Thin Tape Research Articles

Organic additives in gel-tape casting of ceramic powders – A novel approach to the problem of elasticity and cracking of thin tapes

Polymerization reactions are frequently used in fabrication of a wide range of ceramic components, from 3D elements (gelcasting, UV-curing), through thin tapes (gel-tape casting) to porous samples (mechanical foaming coupled with gelcasting). The analysis of the properties of organic additives used in these techniques as well as factors which influence the polymerization reaction in ceramic suspension are seldom described in the scientific literature. For this reason this paper presents the properties of selected monomers and polymers with influence on the elasticity of zirconia tapes obtained by gel-tape casting. The measured parameters were as follows: glass transition temperature of polymers with and without external plasticizers, wetting angle of ceramic substrates by monomers, and viscoelastic properties of zirconia slurries. The issues of oxygen inhibition, polymerization rate and polymerization shrinkage with influence on unwanted cracking of thin tapes are also discussed. The location of polymeric binder in green bodies was analyzed by SEM.

In 계 저융점합금의 닥터 블레이드 테이프캐스팅

Tape casting is an important forming operation used to prepare flat sheets in the various industries. In this study, Doctor Blade tape casting of In-based low melting point alloy was carried out. The purpose of this investigation was to determine the possibility of applying the Doctor Blade tape casting process to the manufacture of low melting point alloy sheets that can be used as thermal fusible parts of battery safety systems. In-based molten alloy that has a melting point of <TEX>$95^{\circ}C$</TEX> was produced; it's viscosity was measured at various temperatures. The molten alloy was used as a slip in the caster of the Doctor Blade tape casting system. The effects of the molten alloy temperatures and carrier speeds on the produced sheet shape were observed. For the casting conditions of 1.5 cm slip height, <TEX>$120^{\circ}C$</TEX> slip temperature, 0.05 mm blade gap and 60 m/min. carrier speed, an In-based alloy thin tape well shaped with 0.16 mm uniform thickness was continuously produced.

Adhesion of heterogeneous thin films II: Adhesive heterogeneity

This paper continues the study of the effective adhesion of thin films on rigid substrates in the presence of spatial heterogeneities started in Xia et al. (2013). In this paper, we focus on thin adhesive tape with spatial heterogeneity in the adhesive strength. This heterogeneity leads to a wavy peel front and consequently a complex corrugated shape in the tape. We develop a theory for the evolution of the peel front that accounts for this complex interaction, and an experimental method that is able to examine this in detail. We show through theory and experimentation that spatial patterning of the adhesive strength can lead to a very rich range of behaviors in the effective adhesive strength. In particular we show that adhesive heterogeneity can be used to create asymmetry in that the force required to peel the tape in one direction can be different from that in the other.

Strain Management in HTS High Current Cables

The best performing HTS conductors are available in the form of thin tapes with operating current in the range of 200 A at the operating conditions. To realize conductors with high current carrying capability, in the range of several tens of kA, a large number of tapes must be assembled in a cable. The conventional stranding methods for round conductors are not applicable to thin tapes. CRPP has developed an assembly concept based on twisted stacks of tapes soldered into a copper profile. The ability to withstand bending and torsion strain is the main issue for the design of a high current flat cable based on twisted stacks of HTS tapes. An analytical mechanical model was developed and validated with the results of measurements. Parametric analyses are used to select the optimum layout for the first full size prototype of the coming HTS conductor for fusion. Various configurations of the cable are presented and compared, paying attention in particular to the strain acting in the tape. The chosen set of cable parameters satisfies electromechanical limitations and provides feasibility of strand winding.

Quench Property of Twisted-Pair &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$\hbox{MgB}_{2}$&lt;/tex-math&gt;&lt;/inline-formula&gt; Superconducting Cables in Helium Gas

CERN's twisted-pair superconducting cable is a novel design which offers filament transposition, low cable inductance and is particularly suited for tape conductors such as 2G YBCO coated conductors, Ag-sheathed Bi2223 tapes and Ni/Monel-sheathed MgB 2 tapes. A typical design of such twistedpair cables consists of multiple superconducting tapes intercalated with thin copper tapes as additional stabilizers. The copper tapes are typically not soldered to the superconducting tapes so that sufficient flexibility is retained for the twisting of the tape assembly. The electrical and thermal contacts between the copper and superconducting tapes are an important parameter for current sharing, cryogenic stability and quench propagation. Using an MgB 2 twisted-pair cable assembly manufactured at CERN, we have carried out minimum quench energy (MQE) and propagation velocity (v p ) measurements with point-like heat deposition localized within a tape. Furthermore, different contacts between the copper and superconductor around the hot spot have also been studied, including the co-twisted assembly in Kapton wrapping and locally separated tapes. The measurements have been performed in cooling helium gas at temperatures between 20 K and 35 K, with different current fractions with respect to the thermal runaway current. The results suggest a potential optimization strategy, compromising between: a higher stabilization with better contact between the copper and superconducting layers; and a faster propagation velocity and easier quench detection with a higher contact resistance.

Formation of structure and crystallographic texture in Fe-50%Ni thin tapes under high magnetic field annealing

For the first time the influence of a high direct current (DC) magnetic field on the structure and texture formation in tapes of Ni48.8Fe51.2 alloy was investigated. Cube texture formation was studied in tapes after cold rolling to 98.8% and annealing in a high magnetic field up to 20T. Samples were subjected to magnetic annealing below and above the Curie point. Structure and texture were studied using electron backscatter diffraction (EBSD) technique, transmission electron microscopy, and magnetic hysteresis loops measurements. The experiments show a significant increase of the {001}±10° volume fraction in the recrystallization texture with the main orientation {100}〈001〉, when the magnetic annealing is carried out at a temperature below the Curie point.

Conditions of sharp cube texture formation in thin tapes of Cu-Ni alloys for second-generation high-temperature superconductors

We have studied the formation of sharp cube texture in Cu-Ni alloy tapes with nickel content 10, 20, 30, and 40 at %, manufactured by cold rolling to 98.6–99% and subsequent recrystallization annealing. Optimum regimes of annealing are determined for all these alloys, which allow a sharp cube texture with ∼95% cubic grains to be obtained.

Investigation of magnetic field manipulated electrons produced from laser-driven ultrafast x-ray sources using x-ray emission spectroscopy

We used x-ray emission spectroscopy to study energetic electrons (10–100 keV) generated at the laser focus of an intense ultrafast laser interacting with a primary thin film tape target. The electrons penetrated the tape and reached a secondary target of thin metal foils as the probe. The trajectories of these electrons were manipulated with an external magnetic field generated from a home-made Halbach magnet. The interaction of these energetic electrons with the probe produced characteristic x-rays, which were used to infer the flux and temperature of the electrons emitted from the laser focus at the primary tape target. A potential application using these energetic electrons is discussed.

Texture and mechanical properties of tape substrates from binary and ternary copper alloys for second-generation high-temperature superconductors

The process of texture formation in tapes made of a number of binary and ternary copper alloys upon cold rolling to degrees of deformation of 98.6–99% and subsequent recrystallization annealing has been studied. The possibility of designing multicomponent alloys based on the binary Cu-30% Ni alloy additionally alloyed with elements that strengthen the fcc matrix, such as iron or chromium, has been shown. The opportunity of obtaining a perfect cube texture in a thin tape made of binary and ternary copper alloys opens prospects for their use as substrates in the technology of second-generation HTSC cables. Optimum regimes of annealing have been determined, which make it possible to obtain in the Cu-M and Cu-(30–40)Ni-M (M = Fe, Cr, Mn) alloys a perfect biaxial texture with the fraction of cube grains {001}〈100〉 on the surface of the tape more than 94%. The estimation of the mechanical properties of the textured tapes of the investigated alloys demonstrates a yield strength that is 2.5–4.5 times greater than that in the textured tape of pure copper.

Cube Texture Formation in Fe–50 % Ni Thin Tapes Under Annealing in DC High Magnetic Field

The main purpose of the work is to study the recovery and recrystallization processes in cold-rolled tapes of the Ni48.8Fe51.2 alloy subjected annealing under high magnetic fields up to 20T. In the course of primary recrystallization without magnetic field, in the tapes made of this alloy, there forms a sufficiently sharp cube texture, which makes it possible to use these tapes for epitaxial deposition on them of high-temperature superconductors (HTS). In the work presented, the rolled tapes are used as a model material for investigation of structure transformations upon a new treatment mode—annealing in high direct current magnetic field. Preliminary annealings in magnetic field and, for comparison, without it were performed at temperatures both above and below the Curie temperature and, at the same time, the onset temperature of primary recrystallization. It is shown that as a result of the final annealing without magnetic field at an elevated temperature, which provides the primary recrystallization and normal grain growth, in the recrystallization texture of tapes that underwent a preliminary annealing at the temperature below the Curie point, there is observed a noticeable increase of the volume fraction of grains with the easy magnetization axis . Moreover, the retardation of recovery processes during magnetic annealing was found.

Creating textured substrate tapes of Cu-Fe alloys for second-generation high-temperature superconductors

It is established that Cu-1.6 at % Fe alloy tapes obtained through cold rolling to 98.9% followed by recrystallization annealing possess a sharp cube texture, which opens prospects of using thin tapes of this alloy as substrates for second-generation high-temperature superconductors. The optimum regime of annealing is determined that allows an alloy with sharp biaxial texture containing more than 97% cubic grains to be obtained. The yield stress of a 90-μm-thick Cu-1.6 at % Fe alloy tape upon recrystallization annealing at 800°C for 1 h amounts to 78 MPa, which is about three times higher than the value for a pure copper tape with sharp cube texture.

Effect of surface shear on cube texture formation in heavy cold-rolled Cu–45 at%Ni alloy substrates

Two types of Cu–45at%Ni alloy thin tapes with and without surface shear were obtained by different heavy cold rolling processes. The deformation and recrystallization textures of the two tapes were thoroughly investigated by electron back scattering diffraction technique. The results showed that a shear texture mainly covered the surface of the heavy deformed tapes because of the fraction between the surface of rolling mills and the thin tapes when the rolling force strongly reduced at high strain, which significantly reduced the fraction of rolling texture on the surface of the Cu–45at%Ni alloy thin tapes, retarded the cube grain growth during recrystallization and affected the strong cube texture formation after high temperature annealing.

Revisiting 2D Lattice Based Spin Flip-Flop Ising Model: Magnetic Properties of a Thin Film and Its Temperature Dependence

This paper presents a brief review of Ising’s work done in 1925 for one dimensional spin chain with periodic boundary condition. Ising observed that no phase transition occurred at finite temperature in one dimension. He erroneously generalized his views in higher dimensions but that was not true. In 1941 Kramer and Wannier obtained quantitative result for two dimensional Ising model and successfully deduced the critical temperature of the system. In 1944 Onsager explicitly obtained free energy in zero fields. Though only 1dimensional formula has been derived in this review paper but Monte Carlo simulations results verify the established part of experiment and theory and explore the temperature dependence of magnetic property of thin film in 2D case. The paramagnetic case with spin coupling coefficient J=0 and ferromagenetic cases with J=0.50, 0.75 & 1.0 are studied at temperatures kT=0.20, 0.30, 0.40, 0.50, 0.60, 1.0, 1.5 & 2.0. The change in behavior from ferro to para are also observed and explained at high T values. I have demonstrated data writing for application purpose by writing number 10 on a thin ferromagnetic tape (i.e 2D film).

Improvements in energy dispersive X-ray fluorescence detection limits with thin specimens deposited on thin transparent adhesive tape supports

The elemental detection limits observed in total reflection X-ray fluorescence analysis (TXRF) are better compared to that of energy dispersive X-ray fluorescence (EDXRF) by approximately three orders of magnitude (in pg level) mainly due to efficient excitation geometry and special features of total reflection of X-rays. Also, the matrix effects are negligible and the thin film approximation is valid for all types of specimens. The detection limits in EDXRF can be improved using thin specimens deposited on thin sample supports so that scattering and thereby background are reduced. In the present study, the detection limits in EDXRF could be improved to ng–pg level for different elements using thin specimens of the samples deposited on thin transparent adhesive tape supports. The EDXRF analytical results were in very good agreement with those of TXRF. The EDXRF detection limit achieved using this approach for Cr was found to be 1050pg compared to 320pg obtained in TXRF. For Y these values were found to be 320 and 168pg respectively. The EDXRF detection limits achieved in the present work have given a new EDXRF analysis methodology for sample analysis with detection limits comparable to TXRF using a simple instrumentation.

Detachment of compliant films adhered to stiff substrates via van der Waals interactions: role of frictional sliding during peeling.

The remarkable ability of some plants and animals to cling strongly to substrates despite relatively weak interfacial bonds has important implications for the development of synthetic adhesives. Here, we examine the origins of large detachment forces using a thin elastomer tape adhered to a glass slide via van der Waals interactions, which serves as a model system for geckos, mussels and ivy. The forces required for peeling of the tape are shown to be a strong function of the angle of peeling, which is a consequence of frictional sliding at the edge of attachment that serves to dissipate energy that would otherwise drive detachment. Experiments and theory demonstrate that proper accounting for frictional sliding leads to an inferred work of adhesion of only approximately 0.5 J m(-2) (defined for purely normal separations) for all load orientations. This starkly contrasts with the interface energies inferred using conventional interface fracture models that assume pure sticking behaviour, which are considerably larger and shown to depend not only on the mode-mixity, but also on the magnitude of the mode-I stress intensity factor. The implications for developing frameworks to predict detachment forces in the presence of interface sliding are briefly discussed.

Optimized welding parameters for Al 6061 ultrasonic additive manufactured structures

Abstract

Flexible Thermosetting Pipe

The typified as flexible thermosetting pipe, is a new product, developed initially in response to the need for a non-metallic replacement for steel pipe used for oil and gas productions. This product may use for high pressure down-hole applications in which the pipe could repeatedly transported onto a drum. The proposed pipe comprise an internal thermoplastic layer play as liner and a fluid-tight cover, and one or more dual-helical wounding tape stacks applied to the internal liner for absorbing axial and bending loads. The tape stacks are wrapped helically onto the pipe structure with adjacent gaps between wrappings tape to reduce the pressure integrity of the tubular pipe structure. The composite tape stacks are formed from a plurality of thin tape strips and are bonded to each other within a stack. All the layers are manufactured from composite material consisting of highly noncorrosive epoxied matrix reinforced by long continuous fibers. Thus, the proposed flexible pipe designed to be stand alone with thermoplastic liner over-wound with one or more of an epoxy-based structural thermosetting laminate. To this aim, a straightforward simulations of thermosetting pipe is developed via using ANSYS software. Apart from possessing an accurate operational condition, on account of its simplicity the proposed simulation seems also very suitable for further developing and prototyping purposes. Finally, it has been shown that the proposed thermosetting pipe, which partially attains some classical characteristic of both offshore and onshore pipeline by a different line of reasoning, is may serve as a reference in designing flexible pipe.

자외선 경화형 아크릴 양면 점착테이프의 두께 및 무기물 충전제 종류에 따른 접착특성

본 연구는 고성능 준구조용 양면 점착테이프 제조를 위해 2-ethylhexyl acrylate(2-EHA)와 acrylic acid(AAC)를 사용하였고, UV 조사에 의해 시럽을 준비하였다. 양면 점착테이프의 두께, 무기물 충전제 함량 및 충전제 종류에 따른 준구조용 물성에 미치는 영향을 고찰하였다. 테이프의 두께 및 젖음시간이 증가할수록 박리강도가 증가하였다. 두께가 얇은 점착테이프(<TEX>$250{\mu}m$</TEX>이하)의 경우 무기물 충전제의 true density가 낮을수록 적용시간 경과에 따라 박리강도가 높게 나타났다. 무기물 충전제 입자가 클수록 초기 박리강도가 높게 나타났으며, SEM 이미지를 통해 점착테이프 내에 무기물 충전제의 크기를 확인하였다. 다양한 무기물 충전제 및 함량에 따라 박리강도 증가와 함께 전단접착강도가 증가하는 비례관계를 보였으며, <TEX>$0.1{\mu}m$</TEX>인 양면 점착테이프에서 무기물 충전제는 전단접착강도에 더 영향을 주었다. 이러한 결과로부터 박막형 아크릴 양면 점착테이프는 준구조용 물성을 필요로 하는 용도에 사용가능할 것으로 사료된다. To manufacture of high-performance semi-structural double-sided adhesive tape, 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AAC) were used, and the syrup was prepared by UV irradiation in this study. The effects of the thickness, various inorganic filler contents, and filler types on the semi-structural properties of acrylic double-sided adhesive tape were investigated. The peel strength increased with increasing thickness and wetting time. In case of the thin thickness (under <TEX>$250{\mu}m$</TEX>) with decreasing true density of inorganic filler, the peel strength increased with increasing wetting time. The initial peel strength showed a higher value at a big size of inorganic filler, and the filler's size in adhesive tapes was confirmed by SEM images. The peel strength and dynamic shear strength increased as a proportional relationship with various inorganic fillers and contents, and these inorganic fillers in <TEX>$0.1{\mu}m$</TEX> thickness indicated more effect on the dynamic shear strength of double-sided adhesive tape. From these results the thin acrylic double-sided adhesive tape determined to be use for applications as a high-performance semi-structural.

Modeling of AC Loss in Coils Made of Thin Tapes Under DC Bias Current

Many applications, such as magnets and SMES, are usually charged and discharged under a bias DC current, which may increase the AC loss. For their design, it is necessary to understand and predict the AC loss. This article analises the AC loss in magnet-like coils under DC bias contribution super-imposed to the AC current. The analysis is based on a numerical model that takes the interaction between magnetization currents in all turns into account. The studied example is a stack of 32 pancake coils with 200 turns each made of thin tape, such as $Re$BCO coated conductor. We present the current density, the instantaneous power loss, and loss per cycle. We have found that the loss increases with the DC bias current. The instantaneous power loss is the largest in the initial rise of the the AC current. In following cycles, the power loss is higher in the current increase than in the decrease. The loss per cycle is the largest at the end pancakes. In conclusion, the highest cooling power should be supplied to the top and bottom pancakes and during current rise, specially the initial one. The presented model has a high potential to predict the AC loss in magnet-size coils, useful for their design.

Glass-Ceramic Solid Electrolytes for Lithium and Sodium Ion Batteries

Common Lithium and Sodium Batteries have crucial drawbacks in operation caused by the type of separators and electrolytes. Polymeric separators used in Li-batteries show an insufficient stability against rising temperatures and the growth of dendrites. So hot spots, internal shortcuts, and even fire can result. The used solid electrolytes for Na Batteries made of β/β’’-Al2O3 work at temperatures around 300 °C what leads to low efficacies by energy consumption for heating of the battery system. Cracks in Al2O3 separators can cause severe failure by leakage of molten sodium. For both types of batteries solid glass-ceramic electrolytes can contribute to a higher level in security and safe operation of battery systems by several superior material properties. By high mechanical strength, a precise distance between the electrodes is defined. Due to high thermal stability, thermal runaways are impeded. Glass-ceramic and ion conducting materials can be used as particles or porous solids in combination with liquid electrolytes for common batteries but gastight solid electrolytes even enable new battery concepts like lithium-air batteries. Thin and mechanical stable Na-Ion conducting electrolytes show high conductivities even at ambient temperatures and enable room temperature sodium batteries. Dense galss-ceramic solid electrolytes also enable the use of two different types of liquid electrolytes for anode and cathode compartment.In the study glasses are molten, quenched and crystallized to obtain ion conductive solid state glass-ceramic electrolytes. The material systems therefore are Li1+xAlxTi2-x(PO4)3 for Li-Ion Batteries and Na3+3x-yRE1-xPySi3-yO9 (RE: rare earth) for Na-Ion Batteries respective both are analogues of the NaSiCON-Structure. Glasses with varying ratios of Al/Ti and RE/P/Si are molten and after crystallization by different thermal treatments widely characterized (HTM; DTA; XRD; REM). Impedance spectroscopy measurements are carried out to determine the conductivity with respect to the chemical composition, thermal treatment and microstructure. Room temperature conductivities up to 10-4 S/cm will be presented and discussed. Promising compositions are processed as slurry for tape casting to gain thin and dense glass-ceramic solid electrolyte tapes for the application in room temperature Batteries.