to insufficient BHF and excessive drawing height, respectively. In the experiment, flawless deep-drawing workpieces can be obtained with EPMBH, indicating that EPMBH could meet the forming requirement for ferromagnet and non-ferromagnetic plates and can be controllably adjusted through altering the excitation current of the EPMBH device. The experiment result shows that the optimal excitation current is 14 A for ferromagnetic steel plate and 13 A for non-ferromagnetic copper plate with the same diameter of 110 mm and thickness of 0.8 mm. [ABSTRACT FROM AUTHOR]

Cryptocaryon irritans is a highly detrimental parasite in mariculture, causing significant economic losses to the aquaculture industry of Larimichthys crocea. In recent years, copper and copper alloy materials have been used to kill parasites. In this study, the effect of copper plates on the tomont period of C. irritans was explored. The findings indicated that copper plates effectively eradicated tomonts, resulting in a hatching rate of 0. The metabolomic analysis revealed that a total of 2,663 differentially expressed metabolites (1,032 up-regulated and 1,631 downregulated) were screened in the positive ion mode, and 2,199 differentially expressed metabolites (840 up-regulated and 1,359 down-regulated) were screened in the negative ion mode. L-arginine and L-aspartic acid could be used as potential biomarkers. Copper plate treatment affected 25 metabolic pathways in the tomont, most notably influencing histidine metabolism, retinol metabolism, the biosynthesis of phenylalanine, tyrosine, and tryptophan, as well as arginine and proline metabolism. It was shown that high concentrations of copper ions caused a certain degree of disruption to the metabolome of tomonts in C. irritans, thereby impacting their metabolic processes. Consequently, this disturbance ultimately leads to the rapid demise of tomonts upon exposure to copper plates. The metabolomic changes observed in this study elucidate the lethal impact of copper on C. irritans tomonts, providing valuable reference data for the prevention and control of C. irritans in aquaculture. [ABSTRACT FROM AUTHOR]

This letter presents compact waveguide variable bends incorporating integrated bandpass filters. Two designs have been demonstrated within X‐band (8.2–12.4 GHz) range, using three‐dimensional stereolithography printing and copper plating. The first design utilizes coupled elliptical resonators, while the second employs coupled deformed ellipsoidal resonators. These designs provide both filtering functionality and complex waveguide routing simultaneously, thereby leading to a reduction of total size and loss. This facilitates the design of compact, low‐loss, and multifunctional integrated subsystems. The measured responses (without any tuning) of both waveguide variable bends exhibit excellent performance, with averaged insertion loss of 0.59 and 0.57 dB, and return loss better than 11.9 and 19.8 dB throughout the passband, respectively. Good agreements between the simulated and measured results of the prototype devices successfully validate the feasibility and practicality of the proposed concept. [ABSTRACT FROM AUTHOR]

Among the extensive repertoire of Pāṇḍya dynastic themes, the motif of clash between a Pāṇḍya sovereign and Indra is ubiquitous. This topos, which supposedly originated around middle of the 5th century CE, can be traced to Cilapattikāram XI, 17-30, which celebrates a Pāṇḍya monarch wearing Indra's garland, capturing the clouds, and breaking the god's crown. The narrative was later employed in the Tiruviḷaiyāṭaṟpurāṇam (late 13th century) and its Sanskrit rendering, the Hālāsyamāhātmya (14th-15th centuries), where the actions of the Pāṇḍya kings were inserted in the narratives about the divine līlās of Śiva in Madurai. Since the early phase of the dynasty, this mytheme was employed as a tool of political display in the South. After a survey of the motif in the first phase of the imperial documents, the paper will focus on the reemployment of the category of royal violence in the Teṅkāśi dynastic period (14th-18th centuries CE), using the lens of the official copper plates of the late Pāṇḍya chancery and the previous Sanskrit literary production. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a novel loosely coupled transformer (LCT) with a planar magnetic flux concentrator (MFC) for the wireless power transfer (WPT) in smart grid, which can improve the power of the receiving (Rx) coil. The MFC is a planar copper plate with a radial slit and a center hole, which is made of a printed circuit board (PCB). A simulation model and an experimental platform are built to investigate the performance of the LCT with and without an MFC. The results show that in the case of the transmitting (Tx) side with an MFC, the power of the receiving (Rx) coil increase by 33.82%. Besides, we propose the equivalent T-circuit for the LCT with an MFC. [ABSTRACT FROM AUTHOR]

Despite rechargeable aqueous Zn‐ion batteries (AZIBs) exhibit advantages such as high safety, high specific energy, and low cost, etc, the implementation of Zn anodes is still hampered by insufficient cyclability and grievous side reactions. To improve the cycling stability of the zinc anode, a stable zinc anode/electrolyte interface is needed to suppress dendrite formation and side reactions. Herein, a self‐regulating endogenous organic–inorganic hybrid interface layer (EHI) in situ on the surface of the Zn anode by regulating solvent molecules is constructed. The EHI consists of an organic outer layer containing N─H and ─CH3 and an inorganic inner layer containing ZnO and ZnCO3, which effectively inhibits hydrogen evolution and dendrite growth. Consequently, AZIBs with the EHI achieve a lifespan exceeding 5500 h in 3 mA cm−2, and stripping/plating on copper foils for 600 cycles with an average coulomb efficiency (CE) of 99.47%. This study provides a feasible idea for realizing stable and reversible zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

This article describes the design of the HGND detector (High Granular Neutron Detector) for measuring azimuthal neutron fluxes in the range from 300 to 4000 MeV as well as heavy ions formed in nucleus-nucleus collisions at energies up to 4 AGeV in the BM@N (Baryonic Matter at Nuclotron) experiment on the extracted beam of the JINR Nuclotron, Dubna. The detector consists of 16 layers of plastic scintillation detectors having a cellular structure with copper absorption plates between the layers. The results of measuring the time resolution of scintillation cells using silicon photodetectors are presented. The proposed electronics circuit for reading signals from scintillation cells is described. The results of modeling the acceptance of a neutron detector, the efficiency of neutron detection, the neutron energy resolution, and an estimate of the neutron count rates for the Bi + Bi reaction at an energy of 3 AGeV are presented. [ABSTRACT FROM AUTHOR]

Total solar eclipses occur nearly every 18 months at some place on the Earth but for any given location, it is a rarest of the rare events. In our quest for the records of solar eclipses in Indian inscriptions, chronicles and literature since Antiquity until the close of the nineteenth century, we have come across only very few references where the eclipse is stated as total. In this paper we focus on one such reference, the so-called Kurtakoti Plates from Karnataka, where there is a Grant made on the occasion of a total eclipse of the Sun. The Grant was attributed to the seventh century Chalukyan king Vikramaditya I. Being a copper plate Grant, doubts were raised over its genuineness. The Kurtakoti copper plates may be a later reproduction of the original plates, which may have been damaged or lost. We find that there indeed was a total solar eclipse over Kurtakoti, on 21 April 627 CE, that can fit the Grant. However, it occurred in the times of the King's father, the great Chalukyan King Pulikesi II with whom the details as given in the Grant are more consistent. This eclipse is an independent corroboration of his date of ascension being 610-611 CE. There is no known Indian historical record mentioning an eclipse of the Sun as total but datable still earlier. [ABSTRACT FROM AUTHOR]

The development of protective coatings on copper alloy surfaces represents a critical research direction to enable the widespread industrial application of copper alloys. To improve the corrosion resistance and wear resistance of the copper alloy plates, a Ni-Cr-Co-based multi-principal element alloy coating was prepared via high-velocity oxygen fuel (HVOF). Then, the microstructure, corrosion resistance, and wear resistance of the Ni-Cr-Co coating and the electroplated NiCo coating were analyzed comparatively. The research results show that the phases of the Ni-Cr-Co coating contained face-centered cubic (FCC) solid solution, CrB and M23C6. The NiCo coating exhibited a single-phase FCC solid solution structure. Compared to the NiCo coating, the corrosion current density of the Ni-Cr-Co coating was reduced by 92.1% in NaF solution. A highly protective passive film was formed on the Ni-Cr-Co coating, and its low ΣCSL grain boundary proportion reached as high as 25.7%. Therefore, the Ni-Cr-Co coatings demonstrated superior corrosion resistance. The scratch wear coefficient of the Ni-Cr-Co coating was only 51.9% of that of the NiCo coating, due to the synergistic strengthening of the matrix and hard second phase. This research offers technical support and a theoretical basis foundation for the development of coatings on copper alloys with excellent corrosion resistance and wear resistance. [ABSTRACT FROM AUTHOR]

Reductions in automobile weight and carbon dioxide emission are critical for the further development of the automobile industry. Aluminum is a lightweight material that can replace copper in automobile electronic equipment; therefore, laser welding of aluminum and copper is a subject of extensive research. This study investigates the influence of the laser strategy on the laser welding of aluminum and copper while preventing the formation of brittle Al–Cu intermetallic compounds. Aluminum and copper plates with a length of 20 mm and thickness of 0.3 and 1 mm, respectively, are used for the experiment. A continuous-wave laser with a power of 500 W and a spot beam radius of 150 μm is employed to irradiate the aluminum surface at different scan speeds. An electroless-plated nickel layer is used as a buffer between aluminum and copper, and the experimental results show that it can prevent copper surface damage and the formation of Al–Cu compounds during laser welding. In addition, the simulation and experimental results reveal that the residual thermal stress after laser welding can be reduced by heat treatment at different temperatures prior to laser irradiation. [Display omitted] • Al–Cu compound can be avoided during the laser welding process by the electroless nickel layer. • Residual thermal stress can be decreased by controlling the pre-heat treatment temperature for the metal before the laser weld. • Tension strength of welded joint will be decided by the laser scan speed in the welding process. • The contact area of the Al–Cu interface will affect the residual thermal stress after laser welding. [ABSTRACT FROM AUTHOR]

Traditionally, it has been considered that the Ptolemaic or classical maps from the four editions of Ptolemy's Geography published in Rome (1478, 1490, 1507, and 1508) are apparently indistinguishable at first glance because they have been printed from the same plates. This poses a problem for antiquarians, collectors, and curators who wish to accurately date their copies. Recently, two very comprehensive articles have been published on the different paper watermarks associated with each edition, which would allow for the correct identification of each one. However, there are occasions when the maps do not display watermarks. This article aims to provide some keys to distinguish between the incunabula editions (1478, 1490) and those of 1507–1508 in cases of the absence of watermarks. In this process of detecting differences, we have used digitized images of the maps. The results show small modifications in the copper plates made between the editions of 1490 and 1507/08. Our findings reveal that seven previously unknown reworked maps have been identified. [ABSTRACT FROM AUTHOR]

This paper reports experimental investigations on cold plates made from Low-Temperature Co-fired Ceramic (LTCC) technology for liquid cooling of supercomputer microprocessors. LTCC, a ceramic substrate-based technology with lightweight and ease of fabrication for miniaturization of cooling devices, can be a potential alternative to the existing copper cold plates for future three-dimensional stacked chip architectures. LTCC cold plates were fabricated using ceramic substrates whose thermal conductivity was enhanced using thermal vias. They were embedded with microchannels for liquid with different flow configurations. Their thermal performance is compared against copper cold plates. Deionized (DI) water is used as a coolant. Pressure drop and thermal resistance across different cold plates are measured as per water-cooled data center standards (W3 and W4 class). Obtained experimental results show that the tested LTCC cold plates can be used to cool supercomputer processors. It is concluded that LTCC cold plates can be a potential alternative for existing copper cold plates. [ABSTRACT FROM AUTHOR]

Thin copper plate is widely used in architecture, transportation, heavy equipment, and integrated circuit substrates due to its unique properties. However, it is challenging to identify surface defects in copper strips arising from various manufacturing stages without direct contact. A laser ultrasonic inspection system was developed based on the Lamb wave (LW) produced by a laser pulse. An all-fiber laser heterodyne interferometer is applied for measuring the ultrasonic signal in combination with an automatic scanning system, which makes the system flexible and compact. A 3-D model simulation of an H62 brass specimen was carried out to determine the LW spatial-temporal wavefield by using the COMSOL Multiphysics software. The characteristics of the ultrasonic wavefield were extracted through continuous wavelet transform analysis. This demonstrates that the A0 mode could be used in defect detection due to its slow speed and vibrational direction. Furthermore, an ultrasonic wave at the center frequency of 370 kHz with maximum energy is suitable for defect detection. In the experiment, the size and location of the defect are determined by the time difference of the transmitted wave and reflected wave, respectively. The relative error of the defect position is 0.14% by averaging six different receiving spots. The width of the defect is linear to the time difference of the transmitted wave. The goodness of fit can reach 0.989, and it is in good agreement with the simulated one. The experimental error is less than 0.395 mm for a 5 mm width of defect. Therefore, this validates that the technique can be potentially utilized in the remote defect detection of thin copper plates. [ABSTRACT FROM AUTHOR]

A preparation method of electroless copper electrodes based on elastic nylon fabric for ECG monitoring is proposed to meet the key needs of monitoring accuracy and wearing comfort in this paper. There were 72 rectangular nylon fabric samples involved in the experiment, and three key variables were introduced during the electrode preparation experiment, copper plating time, temperature, pre-stretching, where pre-stretching considered both warp and weft direction. The resistance of 72 samples at 30% stretch state was measured, SEM was used to characterize the copper plated fabric and copper plated fabric ECG electrodes were prepared and evaluated. According to the resistance statistics, the introduction of pre-stretching in the weft direction can bring better copper plating effects, and one sample (which was marked as D20/weft-1) showed the best electrical conductivity in the groups. Combined with SEM images, they all proved the success of copper plating on nylon fabric and that relatively low temperature and appropriate time are beneficial to copper plating. Simultaneously SEM inspection of MΩ-level high-resistance samples revealed that some of the copper plated particles were incompletely covered or peeled off. Finally, evaluating ECG waveforms and signal-to-noise ratios using fabric electrodes in natural and chest expansion state. Results showed that the fabric electrodes prepared from sample D20/weft-1 with excellent conductivity almost have the same performance as traditional Ag/AgCl electrodes. This study provides a cost-effective method and low-cost alternative for electrodes to record high-quality ECG both at home and in the clinic. [ABSTRACT FROM AUTHOR]

This study aimed to perform friction stir welding experiments using a 2-mm-thick copper plate. The tool's rotating speed (ω) and transversing speed were 800–1200 rpm and 200 mm/min, respectively. The impact of the tool's transversing speed on the properties of welded copper was analyzed while keeping the transversing speed constant. Analyzing the experimental results, it is evident that the metallographic microstructure of the welding zone undergoes similar changes at different tool rotation speeds. Specifically, the grain in the welding core zone becomes refined, while the grain near the return side appears larger. The region is the thermomechanically affected zone and heat affected zone, which experiences less agitation from the tool but undergoes compression from the matrix metal, resulting in the grain size being larger than that of the welding zone but smaller than that of the matrix metal. The same was true for the advancing side. The tensile strength of the sample, which was 266.2 MPa, exhibited a high degree of consistency with that of the base metal when the tool's ω value reached 800 rpm. The hardness of each sample exceeded that of the base metal. The hardness of the sample increased by 133.2% to 185.9 HV0.2 when the tool's ω value was set at 1000 rpm, surpassing that of the base metal. The friction coefficient of each sample was lower than that of the base metal. The friction coefficient in the welding zone, which is merely 0.21, represents less than half of that in the base material, which is 0.55. The friction stir welding technique has significantly enhanced copper's mechanical properties, facilitating its widespread application. [ABSTRACT FROM AUTHOR]

In the current work, the chemical etching process and hydrothermal method were used to create bio‐inspired superhydrophobic fluorine‐free tin oxide nanostructures on copper plates. Taguchi's experimental design was also used in investigating coating wettability characteristics based on fabrication parameters. Statistical analysis results demonstrated that the optimal superhydrophobic sample with a water contact angle of 163.40° ± 1.42° and contact angle hysteresis of 3.00° ± 0.80° could be fabricated under the following conditions: sodium hydroxide (2.00 M) as an etching solution, urea‐to‐tin chloride ratio 2.5:1, and 2.00 h reaction times. The effects of each synthesis parameter on the obtained sample's superhydrophobicity were evaluated through multiple one‐variable‐at‐a‐time experiments. Testing the chemical stability of the optimal sample revealed that it was more resistant to deterioration in an alkaline environment (8–10) than in an acidic environment (4–6). The resulting superhydrophobic sample was analyzed by a delay test for water droplets freezing on its surface to determine whether ice formed and accumulated. The created bio‐inspired honeycomb‐like nanocoating demonstrated exceptional mechanical robustness and good anti‐icing performance after 10 consecutive icing cycles. These results indicated that superhydrophobic coatings could be easily and economically produced without using fluoropolymers and silanes on aluminum substrates. [ABSTRACT FROM AUTHOR]

In 2021, Swansea University commissioned Black Mountains Archaeology Ltd to undertake a community archaeological excavation as part of a National Lottery Heritage Funded activity plan. The excavation was undertaken on the site of the former Hafod Plate Rolling Mill in Swansea, South Wales, UK, within which copper plates intended for both national and international shipment were produced between 1910 and 1980. The rolling mill represented one of the largest structures within the Lower Swansea Valley — also known as 'Copperopolis'. Moreover, the mill formed part of the Hafod (and later Hafod-Morfa) Copperworks — one of the largest copper production sites in the world at the time. Within this article, the results of the 2021 excavation will be detailed. During the excavation, features associated with steam power supply, annealing, pickling and finishing were recorded. By comparing the excavation results with available cartographic and documentary evidence of the copperworks, this article outlines a detailed picture of the operations once conducted within the rolling mill, therefore bringing the mill back to life. [ABSTRACT FROM AUTHOR]

The current study aims to meet Sustainable Development Goal (SDG)-12 sustainable consumption and production for electroless copper deposition. The study involves replacement of non-biodegradable chemicals with biodegradable materials. The present work utilises biodegradable D-Mannitol and eco-friendly copper methane sulphonate salt. The bath was stabilised with 2, 2′-dipyridyl and cetrimide. Gravimetric analysis and electrochemical studies viz. anodic polarisation, Tafel polarisation, cyclic voltammetry and impedance spectroscopy were carried out. Deposit morphology and structure were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). 2,2′-dipyridyl and cetrimide were found to reduce the speed of chemical reduction of copper (II) to copper which helps to improve the stability of the bath at higher pH. [ABSTRACT FROM AUTHOR]

Electromagnetic shielding plastics with different mass fractions were prepared by melt blending three kinds of silver-coated copper powder (Ag@Cu) with ethylene-vinyl acetate copolymer (EVA). The effects of different mass fractions and particle sizes of Ag@Cu on the electrical conductivity, shielding properties and mechanical properties of EVA-based electromagnetic shielding plastics were investigated. EVA-based electromagnetic shielding plastics were toughened by maleic anhydride grafted ethylene-octene copolymer/ethylene-octene copolymer (POE-g-MAH/POE) toughening masterbatch and polyisobutylene (PIB)/terpene toughening masterbatch, respectively, to obtain highly filled electromagnetic shielding plastics. The results show that with the increase of Ag@Cu content, the electrical conductivity of EVA-based electromagnetic shielding plastics increases, while the mechanical properties decrease. The percolation threshold of the composites decreases with the increase of filler particle size. When the Ag@Cu filling content is 80%, the shielding effectiveness increases with the increase of filling particle size. Compared with POE-g-MAH/POE, the toughening effect of PIB/terpene is the best, the elongation at break is increased to 187.3%, the shielding effectiveness is kept above 70 dB in the range of 30~1 000 MHz, and it shows better extrusion processability. [ABSTRACT FROM AUTHOR]

In this work a broadband Magnetoelectric (ME) dipole antenna for the Global Navigation Satellite System (GNSS) applied to nanosatellites is proposed. The antenna consists of a reflective cavity with open walls containing four gaps to enhance the axial ratio (AR) bandwidth. Additionally, it includes two ME dipoles formed by two pairs of vertical and horizontal copper plates, one of which is trapezoidal and a T-Γ-shaped cross-feeding structure. A prototype was designed and subsequently manufactured and measured. The experimentally obtained results exhibit consistent agreement with simulated outcomes, demonstrating that the antenna has a wide impedance bandwidth of 111.36% from 1.13 GHz to 1.62 GHz for the Voltage Standing Wave Ratio (VSWR) ≤ 2 and a 3 dB AR bandwidth of 120.45% from 1.10 GHz to 1.63 GHz. Within this range, high gain (≥8.5 dBi) and high radiation efficiency (90%) can be achieved. Furthermore, the antenna exhibits right-hand circular polarization (RHCP) and possesses good unidirectional radiation characteristics with a high front-to-back ratio (≥ 20 dB). [ABSTRACT FROM AUTHOR]

In this work, an Insulated Metal Substrate (IMS) for packaging high-power electronic devices was created using hexagonal Boron Nitride (h-BN) mixture-based Thermally Conductive Adhesive (TCA) and copper plate with a matte side. Mechanical exfoliation of micron-scale BN particles results in a BN mixture containing h-BN nanosheets, micron particles, and nanoparticles. TCA was synthesized by dispersing a 40 % BN mixture modified by γ-aminopropyltriethoxysilane (KH550) into epoxy resin. The TCA has a relatively high thermal conductivity of 4.48 W·m-1·K-1 and a breakdown strength of 15.32 kV·mm-1. As the TCA film was coated on the matte side of the copper plate, the peel strength can reach 1.63 N·mm-1, indicating excellent practicality in the field of electronic packaging. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive description of preserved copper plates used for map printing in order to enrich the existing knowledge and, at the same time, contribute with new knowledge on the topic of the engraving of old maps. The dimensions, thickness, and weight of individual printing plates were measured. Qualitative indicators of the material were also examined. Printing plates originating from countries north of the Alps (former Czech lands) and from Mediterranean regions (Malta and Italy) are represented. For the purpose of the study, the term printing plate refers to a copperplate on which the engraving was made using the burin or line etching technique. These are some of the oldest reproduction techniques used for printing old maps. The period studied covers the 18th century, approximately. Studies dealing with a large set of printing plates and their classification are rather an exception (Hameleers 1989). The issue of the qualitative properties of printing plates has not yet been comprehensively addressed in the literature focusing on the history of cartography. [ABSTRACT FROM AUTHOR]

This article presents a novel bonding method for chip packaging applications in the semiconductor industry, with a focus on downsizing high-density and 3D-stacked interconnections to improve efficiency and performance. Microfluidic electroless interconnections have been identified as a potential solution for bonding pillar joints at low temperatures and pressures. However, the complex and time-consuming nature of their production process hinders their suitability for mass production. To overcome these challenges, we propose a tailored plating solution using an enhanced copper concentration and plating rate. By eliminating the need for fluid motion and reducing the process time, this method can be used for mass production. The Taguchi approach is first used to optimize the copper–quadrol complex solution with the plating rate and decomposition time. This solution exhibits a copper concentration that is over five times higher than that of conventional solutions, a plating rate of 22.2 μm/h, and a decomposition time of 8 min on a Cu layer substrate. This technique enables Cu pillars to be successfully bonded within 7 min at 35 °C. Planarizing the pillar surface yields a high bonding percentage of 99%. Mechanical shear testing shows a significant fracture strength of 76 MPa. [ABSTRACT FROM AUTHOR]

In this article, the process of fabrication of 24mm thick Copper welded and fully machined part of 2500 MW Turbo-generator is discussed. The challenge faced to make Copper Parts for turbo-generator through welding and the ways to overcome them are briefed, discussed. The challenge faced to make this large size turbo-generator through welding and the ways to overcome them are briefed. [ABSTRACT FROM AUTHOR]

Based on the current rapid development of electronic products, the development of light-weight, processable, environmentally friendly, long-life, durable, less corrosive, and tunable conductive composite materials with multiple applications may be the development direction of next-generation electronic devices. In this work, for the first time, we employed 3-Mercaptopropyltrimethoxysilane (3-MT) to modify viscose nonwovens and enhance the copper plating process. The prepared samples were characterized by Fourier transform infrared, Wide-angle X-ray diffraction (WAXD), scanning electron microscope + energy dispersive X-ray spectroscopy (SEM + EDS), thermogravimetric analysis (TGA), electrical resistivity, anti-corrosion, Joule heating, and electromagnetic interference (EMI) shielding. Results showed that 3-MT was covalently bound to the viscose surface through hydrolysis and condensation reactions and introduced SH groups. WAXD confirmed that the thiol modification did not change the internal crystal structure of viscose and copper ions. TGA and surface morphology analysis confirmed that the modified viscose promoted the deposition of metal particles in the copper plating process due to the affinity of thiol to metal so that copper particles almost completely wrapped the viscose fibers. In addition, 3MT@Cu@Viscose exhibits extremely low surface and volume resistivity (346.6 and 333.2 mΩ·m), improved corrosion resistance (corrosion rate reduced by 58% compared to the unmodified sample), fast Joule heating response (within 10 s) in low voltage (1 V) and excellent EMI shielding effectiveness (EMI SE > 50 dB). It showed great potential in future multi-functional electronic products such as electric heating sensors, smart clothing, and EMI shielding barrier. [ABSTRACT FROM AUTHOR]

Phase‐change thermal diodes with asymmetric and adjustable heat transfer capacity exhibit great application prospects in spacecraft heat management and solar energy storage. Current heat modulation strategies mainly depend on the anisotropic assistance from gravity and the rectification ratio can hardly be adjusted due to the immobilized inner structures. Here, a novel bioinspired thermal diode vapor chamber has been carried out with magnetic microgroove cones array sealed between two copper plates, where the evaporating plate with porous copper foam can reserve water and the condensing plate with patterned wettability can coagulate vapor into droplets at designated spot. With microgroove cones rooting from the evaporating plate and their tips contacting the condensing plate, these cones can directionally and rapidly transport condensed liquid from the condensing plate to evaporating plate under the unbalanced strong capillarity while prohibiting water flowing backward. This eventually leads to unidirectional liquid‐vapor circulation and anti‐gravitational directional heat transferring with a rectification ratio as high as 7.4. Such flowing of liquid can also be regulated by magnetically controlling the bending of cones to realize switched ON–OFF of thermal diode and achieve further modulation of heat management. This bioinspired thermal diode vapor chamber provides new ideas for intelligent thermal management systems. [ABSTRACT FROM AUTHOR]

Higher-order topological insulators exhibit intriguing capacity to confine energy on lower-dimensional boundaries owing to the unique bulk-boundary correspondence. Many potential practical applications of the higher-order states in classical wave systems have been proposed and achieved. In this work, we implement a second-order topological insulator in a waterborne acoustic crystal by drilling and grooving a copper plate based on a two-dimensional Su–Schrieffer–Heeger lattice with different intracell and intercell couplings. The far-field transmission spectrum and near-field pressure field distributions verify the existence of the one-dimensional edge states and zero-dimensional corner states in the bulk bandgap. Due to the highly localized edge and corner states, the polystyrene particles are trapped at the edges and corners by the acoustic gradient force. Our findings provide a good platform to manipulate underwater acoustic wave and may inspire topological acoustic applications. [ABSTRACT FROM AUTHOR]

Among the various reinforcement phases available in Cu-based composites, the unique layered structure and easy diffusion of A-layer atoms make MAX phases more suitable for reinforcing a copper matrix than others. In this study, Cu-coated Ti3AlC2 particles (Cu@Ti3AlC2) were prepared through electroless plating, and Cu@Ti3AlC2/Cu composites were fabricated via vacuum hot-press sintering. The phase composition and microstructure of both Cu@Ti3AlC2 powder and composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrate the creation of successful electroless copper plating to obtain a Cu coating on Ti3AlC2 particles. At 850 °C, a small amount of Ti3AlC2 particles decompose to form TiCx, while Al atoms from the A layer of MAX phase diffuse into the Cu matrix to form a solid solution with Cu(Al). The test results reveal that the density of the Cu@Ti3AlC2/Cu composite reaches 98.5%, with a maximum compressive strength of 705 MPa, which is 8.29% higher than that of the Ti3AlC2/Cu composite. Additionally, the compressive strain reaches 37.6%, representing an increase of 12.24% compared to that exhibited by the Ti3AlC2/Cu composite. [ABSTRACT FROM AUTHOR]

Currently, there is a shortage of potable water in several regions. Various alternative methods exist for producing purified water; however, one particular technology known as solar desalination is gaining prominence as a sustainable and environmentally friendly solution. Solar desalination harnesses solar energy to produce fresh water in regions with abundant sunlight. This study involved the fabrication of a nanostructured porous material composed of copper using anodization, followed by copper electroplating. In order to create three distinct nanoporous structures, we utilized three anodization periods of 40 min, 60 min, and 80 min. Subsequently, these structures underwent a copper deposition process for 30 min using the copper electroplating technique. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX), and X-ray diffraction (XRD) techniques were utilized to analyze the characteristics of the copper-plated nanoporous structure. Three distinct samples were utilized in solar desalination experiments, employing solar stills over a span of three consecutive days, with each sample being tested on a separate day. All three samples underwent desalination, unlike the standard solar still, which did not include any sample. Our observation revealed that the sample, which underwent 60 min of anodization followed by copper electroplating, had a significantly greater evaporation rate of 22.22% compared to the conventional still. [ABSTRACT FROM AUTHOR]

In the processing technology of printed circuit boards, the common electroless copper plating technology of ethylenediaminetetraacetic acid disodium (EDTA-2Na) has the problems of large surface stress, uneven crystal particles, and large surface roughness of the copper plating layer. To remedy the above shortcomings and meet the current requirements for copper interconnects in printed circuit boards (PCBs), the present study has investigated a chemical copper plating system that combines a high deposition rate with low stress. An electroless copper plating was then performed on a polyacrylonitrile-butadiene-styrene (ABS) plastic resin plate with 2,6-diaminopyridine (2,6-DAP), 2,2-bipyridine, sodium hydroxyethyl sulfonate (SHES) and NiSO4·6H2O as supplementary additives. By using scanning electron microscopy (SEM), electrochemical, atomic force microscopy (AFM), and X-ray diffraction (XRD) analyses, it has been shown that the average surface roughness Ra became reduced from 202 nm to 76.1 nm when using additives in the chemical copper plating process. Also, the internal stresses of the deposited copper layer on the (220) and (311) planes of a crystalline copper layer decreased from − 70.48 and − 53.03 to − 27.31 and − 27.16 MPa, respectively. The composite additive improved the quality of the copper layer of the EDTA-2Na-based chemical copper plating system, increasing the practical range of industrial applications and facilitating the subsequent application of higher-precision processing. [ABSTRACT FROM AUTHOR]

Wearable electronics, particularly electronic textiles, hold promise for significant advancements, yet their limited electrical conductivity hinders widespread application. This study examines the application of copper electrodeposition to enhance the electromechanical attributes of textronics. The conductive fabric undergoes copper electroplating for varying durations, assessing the increase in electrical conductivity relative to copper thickness. Experimental conditions span current densities from 0.2 to 20 A dm−2. Additionally, the research evaluates the mechanical resistance of the resulting interconnection with conventional electronic components. Voltammetric measurements, sheet resistance, and microscope observations establish optimal copper deposition conditions. As hypothesized, an inverse proportionality between the sheet resistance of the electrodeposited fabric and the thickness of the copper layer has been observed. This improvement raises a query: does the electromechanical reliability of e‐textiles improve with the addition of only a few micrometers of copper? The study reveals the significant enhancement of the mechanical resistance of soldered interconnections with rigid components after a few seconds of electrodeposition as well as an improvement of the quality factor of a textile antenna. In conclusion, electroplating significantly improves the electromechanical properties of textronics without compromising their wearability. This discovery paves the way for novel applications such as wireless fast charging with textile antennas. [ABSTRACT FROM AUTHOR]

The paper presents the investigation of the biological properties of Poly(Lactide)—Copper composite material obtained by sputter deposition of copper onto Poly(lactide) melt-blown nonwoven fabrics. The functionalized composite material was subjected to microbial activity tests against colonies of Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria, Chaetomium globosum and Candida albicans fungal mold species and biochemical–hematological tests including the evaluation of the Activated Partial Thromboplastin Time, Prothrombin Time, Thrombin Time and electron microscopy fibrin network imaging. The substantial antimicrobial and antifungal activities of the Poly(Lactide)–Copper composite suggests potential applications as an antibacterial/antifungal material. The unmodified Poly(Lactide) fabric showed accelerated human blood plasma clotting in the intrinsic pathway, while copper plating abolished this effect. Unmodified PLA itself could be used for the preparation of wound dressing materials, accelerating coagulation in the case of hemorrhages, and its modifications with the use of various metals might be applied as new customized materials where blood coagulation process could be well controlled, yielding additional anti-pathogen effects. [ABSTRACT FROM AUTHOR]