Structure Of Tapes Research Articles

Electromagnetic-thermal modeling of high-temperature superconducting coils with homogenized method and different formulations: a benchmark

Abstract High-temperature superconducting coils are used in various large-scale
applications, like rotating machines and high-field magnets. However, modeling
these coils is a complicated and time-consuming process, especially due to the non-
linearity of the current-voltage characteristics of the superconductors and the complex
multiphysics involved. In this work, we used a fast homogenized method to model
the coupled electromagnetic and electrothermal properties of racetrack and pancake
coils for different applications. For this purpose, various formulations wielding
homogenization methods are used and benchmarked with each other, as well as with
models considering the detailed structure of the HTS tapes. We observe a very good
agreement between different models (homogenized and detailed), and we discuss the
pros and cons of the inclusion of insulating layers between the turns in homogenization.
This work was performed under the collaboration of the COST action modeling teams
and can be used as a review of the state-of-the-art superconductor modeling techniques,
and a source for the development and benchmark of future numerical methods.

An asymmetric stabilizer layer structure of REBCO superconducting tapes for resistive superconducting fault current limiters

Used in resistive superconducting fault current limiters (R-SFCLs), REBCO tapes are required to have both large current limiting resistance and high over-current bearing capacity. The contradiction between high resistance and large over-current is the main difficulty in the design of REBCO-tape structure for R-SFCLs. In this paper, an asymmetric stabilizer layer structure of REBCO tapes has been proposed, fabricated and tested for R-SFCLs. Comparing to traditional tapes with a symmetric stabilizer structure, the REBCO tape with new structure showed a 59 % improvement in over-current bearing capacity: the peak current increased from 1020 A to 1620 A while keeping the same total resistance. Simulation calculation on the current distributions in every layer showed that the asymmetric structure is superior to the symmetric structure.

Numerical explorations of solvent borne adhesives: a lattice-based approach to morphology formation

The internal structure of adhesive tapes determines the effective mechanical properties. This holds true especially for blended systems, here consisting of acrylate and rubber phases. In this note, we propose a lattice-based model to study numerically the formation of internal morphologies within a four-component mixture (of discrete particles) where the solvent components evaporate. Mimicking numerically the interaction between rubber, acrylate, and two different types of solvents, relevant for the technology of adhesive tapes, we aim to obtain realistic distributions of rubber ball-shaped morphologies—they play a key role in the overall functionality of those special adhesives. Our model incorporates the evaporation of both solvents and allows for tuning the strength of two essentially different solvent–solute interactions and of the temperature of the system.

Structure of Dispersion-Reinforced Copper Substrate Tapes for 2G HTS

Structure of Dispersion-Reinforced Copper Substrate Tapes for 2G HTS

Microstructure and Properties of 20Cr23Ni18 (AISI 304L) Thin Steel Tapes Obtained by Melt Spinning

The paper presents the results of a study of morphology, chemical composition, microcrystalline structure and properties of thin tapes of alloy grade 20KH23N18S2, obtained by melt spinning. The influence of process parameters on the properties and microstructure of the tapes is established.

Structural Analysis of 2G HTS Tapes under Different Loading Conditions for HTS Power Cable using Finite Element Modeling

In High Temperature Superconducting (HTS) power cable, HTS tapes are wound helically around a circular former and are subjected to different types of mechanical loads during manufacturing, transportation and installation of cable. The strain developed within the HTS tape during these processes may affect the superconducting properties of the tape. In the present work, 3D structural finite element (FE) models using ANSYS® are developed to obtain the strain behaviour of the tape under different loading conditions, considering the layered sandwich composite structure of 2G HTS tapes. The analysis is carried out with axial tensile and twisting loads on the tape, during helical winding of tape around the former and a combined effect of helical winding with external tensile and bending loads. The result obtained from FE simulation due to applied tensile load is compared with the established experimental result, which shows a good agreement. Further, the strain developed within the tape affects the critical current. Therefore, the strain is coupled with an empirical relation to obtain the critical current degradation of the tape. The FE analysis is carried out for five different winding pitches and four different bending radii with YBCO layer in the downward position and the corresponding critical currents are estimated. Further, a minimum winding pitch is obtained, below which the rapid degradation of critical current is initiated. The results show that the HTS tape with YBCO in downward position can withstand more amount of external load without affecting the critical axial strain of the tape.

Sintering and final properties of kaolinite‐magnesite tapes for the manufacture of cordierite‐mullite ceramics

AbstractThe present work aims at studying the effect of the sintering temperature and magnesite addition on the structure and final properties of silicate ceramics tapes. A kaolinitic clay from Algeria was selected and mixed with different magnesite contents (≤12 mass%). Tape casting process was used to produce the green tapes in an aqueous system with optimized amount of surfactants. The green tapes were fired from 1000°C to 1200°C using a dwelling time of 30 minutes. The effect of the dwelling time was investigated for a firing temperature of 1200°C namely: 30 minutes, 1 hour 30 minutes and 3 hours for samples with 6 and 12 mass% of magnesite. Regarding firing conditions, crystalline phases, thermal conductivity, porosity, and flexural strength were analyzed. The results showed that increasing the sintering temperature to 1200°C tended to significantly decrease the total porosity of samples, which led to the improvement of the stress to rupture values. Specimens with 6 and 12 mass% sintered during 3 hours exhibited highest stress to rupture values (≈117 MPa) and lowest thermal conductivity (<0.2 W.m−1.K−1) and moderate open porosity (27%). The as‐obtained ceramics appeared promising for further utilization in refractory industry, thanks to the presence of both cordierite and mullite phases.

Theoretical analysis of heat transport in tilted stacks of HTS tapes at temperatures above 20 K

Tilted stacks of HTS tapes show favourable properties in terms of magnetisation. Magnetised stacks can be applied in superconducting rotating machines. In such case they will be subjected to varying magnetic fields and heat generation will occur. Therefore it is important to understand heat transfer in anisotropic structure of a stack to avoid overheating and optimise the shape for maximum magnetisation.To analyse the heat transfer a computational procedure to find components of anisotropic thermal conductivity is developed and compared with existing experimental data. The material parameters ready to use in other analyses are provided. Anisotropy of the structure of the HTS tapes plays crucial role in definition of the thermal behaviour of the investigated elements.The thermal behaviour of the stacks with different angles of tilt is investigated with a numerical model. Results show that the geometry of the stack significantly affects heat transfer. Analytical formulas describing the thermal behaviour of the stack depending on its dimensions are developed. The method to increase the speed of calculations by homogenising the stack is presented and its accuracy assessed.

The influence of the shock treatment under heating on the structure and properties of HTS tapes

The influence of shocks of different intensity on the structure and properties of multifilamentary superconducting tapes of Bi2Sr2Ca2Cu3O10+x (Bi-2223) and MgB2 compounds was studied. The Plasma Focus setup was used to produce the plasma shock waves, and a specially designed setup was utilized for the mechanical shock treatment. The experiments have shown a possibility to increase the critical current of MgB2 tapes by more than 60% in magnetic fields of 1.5-2.0 T due to the treatment. The critical current increase is caused by homogeneity improvement, densification of superconducting filaments and the pinning enhancement.

Textured tape substrates from binary copper alloys with vanadium and yttrium for the epitaxial deposition of buffer and superconducting layers

The structure of tapes of binary Cu–0.6 wt % V and Cu–1 wt % Y alloys and texturing process of them in the course of cold deformation by rolling to ~99% and subsequent recrystallizing annealing have been studied. The possibility of achieving the perfect cube texture in thin tapes made from binary copper-based alloys with vanadium and yttrium additions has in principle been shown. This opens the prospect of using them as substrates when manufacturing tapes of second-generation high-temperature superconductors. Optimum annealing conditions for the studied alloys have been determined, which have made it possible to produce the perfect biaxial texture with a content of cube {001}〈100〉 ± 10° grains on the surfaces of textured tapes of more than 95%.

Structural modeling of HTS tapes and cables

Structural finite element analysis (FEA) has been used as an insightful tool to investigate the electromechanical behavior of HTS REBCO tapes and twisted stacked-tape cables under tension, torsion, bending and combined loads. A novel technique was developed for modeling the layered composite structure of the 2G tapes with structural solid-shell elements in ANSYS®. The FEA models produced detailed strain information for the REBCO superconducting layer which was then paired with an analytical model to predict the critical current performance of the 2G HTS tapes under various loads. Two commercially available HTS tapes (SuperPower and SuNAM) under tension, torsion and combined tension–torsion were first analyzed with FEA and compared with available experimental results at 77K. A sharp critical current degradation was experienced at the yield strength of the tapes under tension and below a 100mm twist-pitch under torsion. Combined tension–torsion loads had a more gradual degradation of critical current for twist-pitches of 115mm or shorter but had a negligible difference compared to pure tension for longer twist-pitches. Using the structural solid-shell technique for modeling 2G tapes in ANSYS®, an FEA methodology for simulating full scale three-dimensional HTS stacked-tape cables under pure bending was created. A model of a Twisted-Stacked Tape Cable (TSTC), a configuration first proposed at MIT, was initially developed and then adapted to the slotted-core HTS Cable-In-Conduit Conductor produced by the ENEA laboratory in Italy. The numerical axial strain of the HTS REBCO tapes within the cables as calculated by FEA were found to agree with an analytical model for two cases: perfect-slip (frictionless) and no-slip (bonded). The ENEA CICC model was also compared with recent experimental critical current data at 77K and was found to match best using a low friction coefficient of 0.02 indicating that the tapes within the cable freely slide with respect to each other helping to reduce the axial strain during bending.

Effect of Small Addition of Cobalt on Magnetic Properties and Internal Stresses Sources in the Form of Free Volumes and Pseudo-Dislocation Dipoles in Fe78CoXSi11-XB11 (x = 0 Or 2) Alloys / Wpływ Nieznacznego Dodatku Kobaltu Na Właściwości Magnetyczne Oraz Źródła Naprężeń Wewnętrznych W Postaci Wolnych Objętości Oraz Pseudodyslokacyjnych Dipoli W Stopach Fe78CoXSi11-XB11 (x = 0 Or 2)

Amorphous materials in the form of tapes, despite being discovered more than half a century ago, are still the object of interest for materials engineers and electro-technical industry. They possess a great application potential, and are constantly studied for new variations. Due to the different structure from the commonly manufactured textured FeSi sheets, FeCoB based amorphous alloys demonstrate very good, so called soft magnetic properties. This paper presents the results of studying the structure and magnetic properties of tapes of Fe78CoxSi11-xB11(X = 0 or 2) alloys of amorphous structure. In addition, the effect of Co alloy addition on the type of structural defects in the area of ferromagnetic saturation approach was examined. It was found that a small addition of Co affects the increase of saturation magnetization value, as well as the distribution of magnetization vectors within the stresses sources in form of structure defects.

Influence of conditions of shock-wave effect of plasma on the structure and current-carrying capacity of multilayer high-temperature superconducting tapes

The article presents the results of the investigation of the influence of shock-wave effects on the structure and the critical currents of multilayer high-temperature superconductors—HTS tapes produced by the EAS-E HTS (VAC). Shock-wave exposure was carried out using an installation of a plasma focus (PF) type. It was experimentally found that an increase in the critical current by 20% or more was achieved in its own magnetic field and in external magnetic fields in the range of 0.5–2.5 T. The increase depended on the conditions of the shock-wave treatment (the distance from the plasma source (PF anode) and the number of shock wave pulses). In magnetic fields of more than 3 T, the effect of an increase in the critical current was not observed. Microstructural studies revealed both a compression and destruction of the individual layers of HTS in the strike zone depending on the conditions of the impact. The most severe degradation of the structure and the critical current was shown on the tape samples treated at distances of 25–30 mm from the PF anode. The critical current increased and exceeded the initial values of untreated tapes (75–85 A) at distances of 35–65 mm. The phase composition of HTS layers by XRD changed little after shock-wave treatment. Depending on the number of shock pulses and distance from the anode in the area of treatment, the tape’s thickness was reduced owing to compression or was increased owing to swelling of the tape.

The Structure of Cross‐β Tapes and Tubes Formed by an Octapeptide, αSβ1

The Structure of Cross‐β Tapes and Tubes Formed by an Octapeptide, αSβ1

Structure and morphology of linear polyethylene extrudates induced by elongational flow

AbstractThis study focuses on the structure, morphology, and properties of linear polyethylene (PE) profiles manufactured by continuous extrusion. High level of chain orientation was achieved using specific flow and processing conditions. An extrusion die with semihyperbolic convergency was used to generate high percentage of elongational flow and chain extension. Simultaneously, high extrusion pressure and relatively low melt temperature led to flow‐induced crystallization of PE extended chains. The structure of PE tapes consists of crystal aggregates with different level of orientation and crystallinity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A Structure Design of HTS Current Leads With Respect to the Structure of Coated Conductor and the Current Terminal

High temperature superconductor (HTS) is a promising material as current leads for large current applications, because it has zero resistance. However, a single HTS tape has limitation on the capacity of current rating due to the critical current of the HTS tape. Therefore, stacking or parallel structure of the HTS tapes is inevitable in high temperature superconducting current leads (HTSCLs) for large current application. In this paper, several stacking methods with respect to the shape of the current terminal and the structure of the HTS tape are studied and the characteristics of the stacked samples are investigated by experimental analysis. The critical currents of the HTS modules were measured and the conductive heat leakage of a stabilizer layer was calculated. From this analysis, the characteristics of the current distribution and decrease in the critical current of HTS modules with respect to the shape of the current terminal were obtained. Based on the results, the required stacking number of the HTS tapes for certain operating current HTSCLs can be calculated.

Metal Supported Solid Oxide Fuel Cell by Freeze Tape Casting

Freeze tape casting was used to fabricate a porous metal support for the solid oxide fuel cell (SOFC). The parameters that affect tape quality, such as casting temperature, solid loading, amount of additives and particle size of steel powders, have been investigated. It was found that that casting temperatures between -40°C and -80°C did not affect pore size and structure of the metallic tapes. The porosity and shrinkage rate of the metallic tapes is highly influenced by the solid loading, but not by the particle size of the steel powders. Multiple layers of the single cell structure were deposited on the freeze cast green tape by screen printing. A composite cathode of nano-size lanthanum strontium manganite (LSM) plus YSZ was obtained by infiltration.

Mechanische Aspekte von verschiedenen Polypropylenimplantaten in der Harninkontinenzchirurgie

PURPOSE: Suburethral tapes are widely used in urogynecology. Aim of the study was to evaluate the mechanical characteristics of frequently used implants for the treatment of urinary stress incontinence. MATERIAL AND METHODS: The static and dynamic characteristics of seven tapes used in urogynecology were compared with each other. Parameters included breaking strength, flexural stiffness, weight, pore size, porosity, distension, width of support with and without tension, thickness of the thread and capillary properties. RESULTS: The mechanical characteristics of the implants differ considerably. These differences were present with regard to both static and dynamic properties, and the differences are influenced by the quantity of filaments within the thread. In addition to the mono- or oligofilamentary, macroporous structure of the tapes there is a tendency in recent implants to a higher porosity and reduced distension. CONCLUSION: To date, the mechanical criteria for implants in urogynecology have not been extensively defined. Although all tested tapes consist of polypropylene, this study indicates a great variability with regard to individual mechanical characteristics.

Texture, structure and properties of Ni-based binary alloy tapes for HTS substrates

Abstract Depending on the contents of alloying elements (Nb, up to 5.4 at.%; W, up to 7.4 at.%; Re, up to 4.1 at.%; Mo, up to 9.5 at.%; V, up to 10.1 at.%; Mn, up to 22.1 at.%; Al, 12.0 at.%; and Cr, up to 22.0 at.%) texture, structure, and physical and mechanical properties are studied in thin tapes that serve as substrates for epitaxial deposition of a high-temperature superconductor on the nickel-based binary alloys. The upper limit of alloying element content is established at which sharp cube texture of primary recrystallization is feasible to be formed. It is shown that such boundary concentration of alloying elements is associated with a certain quantitative ratio between the deformation texture components and with a certain magnitude of the concentration expansion of lattice parameter. Some mechanical and physical properties of alloys with cube texture are determined.

Effect of Postdrawing Temperature on Structure, Morphology, and Mechanical Properties of Melt-Spun Isotactic Polypropylene Tapes

Structure, morphology, and mechanical properties of melt-spun and postdrawn isotactic polypropylene (iPP) tapes are analyzed to study the effect of postdraw temperature applied. For affine drawing conditions, i.e., no effective relaxation of the molecules occurs during postdrawing, the Young's modulus is uniquely determined by the applied draw ratio. Only above a certain postdrawing temperature, the tensile modulus starts to decrease, indicating the onset of a nonaffine deformation, i.e., the occurrence of effective molecular relaxation during postdrawing. However, the overall mechanical behavior strongly depends on the postdrawing temperature used. For fixed draw ratios, a significant drop in yield stress can be observed with decreasing drawing temperature. Structural and morphological characterization indicates that, beside affine and nonaffine drawing regimes, mainly formation of the mesomorphic phase during solid-state drawing yields to the different mechanical behavior.