Production Of Tapes Research Articles

Multi-chamber deposition system for continuous production of YBCO coated conductors by thermal co-evaporation

We recently reported on a simple thermal co-evaporation route based on a reel-toreel system, that enables the production of 2 m-long superconducting tapes with Ic values up to 120 A/cm-width (Jc = 2 MA/cm2) and Tc = 88 K. This work describes the development of a new multi-chamber system designed for the continuous production of these tapes suitable for an industrial process. The system consists in three distinct vacuum chambers connected one with another by two specially designed 50 cm long slits. The length and cross-section of these slits have been calibrated in order to achieve a pressure difference up to 5 orders on magnitude across adjacent chamber. The system is originally conceived for the continuous production of CeO2 buffered RABiTS Ni-based tapes that require a pre-treatment of the bare metallic tapes in forming gas, followed by CeO2 deposition and a post-treatment in oxygen. To improve the robustness of the whole tape production process, we have designed and built a novel device based on a supersonic oxygen gas expansion for the continuous in situ oxygenation of YBCO during deposition. Here, we present preliminary results demonstrating the effectiveness of this device. Specifically, thanks to the enhancement of the number of collisions of the O2 molecules with the substrate due to the focused supersonic beam, we find that the oxygen pressure in the vicinity of the substrate can be up to 3 orders of magnitude higher than the background pressure in the chamber. The main advantage of this supersonic device is the insensitivity of the effective pressure to the substrate-nozzle distance, in the 2-5 mm range, which can be easily controlled during a continuous production process.

Beyond Stereotypes

Red tape is a significant management challenge, and this article seeks to understand how some managers are able to better cope with it. The authors find that managers with positive work attitudes cope better with personnel constraints as compared to those who have less positive work attitudes. The findings cast doubt on stereotypes depicting public managers as being engaged in aggressive red tape production or slothful permitting of red tape. The authors conclude by suggesting that future research should steer away from relegating study of red tape to the realm of negative stereotypes. Instead, managerial and organizational responses to red tape should be studied as part of the normal.

Progress on TFA-MOD coated conductor development

The recent progress in coated conductor development by the TFA-MOD process was reviewed. Much progress was recognized in the R&D on TFA-MOD processing for satisfying several requirements, such as high superconducting performance, long tape production, high production rate, etc., considering the real application. For high superconducting performance, the high Ic value of 413A was achieved in a short sample with an architecture of MOD-YBCO/IBAD-GZO/IBAD-GZO/Hastelloy. It was realized by improving the in-plane crystal grain alignment of the CeO2 buffer layer and optimizing conditions of the heat treatments in the calcination and crystallization processes. In the calcination process, it was found that lower heating rate was effective to improve the morphology of the multi-layered precursor by preventing from pore generation and segregation of Cu elements. In the crystallization process, it was found that high humid gas partial pressure was effective to improve the Jc values by reducing the amounts and size of pores in the YBCO layers. Furthermore, in the case of thicker firm, it was found that the low heating rate in the crystallization process was effective to prevent from the crack formation. On the other hand, in order to obtain the long tape with uniform Ic values, in the crystallization process, the gas flow condition in a large scale equipment for the continuous long tape process was investigated using a computer simulation technique. Consequently, the 8.6m YBCO on PLD-CeO2/IBAD-Gd2Zr2O7/Hastelloy tape which shows high Ic performance of 119A as an end-to-end value at 77.3K in self fields, was successfully obtained. As a result, Ic×L(length) value of 1024 Am was achieved.

Brady Corp.

AbstractConsumer Accessories (MIC: 4.6 SIC: 993 NAIC: 39950)Brady is an international manufacturer and marketer of identification products and specialty materials. Co.'s products include labels and signs, printing systems and software, label‐application and data‐collection systems, safety devices and precision die‐cut materials. Co.'s major products include identification applications and specialty tape products, including wire and cable markers, high‐performance labels, laboratory identification products, stand‐alone printing systems, bar‐code and other software, graphics and workplace applications. Co. serves customers in electronics, telecommunications, manufacturing, electrical, construction, education and other industries.

SENSITIVITY OF THIN-WALLED DRIP TAPE EMITTER DISCHARGE TO WATER TEMPERATURE

One of the primary goals in the design of microirrigation systems is to have a hydraulic balance to ensure uniformemitter discharge. However, while most design processes focus on pressure distributions and changes associated with frictionand elevation differences, elevated water temperatures will change the physical properties of the water and may change thephysical properties of some emitters. Laboratory studies were conducted to measure the effects of water operating temperatureon the sensitivity and discharge rate of emitters from thin-walled drip tape (collapsible emitting hose) products. Two differentproduct types (Roberts Ro-Drip, RD; and T-Tape, TT,) each with two wall thicknesses, were evaluated. The RD productincluded wall thicknesses of 0.20 mm (8 mil, RD-08) and 0.38 mm (15 mil, RD-15), whereas the TT product included wallthicknesses of 0.25 mm (10 mil, TT-10) and 0.38 mm (15 mil, TT-15). Additional characterization tests included a standardoperating pressure/emitter discharge rate test and a tubing tensile stress (elongation) test. All tests were conducted inaccordance with ASAE Standard S553, Collapsible Emitting Hose (Drip Tape) Specifications and Performance Testing.Increases in water operating temperature from 21.C to 50.C resulted in an 18%, 44%, and 97% increase in emitter dischargefrom the RD-08 product at operating pressures of 55, 69, and 83 kPa, respectively. Emitter discharge rate changes in theRD-15 product were not as great (10 to 12% increase) for similar water temperature changes. Effects of water temperatureon the discharge rate from the TT products were quite different from the RD products. Emitter discharge rate increasedslightly(<5%) with water temperature at 55 kPa, but decreased by up to 7% at 83 kPa. TDR values (also referred to as atemperature flow rate index) relate the emitter discharge at each measured temperature value (qt.) to the emitter dischargeat the initial base temperature (q20.) [TDR = (qt.)/(q20.)]. In this work, the RD-08 product had a quadratic relationshipbetween temperature discharge ratio and water temperature, while the RD-15 product and both TT-10 and TT-15 productshad more linear relationships.<br><br>Designers of microirrigation systems need the hydraulic performance characteristics of the products that they areconsidering in a system design. Such information should come from the manufacturers of the various collapsible emitting hose(drip tape) products. Product information should clearly provide physical characteristic data such as the emitter exponentx, constant of proportionality k, temperature discharge ratio values, and maximum recommended operatingtemperature.

Environmental impact of the MV CITA on the foreshore of Porth Hellick, Isles of Scilly

The grounding of the container feeder vessel MV CITA on Newfoundland Rocks, Isles of Scilly, had an effect on the surrounding biota and benthic environment. Included in the CITA’s cargo were five 40 ft containers holding pallets of polyester film used in the production of audio and visual recording tapes. The wreckage presented a minor but potentially chronic source of pollution through the delayed release of polythene film, which was left on the seabed as it was considered insufficiently valuable to warrant salvage. The polythene disintegrated and was washed upon the foreshore of Porth Hellick in minute shreds. The adjacent foreshore and two control sites within the islands were analysed using a 5-strand line and vegetation survey with 10 random quadrats within each line to determine the environmental impact of the polythene.

Brady Corp.

AbstractConsumer Accessories (MIC: 4.6 SIC: 3993 NAIC:339950)Brady is an international manufacturer and marketer of identification products and specialty materials. Co.'s products include labels and signs, printing systems and software, label‐application and data‐collection systems, safety devices and precision die‐cut materials. Co.'s major products include identification applications and specialty tape products, including wire and cable markers, high‐performance labels, laboratory identification products, stand‐alone printing systems, bar‐code and other software, graphics and workplace applications. Co. serves more than 300,000 customers in electronics, telecommunications, manufacturing, electrical, construction, education and other industries.

Software aspects of the Na59 experiment

The NA59 experiment on the CERN SPS-H2 beamline took data during the summers of 1999 and 2000, to investigate the creation of circularly polarized photons starting from unpolarized electrons. The computational hub for the experiment was Northwestern University, where two clusters of computers served for the Monte Carlo simulation of the experiment, the production of the data summary tapes, and the offline data analysis. After reconstructing about half a million e/sup +/e/sup -/ pairs and comparing the results with the theoretical predictions, our experiment was first to show the birefringence property of the crystals for the photons in the 30-170 GeV range. This paper presents the newly developed methods in the event reconstruction and offline data analysis.

Processing for long YBCO coated conductors by advanced TFA-MOD process

The long tape process was developed using the advanced TFA precursor solution. In a long tape production, the advanced TFA precursor solution was coated by a die-coater using the reel-to-reel system, and the multi-coating method was applied for thicker film fabrication. We successfully fabricated long uniform precursor films. In the high temperature treatment, a large scale equipment for the continuous long tape process was developed. This equipment had a perpendicular gas flow system to the tape length which is effective to fabricate the uniform films. I c values and its distribution in the YBCO tape fabricated by this method on CeO 2/IBAD-Gd 2Zr 2O 7/Hastelloy were measured. And the uniform and high performance was confirmed. A 0.25 m long YBCO film with 1.38 μm in thickness on the metal substrate shows the high I c performance of 210 A with end to end at 77.3 K in self-fields.

Brady Corp.

AbstractConsumer Accessories (MIC: 4.6 SIC: 3993 NAIC:339950)Brady is an international manufacturer and marketer of identification products and specialty materials. Co.'s products include labels and signs, printing systems and software, label‐application and data‐collection systems, safety devices and precision die‐cut materials. Co.'s major products include identification applications and specialty tape products, including wire and cable markers, high‐performance labels, laboratory identification products, stand‐alone printing systems, bar‐code and other software, graphics and workplace applications. Co. serves more than 300,000 customers in electronics, telecommunications, manufacturing, electrical, construction, education and other industries.

Processing for long YBCO coated conductors by TFA-MOD process

The metal organic deposition (MOD) process of YBa 2Cu 3O 7− X (YBCO) using metal trifluoroacetate (TFA) precursors is considered to be a strong candidate as a low cost fabrication process in coated conductors since the TFA-MOD process is a non vacuum process and can provide high J c films. In order to develop long tape conductors using this process, the influence of the gas flow direction in the heat treatment was investigated. The J c value decreases toward to leeward side in the case of the parallel gas flow condition. On the other hand, in the case of the perpendicular gas flow condition. The J c value reveals uniformity in all over the tape and the high J c level is maintained. In the case of long tape production, it was found that the perpendicular gas flow to the tape length is effective to fabricate the uniform films. It could minimize the influence of consumption of H 2O and generation of HF gas in the up-stream area to the leeward region. The J c and I c properties and these distribution of the YBCO tape fabricated by this method on CeO 2/IBAD-Gd 2Zr 2O 7/Hastelloy is presented. Furthermore, a large scale equipment for the continues long tape process was developed based on the above findings. Consequently we have fabricated a 1 m long Y123 tape conductor by a reel to reel system. Even in the first trial, the uniform reaction for the entire length was recognized.

Development of RE123 coated conductor by ISD method

High rate deposition of HoBa 2Cu 3O 7− δ (HoBCO) layers using the pulsed laser deposition method were experimented for long high temperature superconducting (HTS) coated conductor. Laser conditions and oxygen ambient during HoBCO deposition were precisely inspected. This revealed that the deposition rate of HoBCO reached to 5 μm/min. Even at such high deposition rate, the J c of HoBCO films remained over 10 5 A/cm 2 on the biaxial buffered substrate fabricated by the inclined substrate deposition (ISD) method. Moreover continuous tape production equipments were installed to make a long and flexible coated conductor by ISD method. These equipments will enable us to fabricate of over 100 m long coated conductor. 55 m long coated conductor were fabricated by using these equipments as our first trial of long length fabrication. Evaluation of J c distributions of 55 m coated conductor revealed that all parts of 1 m in the 55 m conductor had the J c over 10 4 A/cm 2.

Bi-2223 tapes - specific performance for different applications

In the past (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ Ag/Ag-alloy-sheathed High-Temperature Superconductor (HTS) tapes (Bi-2223 tapes) have been proven being suitable for building quite different system components for a variety of applications. Nevertheless it revealed that applications like Power Transmission Lines, Transformers, Motors/ Generators, SMES, very high field magnets and MRI put very special requirements on the tapes which differ from application to application. The most important point is that the tapes will provide cost-efficient performance for the special application. This means that it's not sufficient to analyze the price in $/kAm, but additionally it's necessary to consider e.g., AC-losses, geometry, mechanical strength and insulation properties and how they contribute to cost. We discuss a subset of the different requirements from the view of a tape supplier. We depict the current status of the tape production unit lengths >1000 m, overall current densities /spl ges/100 A/mm/sup 2/, steep E-I-characteristics n-value /spl ges/30 at standard conditions and even at low temperatures and/or high magnetic fields), low AC-losses combined with remarkable critical currents of 50 A/mm/sup 2/, reliable properties of mechanics and insulation.

Evaporation––the way to commercial coated conductor fabrication

The evaporation technique is one of the most promising candidates for an industrial scale production of coated conductors. It allows high volume deposition rates, is robust and reliable––advantages which directly translate into cost savings. A reel to reel prototype deposition system has been developed and successfully tested. Continuous deposition on meter long RABiTS and inclined substrate deposition tape samples yields critical current densities up to 0.3–0.4 MA/cm 2 from end to end. On short samples deposition rates up to 5 nm/s have been realized and hence due to the large accessible deposition area tape production speeds in excess of 100 μm cm 2/min appear to be feasible in the near future.

DLC-based wear protection on magnetic storage media

The high storage capacity of flexible storage media requires the use of very thin write-and-read heads in order to function successfully. Such sensitive heads would be destroyed relatively quickly by the abrasive effect of tapes or floppy disks. Therefore, wear protective coatings were investigated in terms of their ability to reduce the wear damage caused to recording heads by tapes or floppy disks. The best-known example of the application of wear protective coatings on data storage media is in the production of hard disks. The following project was devised in order to examine whether the very thin wear protective coatings, employed successfully in hard disk production, could also be applied as a protective coating in the production of tapes and floppy disks in which the magnetic pigment used incorporates metal particles (MP). The experimental wear protective coating layer was applied to a digital-Betacam-SP tape. Adhesion failure at the interface between the magnetic head and the tape surface resulted, eventually, in the failure of the tape. Floppy disks, with a storage capacity of more than 100 MB, were also coated and tested. The coating caused a reduction in the disk's voltage level at the reading head, and other magnetic values recorded confirmed the quality reducing influence of the DLC layer on the floppy disk. The results obtained from long-term coated floppy disk tests were comparable to the results obtained in similar tests on uncoated floppy disks. The experiments proved that a DLC protective coating could be developed which would make a further improvement in the storage media systems possible, using high quality tapes and floppy disks. The major obstacle remains the elimination of the tape's adhesion problems caused by the lubricant component of the storage medium.

Biaxially textured NiCr X ( X=W and V) tapes as substrates for HTS coated conductor applications

In recent years, world-wide research efforts have been made to develop YBCO coated conductors for high T c superconductor application in large scale devices. Since the demonstration of the rolling assisted biaxially textured substrates (RABiTS) route as a viable approach for the production of long HTS tapes, much work has been directed towards the development of new metallic substrates for high critical current densities coated conductors. The present work is focused in development of novel non-magnetic, high oxidation resistance, biaxially textured Ni based alloys. High purity Ni–Cr–W and Ni–Cr–V alloys were prepared by plasma arc furnace and the (0 0 1)[1 0 0] low thickness tapes were formed by recrystallization after heavy cold rolling. The microstructure of the tapes was investigated by θ–2 θ and pole figure X-ray analysis. The strength of the tapes was measured by stress–strain curves and thermogravimetric analyses were carried out to study oxidation properties of these alloys. The surface morphology of oxidised tapes has been studied by optical and SEM microscopy.

Theoretical analysis of HTS windings made of Bi(2223)/Ag tapes prepared by a tape-in-rectangular tube technique

Anisotropy in I/sub c/(B) characteristic of Bi(2223)/Ag tapes results in a considerable decrease in magnet critical current, if the magnet winding is only made with the multifilamentary tape prepared by a standard powder-in-tube (PIT) technique. In case of cylindrical windings, the turns in pancake coils, which are located at the magnet ends, have lower critical currents than those in the other parts of the winding. In order to eliminate this undesired effect, an intensive effort is exerted to develop the tapes which have the filaments with the c-axis oriented in some other direction than the perpendicular one to the broad tape face of the tape is. In this work we present the results of calculations of critical currents of individual turns if such tapes, prepared by a novel tape-in-rectangular tube (TIRT) technique, are utilized in different parts of the winding. The analysis shows that the magnet design has always to be carried out with respect to both the magnetic field distribution in the winding and the specific properties of the tape to be used. This means that the orientation of the filaments in the TIRT tape of each pancake is to be determined with respect to the properties of the local magnetic field. This technology, which may lead to higher critical currents of individual turns, and consequently to higher critical current of the magnet, is discussed together with the natural limitations of engineering current density with respect to practical aspects of applying tape-in-rectangular tube technique to production of the Bi-based tapes with specifically oriented filaments.

Scale up of a single source MOCVD system for deposition of YBCO onto travelling tapes

MOCVD is a promising economic method for the production of YBCO tapes. An enlarged single source MOCVD-system for continuous deposition of YBCO on metal tapes was developed. Computer simulations with FLUENT code were used for the design of the new tape system, which is based on a former small tape system. The calculated temperature distribution, precursor mole fractions and gas flows lead to a better understanding of the important aspects of the design. In this new system single crystals, IBAD buffered tapes and buffered textured Ni-tapes were transported through the deposition zone and coated with YBCO. On Single crystals, IBAD buffered substrates and textured Ni the best critical current densities at 77 K of the 300-500 nm thick YBCO films were 4.8 MA/cm 2 , 2.5 MA/cm 2 and 0.25 MA/cm2 respectively. The velocity for the tape transport was 4 m/h for these substrates. The XRD-measurements of the YBCO-film on single crystalline LaAIO 3 showed only c-axis orientation with FWHM(005) = 0.10° for the rocking curve and with FWHM(102) = 0.7° for the phi scan.

High performance superconducting Y-Ba-Cu-O tapes produced by oxidation of metallic precursors

A metallic precursor fabrication route has been developed for the production of multifilamentary tapes of textured YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// in a silver matrix. The number of filaments in prototype tapes ranged from 10 to 1024 with filament thickness from 1 to 40 microns. Following low temperature oxidation of the metallic precursor, we explored conditions for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// formation similar to those used in the growth of epitaxial thin films. The YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// phase was observed to grow near the Cu/sup I//Cu/sup II/ boundary. The growth step was followed by a low temperature anneal in one atm of oxygen. J/sub c/ and T/sub c/ values were found to depend strongly on processing conditions. With optimum processing, a T/sub c/ of 90 K and a J/sub c/ of 20kA/cm/sup 2/ at 65 K, were measured. XRD patterns of chemically etched surfaces of the processed tapes gave some evidence for epitaxial alignment of the YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// with the pre-textured silver matrix.

Carbon Species and Precise Elemental Analysis of Precursors for Superconducting (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x Tapes

The chemical composition of BiPbSrCaCuO precursors prepared by different syntheses has to be checked analytically before further application to production of superconducting (Bi,Pb)2Sr2Ca2Cu3Ox tapes. Carbon species in concentrations below 0,1%(w/w) were observed to be possibly a source of gas evolving reactions during the heat treatment procedures for the superconducting phase formation. A method that allows the temperature controlled detection of CO2 resulting from reactions of various carbon species was developed based on an commercial C/H2O-analyser with IR gas detectors. By means of this method it is possible to relate the carbon content to the conditions of synthesis and technological steps of the tape production. The phase formation mechanism of the superconducting (Bi,Pb)2223 phase from a multiphase precursor strongly depends on its elemental composition. Titrimetric and ICP spectrometric methods that allow the determination of the content of the main components Bi, Pb, Ca, Sr, and Cu with high precision and accuracy were developed and their results were compared. The best results were obtained with a combined chemical-spectrometric procedure. The relative standard deviations (RSD) for all metallic elements do not exceed 1%. The analytical results of the main components and specific trace determinations are essential for the functioning of superconducting tapes.