Fabrication Of Tapes Research Articles

Investigation of the energizing characteristics of a metal-insulation iron-based superconducting coil

With the progress of iron-based superconducting wire and tape fabrication technologies, extensive research has been conducted on iron-based superconducting coils. A deep understanding of the energizing characteristics of these coils is crucial for their large-scale application. This study investigates two metal-insulated double pancake coils, each having a different number of turns and co-wound with Ba0.6K0.4Fe2As2 iron-based superconducting tape and stainless-steel tape. We conducted critical current tests, sudden-discharge experiments, and charge-discharge cycles at 4.2 K to obtain the time constants and characteristic resistances of the coils. Additionally, the impact of stainless-steel as co-wound material on coil performance was analyzed. Theoretical models were employed to calculate the charging processes and validate them against experimental results. This research offers valuable insights for the practical application of iron-based superconducting materials.

Influence of drying conditions and plasticizer‐to‐binder ratio on the water‐based tape casting of La0.6Sr0.4Co0.2Fe0.8O3−δ

AbstractTape casting is a flexible technique for manufacturing scalable ceramic sheets. This study fabricated La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF6428) tapes using water‐based tape casting. A high molecular weight plasticizer, polyethylene glycol 4000, was chosen to balance flexibility and mechanical strength. Adjusting the plasticizer‐to‐binder ratio (R‐value) and increasing relative humidity during drying led to crack‐free and flawless green tapes of 330 µm. The uniform polymer matrix improved homogeneity and consistency as well. An applicable suspension formulation was developed for the water‐based fabrication of LSCF tapes for continuous production.

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Recently, the joining of rare-earth barium copper oxide coated conductor (CC) tapes using ultrasonic welding (UW) has demonstrated outstanding potential in the in-line fabrication of longer tapes required for superconducting device applications. The UW method can produce CC joints by applying ultrasonic vibration in less than one second, and hybrid welding (HW) has been adopted to improve further the joint resistance (R j) and electromechanical properties of the UW CC joints. However, conventional methods for preparing the HW and soldered CC joints involve applying solder flux to remove the oxide film, which can cause corrosion to the surface of the CC tapes and affect the joint’s lifespan during device operation. Therefore, this study aims to fabricate a robust HW CC joint of pre-solder insertion without solder flux and compare its joint strength and electromechanical properties with the traditional cases with the solder flux. While similar R j can be obtained from both cases of HW CC joints, the flux-free HW CC joint has slightly higher joint strength and superior adhesive characteristics than those with flux. The difference in fracture mechanisms after lap-shear and T-peel tests between flux-free HW and with flux was extensively discussed. Additionally, the study investigates the correlation between a decrease in R j with longer joint length in differently stabilized and processed CC tapes for flux-free HW. Overall, this study demonstrated that the flux-free HW method could efficiently produce robust CC joints with a lesser risk of corrosion and enhanced joint characteristics.

Kinetics mechanism on the efficiency of C substituting B in the MgB2 tape fabrication

Effective carbon doping is essential for MgB2 superconductors due to its enhancement on in-field critical current density. However, C-doped MgB2 samples prepared with different boron powders exhibit varying levels of C substitution efficiency, which directly affect the superconducting properties. In this article, to further investigate the factors influencing C substitution efficiency, a two-stage carbon doping process was established based on the in-situ X-ray diffraction (XRD) measurement. The process begins with the initial in-situ ternary reaction of Mg, B and C, followed by the subsequent diffusion of C into the MgB2 lattice. Through the analysis of thermodynamic equations, it can be inferred that the key factor in improving the C substitution efficiency for MgB2 is to align the activity of the B and C precursor powders, which enables a greater participation of carbon in the initial stage of the ternary reaction. According to the systematic study on nano-C doped MgB2 tapes, the C substitution efficiency in MgB2 tapes prepared using nano amorphous boron powder is notably lower compared to those prepared using micron crystalline boron powder. These findings suggest that high-activity amorphous B powder necessitates a C dopant with a lower activation energy to enhance its C substitution efficiency.

Facile fabrication of flexible and adhesive micro-supercapacitor tapes from conducting polymer solution for self-powered wearable sensing system

Flexible micro-supercapacitor (MSC) with in-plane electrodes has attracted significant attention as microscale energy storage device. Especially, flexible MSCs with adhesion properties are of great interest for wearable electronics. Here, we demonstrate a facile and cost-effective mask-assisted drop-casting method to fabricate adhesive MSC on medical tape using dimethyl sulfoxide (DMSO) doped poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) aqueous solution. The fabricated MSC with poly (vinyl alcohol)/H3PO4 gel electrolyte exhibits an areal specific capacitance of 10.96 mF cm−2 at a current density of 0.1 mA cm−2 with excellent mechanical flexibility. The MSC can be attached on various substrates due to the stickiness of the medical tape. For practical application, the MSC can be coupled with a solar cell to achieve a stand-alone power supply system for a flex senor in monitoring finger movements. Therefore, we believe that the mask-assisted drop-casting method paves a new way to develop flexible and adhesive MSCs for self-powered integrated wearable electronics.

Mussel-inspired hydrogels for fast fabrication of flexible SERS tape for point-of-care testing of β-blockers

The flexible surface-enhanced Raman scattering (SERS) platform has ceaselessly propelled the development of point-of-care testing (POCT) in diverse fields. Herein, we report a facile strategy for the SERS-chemometric analysis of four β-blockers (bisoprolol, metoprolol, acebutolol and esmolol) based on a super-sticky mussel-inspired hydrogel SERS tape. The surface morphology and mechanical properties of the hydrogel tape can be easily controlled by adjusting the compositional ratio. The optimized tape with excellent toughness and adhesiveness allows efficient collection of analytes through a simple "paste and peel off" approach, further by spraying with silver nanoparticles using a household sprayer to instantly assemble a flexible SERS substrate, the analytes can then detected by a portable Raman spectrometer. This POCT strategy enables the identification and discrimination of four similar β-blockers with high sensitivity and accuracy in combination with the statistical algorithms. The developed SERS tape is finally utilized for the recognition of β-blockers in simulated urine solution, which realizes a limit of detection of 1.0 ng mL-1, revealing a promising potential of this SERS-based POCT for the clinical detection of doping abuse.

Fabrication and Characterization of (Ba,Na)Fe2As2 Wires and Tapes

In order to enhance J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> in (Ba,Na)Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires and tapes further by improving texturing, we examined the following approaches; (1) Ag-sheathed HIP tapes, (2) AgSn-sheathed cold-pressed tapes, and (3) multifilamentary HIP wires with each filament having tape-like cross section. In addition, we attempted to increase I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> by fabricating (Ba,Na)Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> As <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> wires with larger core areas, and constructed a small demo coil using one of these wires with length up to 9 m. J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> characteristics of these new wires and the performance of the demo coil with and without an electrical insulation are reported.

Visualization of the grain structure in high-performance Ba1−x K x Fe2As2 superconducting tapes

122 type iron-based superconductors (IBSs) are potential for high-field applications, and the fabrication of high-performance IBS wires and tapes is essential. By using the powder-in-tube method, transport critical current density (J c) of hot-pressed (HP) silver-sheathed Ba1−x K x Fe2As2 (Ba-122) tapes have reached 1.5 × 105 A cm−2 at 4.2 K and 10 T. However, the J c of flat-rolled (FR) tapes is 6.2 × 104 A cm−2 (4.2 K, 10 T), less than half of the former. The grain orientation, grain size, and grain shape are important parameters for the understanding of the superconducting properties of IBS tapes. Such grain structure data can be provided by the electron backscatter diffraction (EBSD) technique. In this work, we extensively adopted EBSD to visualize the microstructure of state-of-the-art HP and FR Ba-122 tapes. The grain orientation, grain connectivity, grain size, and grain shape aspect ratio of these two types of tapes are quantitatively analyzed. The c-axis texture is commonly found in both HP and FR tapes, but no in-plane texture is discovered. The texture and grain connectivity in HP tapes are better than that in FR tapes. The grain size of FR tapes is smaller than that of HP tapes, and the hot-pressing processes can promote the growth of grains along the ab plane. We recommend that strong texture will promote the growth of grains, while the small-sized grains will return to limit the formation of texture. Therefore, finding a balance point that plays a synergistic promote effect of grain orientation and grain size is a strategy to improve the transport properties of IBS tapes further. The present results demonstrate that there is still margined to enhance the properties of IBS tapes.

Transport Coefficients in Y-Ba-Cu-O System for Ionized Jet Deposition Method

Ionized jet deposition (IJD) is a Physical Vapor Deposition (PVD) deposition technique suitable for the deposition of a wide range of materials on various solid substrates. Some of the main benefits of IJD are flexibility and a high number of deposition parameters such as pulse frequency, the distance between target and substrate, or acceleration voltage. These attributes provide the option to set the deposition according to the precise needs of any material. This deposition method has the potential for cost-effective scale-up and makes it viable for High-Temperature Superconductors (HTS) tapes fabrication. HTS tapes are very sensitive to chemical composition, therefore, it is necessary to partially adjust the input stoichiometry of the target in order to achieve the desired stoichiometry of the prepared film. This study is aimed at the influence of target stoichiometry on the chemical composition of prepared YBCO thin films. In this work, all deposition parameters were fixed except for the target stoichiometry. The substrate temperature was set to 650 °C, the oxygen was used as working gas and the deposition frequency was set to 15 Hz. The samples and targets were analysed by scanning electron microscopy and energy dispersive spectroscopy. In total 7 different stoichiometries are examined. The target stoichiometry ranges from Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.5</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> to Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4.5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> . The transport coefficients are calculated for this set of experimental conditions based on the observed data.

Numerical Study on Mechanical Properties of Conductors on Round Core Cables

The unique structure of conductors on round core (CORC) cable leads to symmetrical electromagnetic properties and excellent mechanical performance. However, it is quite a big challenge to analyze the mechanical properties of CORC cables, due to the unpredictable initial residual stress generated during the fabrication process of both tape and cable. In this paper, the mechanical model of CORC cable consists of several individual models representing the tape fabrication, cable fabrication, CORC cable bending and cooling process. The numerical model is verified by experimental results of both superconducting tapes and CORC cables. On basis of this, the numerical model is used to explain the mechanism of performance degradation during bending process. Moreover, the effects of winding angle on critical bending diameter are analyzed from the aspect of critical current degradation and physical extrusion. And simulation results are used to determine the principle critical bending diameter of CORC cable. Conclusions in this paper can be useful for design of CORC cables in applications where small bending diameter is needed.

Effect of Target Density on the Surface Morphology of Y-Ba-Cu-O Thin Films Prepared by Ionized Jet Deposition

Ionized jet deposition (IJD) is a pulse electron deposition method. It can be used for the preparation of thin films from a wide spectrum of materials on different substrates. The main benefits of IJD are high flexibility and a possibility to change many of the deposition parameters. Some of them even during the deposition such as acceleration voltage, working gas, substrate temperature, etc. The wide variability of the deposition parameters allows finding the ideal conditions for the preparation of thin films of almost any material. This deposition method has a great potential for a cost-effective scale-up of HTS (High-temperature Superconductors) tapes fabrication. This research is focused on the study of the influence of target density on the microstructure of the deposited YBCO thin layers. The target density has an important role in the morphology of thin films. In this work, the deposition parameters were fixed (except for target density). The distance between substrate and target was 110 mm and substrate temperatures were set to 650 °C. The targets and samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and LED Confocal profilometer. Nine different YBCO targets with densities from 3.8 g·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> to 5.6 g·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> were prepared in total. All targets were prepared from a single batch of precursor powder at ambient atmosphere and different sintering temperatures and times.

Facile fabrication of low-cost and scalable graphite tape as novel current collectors for flexible supercapacitors

Flexible supercapacitors are regarded as a good candidate for powering flexible and wearable electronics. Currently, flexible current collectors for supercapacitors are still limited. Carbon-based materials with high conductivity and good flexibility are excellent current collectors for supercapacitors. However, the synthesis process for carbon-based current collectors is very tedious and time-consuming, leading to high synthesis cost. Here, graphite tape composite based current collectors with high electric conductivity and flexibility have been developed by simply peeling off a thin graphite layer with a tape from a low-cost graphite sheet. The graphite tape can be easily scaled up, has an electric conductivity of 1395 S/m, and maintains stable conductivity during different bending states. The optimized MnO2@graphite tape electrode shows a maximum specific capacitance of 577.5 mF/cm2 at 0.5 mA/cm2. The supercapacitor based on the optimized electrode delivers a high specific capacitance of 189.3 mF/cm2 and excellent flexibility during different bending states and 2000 bending cycles. The high performance of electrodes and supercapacitors is related to the excellent conductivity and good mechanical flexibility of the graphite tape. This work opens up a facile fabrication method for low-cost, scalable, and high-performance carbon-based current collectors for flexible supercapacitors.

Application of composite binders in the fabrication of LTCC green tape based on the borosilicate glass/Al2O3 system with optimized Ca/Mg ratios

This study aimed at developing a high-performance low temperature co-fired ceramic (LTCC) green tape with good sintering characteristics and dielectric properties based on a borosilicate glass/Al2O3 system. First, the Ca/Mg ratio in the glass composition was optimized to modify the microstructure, sintering density, and dielectric properties. Subsequently, composite binders of various molecular weights were employed in the tape casting slurries, to improve the performance of the green tapes. Following a comprehensive analysis of the multiple necessary performance parameters, we concluded that the glass/Al2O3 composite with Ca/Mg = 4.30 sintered at 875 °C presented a dense microstructure with outstanding sintering characteristics and dielectric properties (density of 3.14 g/cm3, permittivity of 8.02 and dielectric loss of 11 × 10−4 (10 MHz)). The application of composite binders with 60% B20H and 40% B79 yielded a green tape with a high density (1.94 g/cm3), smooth surface (Ra = 213 nm), and good workability. In addition, the thermal and mechanical properties of the optimized composite were practical for electronic packaging applications. This positive assessment of the co-firing compatibility between the composite and Ag electrodes augments its application potential for LTCC technology.

The cross-sectional curvature effect of twisted tapes on heat transfer performance

This study reports the cross-sectional curvature effect resulted from a twisted tape fabrication or installation into an annular pipe on the enhancement of heat transfer to pay attention to the use of twisted tapes more efficiently. Six different twisted tapes having two twist ratios (3 and 4) and three curve ratios (1.761, 2.252 and 3.271) in the Reynolds number range from 5840 to 30,900 were numerically analyzed. The analysis method was validated with three different experimental results from loose-fit to tight-fit of a twisted tape. According to polyhedral mesh element analysis of curved cross-sectional twisted tapes, capable of having better compatibility with experimental results, Nusselt numbers increased with increasing curve ratio and decreasing Reynolds number and twist ratio. While the curved twisted tape is more efficient than the smooth tube, losses on heat transfer efficiency are observed compared to the classical twisted tape. Although the losses caused by the curvature on the twisted tape appear to be insignificant at high curve ratios, the effect of low curve ratios increases significantly. For the lowest CR and the highest TR under analysis conditions, it was observed that TT lost 28 % of its normal productivity increase due to this effect.

Fabrication of Bi-2223 High Temperature Superconducting Tapes With Groove Rolling Process

Bi 1.76 Pb 0.34 Sr 1.93 Ca 2.02 Cu 3.06 O 10+δ (Bi-2223) high temperature superconducting tapes were fabricated with Powder in tube (PIT) process. The traditional drawing process was partially replaced by groove rolling. The influence of cold working method on the filament density, the phase evolution mechanism as well as superconducting properties has been systematically studied. The groove rolling process could obviously enhance the filament density of Bi-2223 green wires, which thus led to the change of Bi-2223 formation rate. Meanwhile, although the heat treatment process has not been thoroughly optimized, the residual secondary phase content was still high, the critical current has been improved for more than 20% with groove rolling process, which should be attributed to the improved intergrain connections. On the other hand, the groove rolling process was also effective on the fabrication of Bi-2223 tapes with larger filament number, such as 85 or 121 to maintain the uniformity of filament deformation.

Silver Tape

We propose Silver Tape, a simple yet novel fabrication technique to transfer inkjet-printed silver traces from paper onto versatile substrates, without time-/space- consuming processes such as screen printing or heat sintering. This allows users to quickly implement silver traces with a variety of properties by exploiting a wide range of substrates. For instance, high flexibility can be achieved with Scotch tape, high transparency with polydimethylsiloxane (PDMS), heat durability with Kapton polyimide tape, water solubility with 3M water-soluble tape, and beyond. Many of these properties are not achievable with conventional substrates that are used for inkjet-printing conductive traces. Specifically, our technique leverages the commonly undesired low adhesion property of the inkjet printing films and repurposes these films as temporary transfer media. We describe our fabrication methods with a library of materials we can utilize, evaluate the mechanical and electrical properties of the transferred traces, and conclude with several demonstrative applications. We believe Silver Tape enriches novel interactions for the ubiquitous computing domain, by enabling digital fabrication of electronics on versatile materials, surfaces, and shapes.

Strong cube texture of super-high tungsten Ni–W alloy substrates used in REBCO coated conductors

Biaxially textured super-high tungsten Ni–W alloy substrates have been fabricated through the composite substrate method in view of coated conductor applications. The tungsten content exceeds 10% in the obtained substrates. The excellent super-high tungsten substrate (Ni10W) had a strong cube texture consistent with commercial Ni5W and better than Ni8W or Ni9W substrate. Furthermore, yield strength ∼310 MPa (twice of Ni5W) and saturation magnetization of only 4% to that of Ni5W at the temperature of 77 K was calculated for Ni10W substrate. The novel Ni10W substrate with strong cube texture and negligible magnetization is best suited to be utilized for 2nd generation coated conductor REBCO. It can significantly improve the progress of using the RABiTS route in the fabrication of REBCO tapes. Meantime, the mechanisms of the cube evolution and elements diffusion in super high tungsten substrate are also studied.

Highly c-axis orientated superconducting core and large critical current density in Ba0.6Na0.4Fe2As2 powder-in-tube tape

Improvement of the critical current density (Jc) of superconducting wires/tapes is one of the key issues in the field of superconductivity applications. Here we report the fabrication of a silver-sheathed Ba1−xNaxFe2As2 (BaNa-122) superconducting tape by using a powder-in-tube technique and its superconducting properties, in particular transport Jc, as well as the tape-core texture. The optimally-doped BaNa-122 tape with Na concentration x = 0.4 exhibits the superconducting critical temperature (Tc) of 33.7 K and high transport Jc of 4 × 104 A/cm2 at 4.2 K in a magnetic field of 4 T. Patterns of x-ray diffraction for the superconducting core show that the degree of c-axis orientation is significantly enhanced through the tape fabrication process. The tendency of c-axis orientation is advantageous for achieving higher Jc, suggesting the high potential of BaNa-122 for superconducting wire/tape applications.

High-Speed Deposition of High-Performance REBCO Films by Using a Radiation Assisted Conductive Heating PLD System

To increase the throughput and to further improve the performance of REBa2Cu3O7 (REBCO) superconductors are two important aspects for deposition of REBCO by pulsed laser deposition (PLD) routes. In this paper, we developed a radiation-assisted conductive heating (RACH) technique, in order to obtain homogeneous temperature on the tape surface when passing the deposition zone at dynamic PLD process. Three series of high-performance REBCO productions: GdBCO, (Y,Gd)BCO, and EuBCO+BHO have been fabricated for power and magnet applications. High J c of 3 MA/cm2 at 77 K self-field was achieved at film thickness over 2 μ m and excellent I c homogeneity along the length was achieved for over 300 m long tape. Compared with traditional conductive heating mode, in-field I c performances were increased by over 50% at 30 and 4.2 K on the REBCO tape with optimized composition by using the RACH PLD system. Moreover, high tape travelling speed of over 100 m/h was used for all the REBCO deposition process, which provides possibility of up-scaling the techniques for meeting requirements of the mass production. Improvements of superconductivity performance demonstrate that the RACH technique is a high-efficient and stable approach for long-length REBCO tape fabrication.

Effects of different directional rolling on the fabrication of 7-filament Ba1-xKxFe2As2 tapes

The transport performance of iron-based superconductor has been raised rapidly for the past few years, and the critical current density of single-core tape has surpassed 1.5 × 105 A/cm2 at 4.2 K and 10 T. In this work, 7-filament Ba1-xKxFe2As2/Ag tapes were prepared by adopting the conventional power-in-tube method. Unidirectional and bidirectional rolling experiments were designed to investigate the effect of rolling direction on the tapes. It is found that unidirectional rolling will easily break the superconducting filaments; while the bidirectional rolling can achieve the integrity and uniformity of each superconducting filament with tape thinning. Moreover, a critical current (Ic) of 157.5 A was obtained in bidirectional rolled 0.3 mm thick tape, which realized a 104 A/cm2 of engineering critical current density (Je) at 4.2 K and 10 T. In the long run, the bidirectional rolling method shows significant advantages in fabricating multi-filamentary and long tapes.