Stainless Steel Foil Research Articles

Estimating Li-ion storage in semiconducting nanocomposite of 2D-MoS2 decorated aluminum nitride nanoflowers for flexible electrodes of supercapacitors

By combining the exclusive characteristics of a two-dimensional MoS2 layered material with a conventional key material, aluminum nitride (AlN), a flexible supercapacitor electrode can be realized. We present a bendable electrode that is straightforwardly grown on stainless-steel foil via a binder-free sputtering route. The inherent merits of good conductive pathways among MoS2 nanolayers and enriched pseudocapacitive and dielectric activity from AlN nanoflowers enable synergism of the intermixed porous structure. This unique surface morphology facilitates sulfur and nitrogen edges to make insertion/de-insertion of Li-ions more feasible to store electrochemical energy. The MoS2-AlN@SS hybrid working electrode achieves a gravimetric capacitance of 372.35 F/g at a 5 mV/s scan rate with a wide potential window of 2 V in a 1 M Li2SO4 electrolytic aqueous solution. The composite thin film of better adhesion with the current collector exhibits a remarkably high specific power of 28.05 W h/kg at a specific power of 0.26 kW/kg, simultaneously an advanced cycling lifespan of 93% over 5000 charge–discharge cycles. The capacity of the hybrid electrode is almost unperturbed under bending from 0° to 175°, while only ∼5% degradation in capacitance was noticed at a flexing angle of 175°. These distinctive features of this electrode material elucidate the practical applicability and recommend it as a promising candidate in wearable bendable supercapacitors.

Deposition and characterization of silicon thin film on stainless steel by electron beam evaporation

Silicon (Si) is a promising material as anode electrode because of its high theoretical capacity of 3579 mAh g−1 and low electrode potential (< 0.4 V vs. Li/Li+). In this paper, the Si thin film electrodes were fabricated by using electron beam evaporation on the stainless steel (SS) foil at room temperature. The structural and electrochemical characterization were investigated for the Si thin film electrodes before and after annealing at 700 ˚C. X-ray photoelectron spectroscopy analysis revealed that the annealed film layer consisted of SiOx containing about 30 at.% oxygen. The annealed Si thin film electrode resulted in improved electrochemical performance compared to as-deposited Si thin film electrode. The Si thin film electrode after annealing exhibited an initial discharge capacity of 2270 mAh g−1, and sustained excellent cycle stability with retention capacity about 95 % for 100 cycles at 0.5 C-rate. The improvement in cyclability for the annealed Si thin film electrode can be attributed to the enhanced adhesion of Si thin film to SS substrate through interdiffuion at the Si/SS interface owing to the post-annealing process.

Constitutive Model of the Surface Roughening Behavior of Austenitic Stainless Steel.

The martensitic phase transformation (MPT) is one of the most important factors that enhances the surface roughening of stainless-steel thin metal foils (TMF), such as SUS 304, compared to others without MPT, even in the same plastic strain. However, the conventional roughening model does not take into account the influence of MPT. In this study, the authors proposed a new constitutive model to express the surface roughening by taking the influence of MPT into account. The volume fractions of MPT for TMF of SUS304 in various grain sizes are accounted for quantitatively after the tensile test at room temperature and an elevated temperature, and the effect of MPT on the surface roughening is evaluated in comparison to using TMF of SUS316, in which MPT does not occur during plastic deformation. Then, a constitutive model of the surface roughening based on the experimental results is successfully built.

Fabrication of in situ alkali doped flexible CIGSSe solar cells by using aqueous spray deposition

Flexible Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells were fabricated on stainless steel foil by using aqueous spray deposition method. Since stainless steel foil is used, external alkali doping is necessary to passivate defects in CIGSSe absorber. We investigated effects of (Na, K) co-doping and selenization temperature on solar cell performance. With co-doping of Na and K, defect states were passivated significantly and highest power conversion efficiency (PCE) was obtained. However, at higher K concentration of more than 0.5%, different growth mode of CIGSSe was observed and deep defect states were developed, decreasing PCE. In addition, selenization temperature effects were studied by varying selenization temperatures. With higher selenization temperature, defect passivation for the CIGSSe absorber was more apparent, which facilitated increase of open circuit voltage. However, short circuit current was observed to be decreased at higher selenization temperature of 570 °C. This work demonstrates in-situ alkali co-doping into CIGSSe absorber with simple and low-cost spray deposition in an air environment.

Growth of uniform CuCo2O4 porous nanosheets and nanowires for high-performance hybrid supercapacitors

In this work, uniform CuCo2O4 nanowires (CCO-NWs) and nanosheets (CCO-NSs) were directly grown on the stainless-steel foil via a hydrothermal process with a post calcination treatment in air, and powdered CuCo2O4 materials were obtained once they were peeled off from the stainless-steel substrate. These NWs- and NSs-based powders possessed a huge specific surface area and mesoporous feature. After electrochemical tests, it was found that the CCO-NWs delivered a capacity of 299.12 C g−1 and CCO-NSs could exhibit a capacity of up to 332.18 C g−1. A hybrid supercapacitor (HSC) was assembled with activated carbon (AC) as anode to evaluate the practical applications of CuCo2O4 in energy storage. The CCO-NWs//AC HSC exhibited an energy density of 36.16 W h kg−1 at 1.01 kW kg−1, and as for the CCO-NSs//AC HSC, it delivered 38.46 W h kg−1 at the power density of 1.03 kW kg−1. Both HSCs showed excellent cycling performance over 5000 cycles at 6 A g−1. The superior electrochemical performance of CuCo2O4 NWs and NSs indicates that the battery-type CuCo2O4 electrode materials can serve as advanced cathode for high-performance supercapacitors, and the simple synthetic method can be extended to the preparation of other transition metal oxides (TMOs)-based electrode materials with uniform structure and impressive electrochemical properties.

Thermofluid characterization of nanofluids in spray cooling

The current study addresses a parametric characterization of nanofluid sprays as a way to improve the thermal performance of spray cooling systems. The nanofluids are prepared using as base solution of distilled water with 0.05% (m/m) cetyltrimethylammonium bromide – CTAB in which nanoparticles of alumina and silver are mixed at different concentrations, namely 0.5%, 1% and 2% (m/m). The effect of the shape of the nanoparticles is also considered. These nanofluids are sprayed using a pressure-swirl atomizer and impact, vertically at two different heights, onto an AISI 304 stainless steel foil. This foil is heated by Joule effect, with two imposed currents, delivering 915 and 2100 W/m2. Infrared thermography is used to measure the thermal footprint from which the dissipated heat flux is calculated. Results show that, in steady state operation, the lowest surface temperature is obtained with the 0.5% (m/m) alumina nanofluid, while increasing alumina nanoparticles, concentration increases the radial temperature distributions on the surface. Results also show a mild effect of the shape of the nanoparticles. Hence, lowest surface foil temperatures are achieved with the silver nanofluid with spherical particles, when compared with the same nanofluid with triangular particles. Heat transfer coefficients decreased with increasing thermal conductivity and dynamic viscosity of the nanofluids. On the other hand, a positive correlation is found between the specific heat capacity of the nanofluids and the spray cooling capacity. For the range of experimental conditions covered in this work, nanofluids have proven to increase the thermal performance of the spray.

Effect of Surface Treatment of Stainless Steel Foils in High‐Performance Aqueous Zinc‐Ion Battery

Stainless steel foil, as the most commonly used current collector of aqueous zinc‐ion battery cathode, has the advantages of low cost, good conductivity, good flexibility, lightweight, and so on. However, as a current collector, stainless steel foil still faces a series of challenges, such as easy shedding of active materials and large contact resistance. In this work, the surface of stainless steel foil is modified by physical grinding and chemical etching, and the influence of surface morphology of stainless steel foil on battery performance is investigated. The results show that the stainless steel foil treated with 0.2 m FeCl3 + 0.1 m HCl etching solution for 1 min has the best electrochemical performance, and its maximum discharge specific capacity is 2.14 times that of the original stainless steel foil. In addition, the assembled Zn–MnO2 battery has good cycle stability and excellent rate performance, which can be attributed to the moderate roughness, effective contact area, and excellent conductivity of the modified stainless steel foil current collector.

Generalized semi-mechanistic model of impinging jet quenching heat transfer

In the present analysis, a semi-mechanistic maximum heat flux (qmhf) model has been developed for sub-cooled jet impingement cooling of the heated surface. The model for evaporative heat flux is based on the work of Katto's Model of Helmholtz instability theory of liquid thin film. While the convective heat transfer is derived from the model of bubble-induced turbulent heat transfer using integral analysis. Subsequently, the semi-mechanistic model of maximum heat flux is developed utilizing the assumption of infinite thermal conductivity of heated surface. In addition, experiments were performed on a heated vertical stainless steel foil of 0.15 mm thickness (SS-304) by circular horizontal impinging jets. Number of experimental parameters were studied including, initial surface temperature, nozzle to plate distance, flow rate, and effect of additives like surfactants and nanofluids. Finally, a generalized model for the maximum heat flux of sub-cooled jet is presented by incorporated different empirical parameters into the model using regression analysis with test data. Various modeling parameters are identified in the present investigation and comparisons of the present model with present tests data and previous findings are presented.

High-throughput nuclear resonance time domain interferometry using annular slits.

Nuclear resonance time domain interferometry (NR-TDI) is used to study the slow dynamics of liquids (that do not require Mössbauer isotopes) at atomic and molecular length scales. Here the TDI method of using a stationary two-line magnetized 57Fe foil as a source and a stationary single-line stainless steel foil analyzer is employed. The new technique of adding an annular slit in front of a single silicon avalanche photodiode detector enables a wide range of momentum transfers (1 to 100 nm-1 by varying the distance between the annular slits and sample) with a high count rate of up to 160 Hz with a Δq resolution of ±1.7 nm-1 at q = 14 nm-1. The sensitivity of this method in determining relaxation times is quantified and discussed. The Kohlrausch-Williams-Watts (KWW) model was used to extract relaxation times for glycerol. These relaxation times give insight into the dynamics of the electron density fluctuations of glycerol as a function of temperature and momentum transfers.

Enhanced fireproof performance of construction coatings by adding hexagonal boron nitride nanosheets

Hexagonal boron nitride (h-BN), commonly called “white graphene”, has received considerable attention thanks to its unique properties such as superior mechanical stability, high thermal conductivity, and exceptional chemical durability. Significant prior works have been dedicated for functionalizing the h-BN nanosheets for improving their optical, electrochemical, and biochemical properties. However, the application of h-BN sheets for the fire retardancy and thermal management of construction coatings has yet to be explored. In this work, we have investigated the thermal resistance and fire retardancy of the composite thin films composed of functionalized h-BN nanosheets deposited on stainless steel foils and fabrics. An efficient three-dimensional ball milling method is employed to synthesize the h-BN nanosheets with oxygen functionalities. We have shown that the h-BN-nanosheet-filled conformal coatings (including gypsum and sodium metasilicate) significantly enhance the fire retardancy of construction buildings. Uniform and homogeneous dispersity of the functionalized h-BN nanoparticles within the construction coatings has been verified by the scanning electron microscopy. Thermogravimetric analysis confirmed that the thermal resistance of the h-BN-filled coating is significantly enhanced with ultra-high thermal resistivity at 700 °C. Indeed, the addition of h-BN nanosheets improves the thermal shielding as well as the fire retardancy of the construction coatings, while serving as an efficient thermal insulating barrier. The robust design of h-BN-filled coatings demonstrated in this work paves the way for preparing green (i.e., environmentally friendly) construction materials.

Screen-Printing of Functionalized MWCNT-PEDOT:PSS Based Solutions on Bendable Substrate for Ammonia Gas Sensing.

Multi-walled carbon nanotubes (MWCNTs) were grown on a stainless-steel foil by thermal chemical vapor deposition (CVD) process. The MWCNTs were functionalized with carboxylic groups (COOH) on their surfaces by using oxidation and acid (3:1 H2SO4/HNO3) treatments for improving the solubility property of them in the solvent. The functionalized MWCNTs (f-MWCNTs) were conducted to prepare the solution by continuous stir in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), dimethyl sulfoxide (DMSO), ethylene glycol (EG) and Triton X-100. The solution was deposited onto a bendable substrate such as polyethylene terephthalate (PET) with a fabricated silver interdigitated electrode for application in a room-temperature gas sensor. A homemade-doctor blade coater, an UNO R3 Arduino board and a L298N motor driver are presented as a suitable system for screen printing the solution onto the gas-sensing substrates. The different contents of f-MWCNTs embedded in PEDOT:PSS were compared in the gas response to ammonia (NH3), ethanol (C2H5OH), benzene (C6H6), and acetone (C3H6O) vapors. The results demonstrate that the 3.0% v/v of f-MWCNT solution dissolved in 87.8% v/v of PEDOT:PSS, 5.4% v/v of DMSO, 3.6% v/v of EG and 0.2% v/v of Triton X-100 shows the highest response to 80 ppm NH3. Finally, the reduction in the NH3 response under heavy substrate-bending is also discussed.

Water ice-cooled MgB2 coil made by wind and react process

A wind and react (W&R) coil of inner diameter 53 mm has been made from multi-core MgB2/Nb/CuNi wire manufactured by the internal magnesium diffusion (IMD) process. The W&R coil is wound from non-insulated rectangular wire of 1 mm2 with only 5 µm thick stainless steel foil used for interlayer insulation. The transport current performance of the coil and short wire samples was measured in a liquid He bath at external magnetic fields of 4.5–8.5 T and also in self-field conditions in sub-cooled water ice at temperatures between 33 K and 38 K. The presented MgB2 coil exhibits stable behavior at water ice cooling, and its high space factor allows a high current density of winding in comparison to the data from the already published MgB2 coils. The presented results demonstrate that MgB2 windings can be used safely in He-free conditions inside sub-cooled water ice, and this technique can be further optimized and used for future MgB2 coils.

Effect of Annealing Temperature on the Interfacial Microstructure and Bonding Strength of Cu/Al Clad Sheets with a Stainless Steel Interlayer.

To explore the influence of annealing temperatures on the interfacial structure and peeling strength of Cu/Al clad sheets with a 304 stainless steel foil interlayer, an intermediate annealing treatment was performed at temperatures of 450 °C, 550 °C, and 600 °C, separately. The experimental results indicate that the interfacial atomic diffusion is significantly enhanced by increasing the intermediate annealing temperature. The average peeling strength of the clad sheets annealed at 550 °C can reach 34.3 N/mm and the crack propagation is along the steel/Cu interface, Cu-Al intermetallic compounds layer, and Al matrix. However, after high-temperature annealing treatment (600 °C), the liquid phase is formed at the bonding interface and the clear Cu/steel/Al interface is replaced by the chaotic composite interfaces. The clad sheet broke completely in the unduly thick intermetallic compounds layer, resulting in a sharp decrease in the interfacial bonding strength.

Highly (00l)-textured BiFeO3 thick films integrated on stainless steel foils with an optimized piezoelectric performance

Piezoelectric BiFeO3 films were successfully prepared on 304 stainless steel (SS) foils via RF-magnetron sputtering at 450 °C. By adopting a LaNiO3/Pt/Ti tri-layer bottom electrode, a predominant (100)-orientation and a better crystalline morphology were achieved in the BiFeO3 film, resulting in better ferroelectric and dielectric properties targeted for piezoelectric applications than those directly grown on SS or LaNiO3/SS. These properties include a large remnant polarization (Pr~68 μC/cm2), a large coercive field (Ec~241 kV/cm) and a sizable self-bias (Ebi~ 158 kV/cm), as well as a low dielectric constant and a reduced dielectric loss (εr≤200 and tan δ ≤ 0.026 in 1 kHz-1 MHz). Based on this optimal BiFeO3-SS heterostructure, large converse and direct transverse piezoelectric coefficients |e31,f| ~ 1.7 C/m2 and 1.07 C/m2 were achieved in prototype piezoelectric actuator and energy harvester structures, respectively. These results suggest that BiFeO3-SS heterostructures have a great potential for applications in lead-free, metal-based piezoelectric micro-electro- mechanical systems (piezo-MEMS).

Plastic deformation mechanism transition with solute segregation and precipitation of 304 stainless steel foil induced by pulse current

Stainless steel ultra-thin strip has become a hotspot because of its high added economic value. Reducing the deformation resistance during rolling is an effective and economical way to break through the minimum thickness limit of foil strips. And the dynamic softening effect of electroplastic effect provides a possible solution. However, the influence mechanism of electric pulse on stainless steel foil needs to be fully explored. In this work, the effects of pulse current with various peak current densities on the mechanical properties and deformation mechanism of 304 stainless steel foil were investigated. Compared with the conventional tension, the flow stress and elongation of steel foil are reduced during electro-pulsing assisted (EA) tension. The current causes the stress-strain curve to fluctuate in a serrated manner. The above changes can be attributed to the promotion of dislocation slip and the solute precipitation induced by coupling effect of deformation and pulse current. Besides, the pulse current suppresses the transformation from austenite to martensite and promotes the dynamic recrystallization (DRX), leading to reduction of deformation resistance. However, the severe solute segregation forms hard and brittle CrC intermetallic compound, which enhances the grain boundary strengthening, worsens the grain boundary properties and induces the generation of crack sources, resulting in the drastic diminishment in the ductility and toughness of steel foil. But this phenomenon can be avoided by controlling the current density and the treatment time during the deformation process.

Nitrogen-Doped Nanoporous Anodic Stainless Steel Foils towards Flexible Supercapacitors.

In this work, we report the fabrication and enhanced supercapacitive performance of nitrogen-doped nanoporous stainless steel foils, which have been prepared by electrochemical anodization and subsequent thermal annealing in ammonia atmosphere. The nanoporous oxide layers are grown on type-304 stainless steel foil with optimal thickness ~11.9 μm. The N-doped sample exhibits high average areal capacitance of 321.3 mF·cm−2 at a current density of 1.0 mA·cm−2, 3.6 times of increment compared with untreated one. Structural and electrochemical characterizations indicate that the significant enhancement is correlated to the high charge transfer efficiency from nitriding nanosheet products Fe3N. Our report here may provide new insight on the development of high-performance, low-cost and binder-free supercapacitor electrodes for flexible and portable electronic device applications with multiple anions.

Experimental demonstration of 7-femtosecond electron timing fluctuation in laser wakefield acceleration

We report on an experimental investigation of the jitter of electrons from laser wakefield acceleration. The relative arrival timings of the generated electron bunches were detected via electro-optic spatial decoding on the coherent transition radiation emitted when the electrons pass through a 100 μm thick stainless steel foil. The standard deviation of electron timing was measured to be 7 fs at a position outside the plasma. Preliminary analysis suggested that the electron bunches might have durations of a few tens of femtoseconds. This research demonstrated the potential of laser wakefield acceleration for femtosecond pump–probe studies.

Crystal Plasticity Simulation of Yield Loci Evolution of SUS304 Foil.

The deformation process of metal foils is usually under a complex stress status, and the size effect has an obvious influence on the microforming process. To study the effect of grain orientation and grain size distribution on the yield loci evolution of SUS304 stainless steel foils, three representative volume element (RVE) models were built based on the open source tools NEPER and MTEX. In addition, the yield loci with different grain sizes are obtained by simulation with Duisseldorf Advanced Material Simulation Kit (DAMASK) under different proportional loading conditions. The initial yield loci show a remarkable difference in shape and size, mainly caused by the distinct texture characteristics. By comparing the crystal plasticity simulation with the experimental results, the model with normal grain size distribution and initial texture based on Electron Back-scattered Diffraction (EBSD) data can more accurately describe the influence of the size effect on the shape and size of yield loci, which is the result of the interaction of grain size distribution and texture. However, the enhancement of grain deformation coordination will weaken the impact of the size effect on yield loci shape if the grain size distribution is more uniform.

Large‐area, high‐temperature stainless steel foil substrate for manufacturing low‐cost and flexible CMOS polysilicon TFTs

AbstractA large‐area stainless steel foil substrate which is compatible with high‐temperature (&gt;800°C) processing was developed to support a hybrid printed and conventional process technology to fabricate polysilicon thin‐film transistors (TFTs). The purpose was to build a platform that could lead to low‐cost, roll‐to‐roll manufacturing of polysilicon TFTs. To fabricate a self‐aligned top‐gate TFT structure, a screen‐printed dopant process, which requires high‐temperature activation, was developed to substitute capital‐intensive ion implantation. For the pilot line process, a 300‐mm2 and 100‐μm‐thick stainless steel substrate made of an alloy with a low thermal expansion coefficient (CTE) was chosen. Then, the foil finishing process was optimized to achieve flatness and minimize surface roughness. A barrier and dielectric encapsulation were developed to prevent trace metal diffusion from the substrate into the active layers. The polysilicon TFTs were then evaluated with static and dynamic bending tests.

Adhesive-Free Adhesion between Plasma-Treated Glass-Cloth-Containing Polytetrafluoroethylene (GC-PTFE) and Stainless Steel: Comparison between GC-PTFE and Pure PTFE.

In this study, the effect of plasma treatment on glass-cloth-containing polytetrafluoroethylene (GC–PTFE) was investigated. Previous plasma studies investigated pure PTFE (which does not contain glass cloth) but not GC–PTFE. The effect of Ar + H2O plasma treatment on GC–PTFE was investigated. The Ar + H2O plasma-treated GC–PTFE sheets were thermally compressed to stainless steel (SUS304) foils without using adhesive, and the GC–PTFE/SUS304 adhesion strengths were measured using a 90° peel test. The adhesion strength increased with the increase in the plasma treatment time (0.8 and 1.0 N/mm at 20 s and 300 s, respectively). Thus, strong adhesion between GC–PTFE/SUS304 was achieved without adhesive. This improvement in the adhesion properties of GC–PTFE can be attributed to the generation of oxygen-containing functional groups and the decrease in the surface roughness of the samples. Thereafter, the adhesion properties of GC–PTFE and pure PTFE were compared. Because, unlike pure PTFE, GC–PTFE has no weak boundary layer, GC–PTFE exhibited better adhesion properties than pure PTFE under short plasma treatment times.