Textured Metal Substrates Research Articles

Impact of Sterilization on the Adhesion Properties of a Polyamide 11 Coating on Textured Metal Substrates

Polyamide materials are widely used for medical device coating. However, despite the fragile area at the interface, these devices must conserve their physical and mechanical performance after the sterilization process. In this work, the impact of steam sterilization, widely used in the medical sector, on the adhesion properties of biocompatible and biosourced polyamide-11-coated copper substrates was assessed. The adhesion strength, a quantitative indicator of the coating performance, was assessed thanks to a laboratory-made bench test. The surface of metal substrates was microstructured with laser engraving to enhance the coating adhesion. The Ra roughness value was varied to verify if the depth of valleys induced with the femtosecond laser could favor the interfacial anchoring. Scanning electron microscopy analyses highlighted the physical surface evolution of the polymer analyzed at the interface, across the various texturing parameter values, Ra. Fourier transform infrared spectroscopy was used to monitor the bands specific to polyamide thermo-oxidative degradation. Elemental composition deduced from X-ray photoelectron spectroscopy carried out on the coating after mechanical debonding clearly revealed that the chemical stability of the copper substrates was affected rather than the polyamide coating. Also, we discussed the impact of the chosen sterilization parameters (steam and pressure) on the formation of copper-based species detected with this technique.

Forced drop swinging on vibrated and textured metal substrates

AbstractA new type of vibrated drop wettability mechanism on a micro‐texture surface is proposed and investigated experimentally and theoretically. In this experiment, the mechanical testing machine is used as the vibration source, and the compound control cabinet is used to adjust the vibration liquid feeding table. By comparing the apparent dynamic contact angle, it is concluded that the surface energy of the second cycle is larger than the first one. A swing model and spring‐mass system model are presented to study the vibrated drop motion pattern. The spring‐mass system model is built to analyse the adhesion force working process theoretically. The drop surface energy is transmitted by vibration. With the superposition of vibration energy, the displacement of the drop gravity centre becomes larger and larger until the drop migrates. The adhesion force drives the liquid drop to do reciprocating motion, and it changes the liquid drop dynamic wettability.

Investigation of the effects of femtosecond laser metal surface texturing on bonding of PA 6 to steel

Abstract This paper investigates the effects of femtosecond laser surface texturing on the interfacial bond strength of steel and a thermoplastic polymer PA 6 film. Ultimately the textures will be used for hybrids that are manufactured using a near-infrared (NIR) laser-assisted automated tape placement (ATP) process and carbon fibre / PA 6 composites, therefore the NIR absorptance of the textured metal substrate is also of interest. To identify the influence of different surface structures on the bonding strength, lap shear samples were manufactured with laser textures varying in pulse length, hatch distance and ablated depth and tested by ASTM D 3165. The surface structures were analysed with white light interferometry (WLI) and scanning electron microscopy (SEM). Additional optical measurements in the infrared radiation range of 900 nm to 1100 nm were executed with a spectrophotometer to evaluate the laser absorptance for the NIR automated tape placement process. The lap shear strength increased to the highest value of 31.9 MPa with a tooth shaped laser texture using a 275 fs laser pulse width, a hatch distance of 600 μm an ablated depth of 40 μm. Also the absorptance for this sample increased by approximately 13% to 73% compared to the unprocessed pickled steel.

Heteroepitaxial Cu2O thin film solar cell on metallic substrates.

Heteroepitaxial, single-crystal-like Cu2O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, earth-abundant solar cells. Here, we report epitaxial growth of Cu2O films on low cost, flexible, textured metallic substrates. Cu2O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu2O phase without any trace of CuO phase is only formed in a limited deposition window of P(O2) - temperature. The (00l) single-oriented, highly textured, Cu2O films deposited under optimum P(O2) - temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40–60 cm2 V−1 s−1 and carrier concentration over 1016 cm−3. The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu2O solar cell based on epitaxial Cu2O film prepared on the textured metal substrate.

MOCVD derived double-sided YBa2Cu3O7−δ films on Y2O3/YSZ/CeO2 buffered textured metal substrates

We have successfully employed metal-organic chemical vapor deposition (MOCVD) technique to simultaneously deposit double-sided YBa2Cu3O7−δ (YBCO) films on both sides of Y2O3/yttria-stabilized zirconia (YSZ)/CeO2 (YYC) buffered biaxially textured Ni-5 at.% W substrates, which is of great prospect to cut the production cost of YBCO coated conductors. X-ray diffraction analysis revealed that both sides of YBCO film were purely c-axis oriented and highly textured. The ω-scan of (005) YBCO and ϕ-scan of (103) YBCO yielded full width at half maximum (FWHM) values of 4.9° and 6.6° for one side of double-sided YBCO film, respectively, as well as 4.4° and 6.4° for the other side. The current transportation measurements performed on such double-sided 500 nm-thickness YBCO films showed the self-field critical current density (Jc) at 77 K of 0.6 MA/cm2 and 1.2 MA/cm2, respectively. Further research is in the process of exploring new solution to improve the Jc in practice.

The Project SupraMetall: Towards Commercial Fabrication of High‐Temperature Superconducting Tapes

AbstractsThe aim of the joint industrial and academic project “SupraMetall” is to enable the large scale production of superconducting tapes. This is a report of the recent achievements in the production of cube textured metal substrates and the coating techniques of the buffer and superconductive layers. The final coated conductor tapes of 2 m length reached critical current densities of 120 A/cm‐width.

Influence of Annealing Atmosphere on Epitaxial Growth Process of the CeO2 Buffer Layer for Coated Conductors

The epitaxial growth of the buffer layer on a textured metal substrate has a significant influence on the performance of coated conductors, which provides the potential to support a high current for electric utility and high magnetic field applications at 77 K. In this paper, we have fabricated the CeO2 buffer layer on YSZ (yttria-stabilized zirconia) (00l) single crystal substrates by the chemical solution deposition (CSD) method in different annealing atmospheres. The results show that both the thermal decomposition behavior of the precursor solution and the annealing atmosphere have an important effect on the epitaxial growth process of the CeO2 buffer layer. The large oxygen partial pressure in annealing atmosphere is to the disadvantage of the epitaxial growth of CeO2 (00l) crystal face with high energy. Moreover, the epitaxial growth of the CeO2 (00l) crystal plane goes against a decrease in the surface roughness of the CeO2 film. Therefore, it can be considered that the orientation growth of the CeO2 buffer layer and its surface morphology evolution may be related to the thermal decomposition behavior of precursor solution and the change of oxygen vacancies concentration.

A Novel All-Conductive Architecture on Biaxially Textured Metal Substrates for YBCO Coated Conductors

In order to avoid thermal destruction of the superconductor in case of overcurrent, and improve the engineering current density J E of the tapes, a novel buffer architecture, i.e., conductive SrRuO3/TiN, has been developed on biaxially textured Ni-5 at.%W substrate for YBa2Cu3O7−x (YBCO) coated conductors using pulsed laser deposition. The conductive TiN served as the effective seed and barrier layer because of low diffusion of metal atoms in the TiN layer, and the epitaxial conductive SrRuO3 with good lattice match with the YBCO material, and was used as the cap layer. The X-ray diffraction showed the TiN and SrRuO3 films had a perfect c-axis orientation and very good out-of-plane and in-plane texture. Atomic force microscopy indicated a very flat and dense TiN film with a layer-by-layer growth mode, and the root mean square surface roughness (R rms) of the SrRuO3 was less than 5 nm over a 2 μm × 2 μm scan area. The current–voltage curves of SRO/TiN/NiW showed a good conductivity of 16.7 Ω at the applied voltage of zero.

Development of 66kV class REBCO superconducting cable

Abstract Sumitomo Electric Industries (SEI) has been involved in the development of 66 kV/5 kA-class HTS cables using REBCO wires. One of the technical targets was to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI developed a clad-type textured metal substrate with lower magnetization loss than NiW substrates. REBCO wires of 30 mm wide were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The measured AC loss of the manufactured cable was 1.8 W/m/phase at 5 kA, achieving the AC loss goal. Another important target was to manage fault current. The copper protection layers were designed based on simulation findings. Fault current tests (max. 31.5 kA, 2 sec) showed that the designed HTS cable has the required withstanding performance. The development of the elemental technologies was finished on schedule, and a 15 m-long HTS cable system will be constructed to demonstrate that it meets all the required specifications.

Design and Evaluation of 66 kV-class “3-in-One” HTS Cable Using REBCO Wires

Abstract Sumitomo Electric (SEI) has been involved in the development of 66 kV-class HTS cables using REBCO wires. One of the technical targets is to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI has developed a clad-type textured metal substrate with lower magnetization loss than NiW substrate. REBCO tapes 30 mm-wide were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The measured AC loss of the manufactured cable was 1.8 W/m/phase at 5 kA, achieving the AC loss goal.

Formation of Nanoparticles in Zr and Dy Doped YBCO MOD Superconducting Films

We study the formation mechanism of nanoparticles in thin films of the superconductor YBa2Cu3O7-δ(YBCO). We form the films by metal-organic deposition (MOD) on buffered, textured metal substrates. Through the addition of Dy or Zr salts to the precursor solution we precipitate (Y,Dy)2O3and BaZrO3nanoparticles, uniformly distributed through the film thickness. By quenching samples during the film growth, we show the nanoparticles form in the precursor layer before YBCO growth. The size of the nanoparticles was quantitatively analysed by TEM. We found that Zr doping produces smaller nanoparticles than Dy doping.

Study of MgO-Based Buffer Layer Architecture for the Development of Ni–Cu-Based RABiTS YBCO Coated Conductor

MgO films are widely used as the first buffer layer in IBAD-YBCO coated conductors, whereas there are only a few examples of its use in RABiTS YBCO coated conductors. Nevertheless MgO, though challenging in terms of lattice parameter and epitaxy, can effectively passivate the metal substrate thus enabling the use of Ni-Cu-based alloy tapes. Such substrates develop a very sharp cube texture and at the same time can be safely handled when their thickness is as low as 40 μm. Epitaxial MgO films were deposited by e-beam evaporation at 400 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C on biaxially textured metal substrates. A transient Pd layer as thin as 10 nm was used to alleviate the lattice mismatch between MgO and the substrate and to enhance film adhesion. Due to the reduced diffusion of oxygen in MgO, this template is effective against substrate oxidation even in the extreme conditions typical of the YBCO growth. On such a template, La <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.66</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.33</sub> MnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LSMO) was epitaxially deposited by PLD. Moreover, BaZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (BZO) film was successfully deposited by CSD on MgO single crystal and is expected to epitaxially grow also on MgO film.

Design and evaluation of 66 kV-class HTS power cable using REBCO wires

Sumitomo Electric (SEI) has been involved in the development of 66kV-class HTS cables using REBCO wires. One of the technical targets in this project is to reduce the AC loss to less than 2W/m/phase at 5kA. SEI has developed a clad-type of textured metal substrate with lower magnetization loss compared with a conventional NiW substrate. In addition, 30mm-wide REBCO tapes were slit into 4mm-wide strips, and these strips were wound spirally on a former with small gaps. The AC loss of a manufactured 4-layer cable conductor was 1.5W/m at 5kA at 64K. Given that the AC loss in a shield layer is supposed to be one-fourth of a whole cable core loss, our cables are expected to achieve the AC loss target of less than 2W/m/phase at 5kA. Another important target is to manage a fault current. A cable core was designed and fabricated based on the simulation findings, and over-current tests (max. 31.5kA, 2s) were conducted to check its performance. The critical current value of the cable cores were measured before and after the over-current tests and verified its soundness. A 5kA-class current lead for the cable terminations was also developed. The current loading tests were conducted for the developed current leads. The temperature distribution of the current leads reached to the steady-state within less than 12h, and it was confirmed that the developed current lead has enough capacity of 5kA loading.

Lateral critical current density distributions degraded near edges of coated conductors through cutting processes and their influence on ac loss characteristics of power transmission cables

The critical current density (Jc) near the edges of coated conductor could impact the ac loss characteristics of the cables comprising coated conductors. A wide coated conductor is often cut into narrower coated conductors in fabrication processes, and the Jc might degrade near the edges of coated conductors through the cutting process. This possible degradation of Jc could depend on cutting technology. Lateral Jc distributions of coated conductors cut by using a mechanical slitter as well as a laser were measured by the magnetic knife method. The measured coated conductors are fabricated by PLD process on clad type textured-metal substrates with reduced magnetism. Based on the degradation of Jc near the edges of coated conductors which was determined experimentally, ac losses of multi-layer cables as well as mono-layer cables were calculated numerically to evaluate the impact of the Jc degradation near the edges of coated conductors on the their ac loss characteristics.

30 mm wide process of GdBCO PLD/clad-type textured metal substrates

Gd1Ba2Cu3Ox (GdBCO) coated conductors using bi-axially textured clad-type substrates have been developed for high temperatures superconducting (HTS) power cables. In this project, large amount of coated conductors (CCs) are necessary for the several tests of basic properties of HTS power cables and the fabrication of a 15m long 3-in-one HTS model cable. In order to ensure an adequate amount and properties of coated conductors, the stable manufacturing technology and the high production rate at each process are required.In this report, we have newly installed a high power laser of 300W for the PLD system, resulting in improvement of the manufacturing stability and the deposition rate for GdBCO film. In addition, we have optimized target–substrate distance in PLD process, and the uniformity of Ic distribution across 30mm wide tapes were remarkably improved. Furthermore, the surface morphology of buffer layers were enhanced by optimizing the deposition condition using electron beam (EB) evaporation method, and the maximum Ic value for a short sample has achieved 497A/cm at 77K in the self-field. Based on these progresses, we are currently developing the stable manufacturing process for long CCs with over 400A/cm.

Integrated pinning centers in YBa2Cu3Ox thick films on single-crystalline and textured metal substrates

The second-generation coated tapes of high temperature superconductors (HTS) deposited on textured metal substrates strongly rely on the introduction of extended nano-defects in order to enhance their critical current. A proven effective way to introduce such defects is growing BaZrO3 (BZO) nano-rods and an alternative way is to generate HTS columnar growth using nanoparticles of noble metals. Here we report the combination of these methods. It allows achieving controlled pinning and high critical current in YBa2Cu3Ox films deposited on single crystal substrates and significantly improves critical current in coated conductors deposited on rolling-assisted biaxially-textured metal substrates (RABiTS). The superconducting properties of thick (up to 5 micron) conductors are analysed using DC-magnetisation, AC-susceptibility and angle-dependent transport measurements. TEM imaging is used to confirm the presence of extended defects in the tapes.

Single cerium zirconate buffer layer on biaxially textured metal substrates for high performance coated conductors

Textured cerium zirconate (Ce x Zr1−x O2) films were deposited on biaxially textured Ni-5at.%W substrate by direct-current (dc) reactive magnetron sputtering for low cost production of high performance YBa2Cu3O7−δ (YBCO) coated conductors. Film composition was controlled by modulating dc power applied to the Ce metal target. X-ray diffraction analysis shows that all the samples exhibit epitaxial growth, with c-axis perpendicular to the substrate surface. The YBCO film deposited directly on the Ce0.32Zr0.68O2 layer for optimized lattice matching shows a transition temperature T c and critical current density J c (75.5 K, self field) of 90.4 K and 1.3 MA/cm2. The in-field dependence of J c is similar to the standard CeO2/YSZ/CeO2 buffered samples. These results demonstrate that a single Ce x Zr1−x O2 buffer layer, instead of CeO2/YSZ/CeO2 multi-buffer layers for the fabrication of YBCO coated conductors, provides advantages such as simplified architecture and potentially reduced cost due to the reduced fabrication steps.

AC loss characteristics of RE-123 superconducting cable

High temperature superconducting (HTS) cables with RE-123 coated conductors are expected to lower AC loss compared to that with BSCCO cable. Sumitomo Electric Industries, Ltd. (SEI) has been developing not only BSCCO wires but also RE-123 coated conductors. Recently, SEI has developed a RE-123 coated conductor with a new type of textured metal substrate (Clad-type). The clad-type substrate has lower magnetization loss and higher mechanical strength compared with a nickel alloy substrate. To clarify the potential of this novel substrate for AC cable application, a 2-layer cable conductor was manufactured. It shows good AC loss characteristics, and the measured AC loss was less than 0.1 Wm−1 at 1 kArms and 60 Hz. The influence of the magnetism of the clad-type substrate on AC loss in the cable conductor is much smaller than that of nickel alloy substrate. The novel coated conductor with clad-type substrate is suitable for AC cable application.

Development of buffer layers on 30 mm wide textured metal substrates for REBCO coated conductors

We have been studying REBa2Cu3Ox (RE: rare earth elements) coated conductors on clad-type substrates. We developed coated conductors on the 10mm wide clad-type tape, and succeeded in obtaining the maximum critical current of 380A/cm with the 2.0μm thick GdBa2Cu3Ox superconducting film. At present, we are trying to widen the tape width from 10mm to 30mm in order to increase production throughput. We report our recent progress on scaling-up of the buffer layers and their properties.The buffer layers consisted of three layers; CeO2 as the seed layer, yttrium-stabilized zirconia (YSZ) as the diffusion barrier layer and CeO2 as the lattice matching layer. They were grown by the RF-sputtering method and the electron beam evaporation technique (EB). EB deposition has possibility of higher throughput compared with the RF-sputtering. The intensity ratio of (200) to (200)+(111) for the lattice matching layer showed as high as 98%. The uniform properties of 40m long and 30mm wide substrates were successfully produced by all sputtering method. Additionally, the tape travel speed of the seed layer can be increased from 7m/h (RF-sputtering deposition) to 10m/h (EB deposition) on short sample (0.3m long).

Germanium films with strong in-plane and out-of-plane texture on flexible, randomly textured metal substrates

High efficiencies have been achieved in photovoltaic cells based on III–V compounds grown on single crystal germanium substrates. Since the size of these substrates is limited and their cost is very high, such III–V photovoltaics have not found widespread terrestrial use. The objective of this work is to develop highly textured, epitaxial germanium thin films on inexpensive substrates suitable for roll-to-roll continuous processing to serve as templates for III–V compounds. Germanium films with a high degree of in-plane and out-of plane texture have been demonstrated on randomly textured, flexible nickel alloy substrates by epitaxial growth on template films made by ion beam-assisted deposition (IBAD). In order to achieve epitaxial growth, an intermediate layer of CeO 2 was found to be required between the IBAD MgO template and the Ge film. Our study shows that structural match between Ge and the underlying oxide layer is the key to epitaxial growth. Room temperature optical bandgap of the Ge films was identified at 0.67 eV suggesting minimal residual strain in the film. Refraction index and extinction coefficient values of the epitaxial Ge film were found to match well with that measured from a reference Ge single crystal.