Strip Interface Research Articles

Ultrahigh Areal Capacity Li Electrodeposition at Metal-Solid Electrolyte Interfaces under Minimal Stack Pressures Enabled by Interfacial Na-K Liquids.

The need for higher energy density rechargeable batteries has generated interest in metallic electrodes paired with solid electrolytes. However, impedance growth at the Li metal-solid electrolyte interface due to void formation during cycling at practical current densities and areal capacities, e.g., greater than 0.5 mA cm-2 and 1.5 mAh cm-2 respectively, remains a significant barrier. Here, we show that introducing a wetting interfacial film of Na-K liquid between the Li metal and the Li6.75La3Zr1.75Ta0.25O12 (LLZTO) solid electrolyte permits reversible stripping and plating of up to 150 μm of Li (30 mAh cm-2), approximately 10 times the areal capacity of today's lithium-ion batteries, at current densities above 0.5 mA cm-2 and stack pressures below 75 kPa, all with minimal changes in cell impedance. We further show that this increase in the accessible areal capacity at high stripping current densities is due to the presence of Na-K liquid at the Li stripping interface; this performance improvement is not enabled in the absence of the Na-K liquid. This design approach holds promise for overcoming interfacial stability issues that have heretofore limited the performance of solid-state metal batteries.

Patterning alternate TiO2 and Cu2O strips on a conductive substrate as film photocatalyst for Z-scheme photocatalytic water splitting

Semiconductor heterostructures mediated by electrical conductors are very promising for Z-scheme photocatalytic water splitting. In contrast to conventional particulate heterostructures, alternate TiO2 and Cu2O film stripes patterned parallel on a fluorine-doped tin oxide (FTO) conductive substrate was fabricated as a model film photocatalyst to study the characteristics of the photogenerated charge transfer process. The Z-scheme transfer process with an effective transport distance of up to 5 μm occurs only in regions distant from the TiO2/Cu2O strip edges through the FTO substrate from the bottom. In contrast, the transfer of charge around their contact regions follows the conventional transfer process through the TiO2/Cu2O strip interface. These results indicate that the Z-scheme transfer process occurring in such a large region dominates the charge transfer processes in the TiO2/FTO/Cu2O pattern film heterostructure. Importantly, unlike the single component film, which is inactive for photocatalytic overall water splitting, the modified TiO2/Cu2O pattern film can induce photocatalytic overall water splitting at a stoichiometric H2/O2 ratio close to 2:1. These findings have significant implications in designing efficient heterostructures by employing a Z-scheme charge transfer process.

Non-linear analysis of one-way concrete slabs with carbon-fibre-reinforced polymer strips

Finite-element (FE) models of one-way spanning reinforced concrete slabs strengthened with carbon-fibre-reinforced polymer (CFRP) strips were constructed and analysed. The slabs, which had different-sized openings at different locations, were tested by the authors in a previous study. During the FE analysis, the effective failure modes were taken into account and the behaviour of the concrete–CFRP strip interface was modelled using a non-linear cohesive zone material model. The results of the FE analysis and experimental data were compared in terms of the ultimate load capacities of the slabs, load–displacement graphs, stress distributions and failure modes. The modelled results were found to be consistent with the experimental findings. The yield and ultimate shear force capacities, the yield and ultimate displacements and the yield stiffness of the slabs were calculated with average errors of 11.4%, 6.3%, 27.1%, 13.8% and 24.2%, respectively. After verification of the FE model, analyses of four additional slabs, not previously experimentally tested, were performed. An equation between the ultimate load capacity of a slab and opening size was developed based on the modelling results.

Parametric analysis of mixed lubrication characteristics in work zone of strip rolling

A theoretical model for mixed lubrication with more accurate contact length has been developed based on the average volume flow model and asperity flattening model, and the lubricant volume flow rate and outlet speed ratio are determined by integrating differential equations based on rolling parameters. The lubrication characteristics at the roll−strip interface with different surface roughness, rolling speed, reduction and lubricant viscosity are analyzed respectively. Additionally, the average volume flow rates of lubricant under different rolling conditions are calculated and used to explain the change rule of lubrication characteristics. The developed scheme is able to determine the total pressure, lubricant pressure, film thickness and real contact area at any point within the work zone. The prediction and analysis of mixed lubrication characteristics at the interface is meaningful to better control the surface quality and optimize the rolling process.

Experimental and numerical analysis pull-out strength of steel strip in foam concrete

The structural performance of a reinforced concrete is influenced by the properties of the reinforcing element and the concrete interface. Therefore, investigating the pull-out strength and bond stress vs. slip relationship between components of the reinforced concrete are very important. This paper presents a numerical method to study the pull-out behaviour of galvanised steel strips in aerated concrete. A local bond-slip relationship is determined using experimental and theoretical analyses and is then implemented to the finite element simulation through the user-defined subroutine of ABAQUS software. The effect of strip geometry and mechanical properties of the aerated concrete on the pull-out force is also investigated. Comparison between the experimental, theoretical and FE simulation results shows very good agreement. It was shown that a trilinear bond-slip model is suitable for the modelling of steel strip and concrete interface.

Microstructure and Phase Transformations Near the Bonding Zone of Al/Cu Clad Manufactured by Explosive Welding / Zmiany Mikrostrukturalne I Fazowe W Pobliżu Strefy Połączenia Układu Warstwowego Al/Cu Wytworzonego Technologią Zgrzewania Wybuchowego

The structure near the interface of bimetallic strips strongly influences their properties. In this work, the interfacial layers of explosively welded aluminium and copper plates were investigated by means of a scanning electron microscope (SEM), equipped with a high resolution system for local orientation measurements (SEMFEG/EBSD), and a transmission electron microscope (TEM), equipped with energy dispersive spectrometry (EDX) for the analysis of chemical composition changes. The SEMFEG/EBSD-based local orientation measurements in the areas close to the interface, in both sheets, revealed fine-grained layers characterized by the clearly marked tendency of the copper-type rolling texture formation. The texture was described by an increased density of the orientations near the {112}<111>, {123}<634>and {110}<112>positions. The internal microstructure of the intermetallic inclusion is mostly composed of dendrites. The electron diffractions and the TEM/EDX chemical composition measurements in the intermetallic inclusions revealed only crystalline phases, both equilibrium and ’metastable’. Additionally, no significant regularity in the phase distribution with respect to the parent sheets was observed.

Evaluation of diffusion and phase transformation at Ag/Al bimetal produced by cold roll welding

Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between Al and Ag, mating surfaces were specially prepared and various rolling thickness reductions were applied. The minimum critical thickness reduction to begin cold weld was specified as 70% which equals 0.1630 critical rolling shape factors. The bimetallic strips were treated by diffusion annealing at 400 °C and various annealing time. The Al/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases. The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan. A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time. Some δ phases were detected close to the interface after anneal treating for 3 h and δ phase was thicker and more continuous by increasing annealing time. The microhardness measurement showed that in spite of formation of δ phase due to diffusion annealing, the interface hardness was reduced.

New concept of friction sensor for strip rolling: Theoretical analysis

A new concept of sensor is proposed to measure friction at roll–strip interface during strip rolling. By measuring elastic strains inside the roll, it is possible to evaluate contact stresses at roll–strip interface using an inverse analysis, with the great advantage not to mark the strip with the sensor. Using simulations, this new sensor is designed and its ability to evaluate contact stresses is discussed as a function of rolling conditions: influences of roll thermal stresses, roll deflection, roll–strip contact length, distance of measurement points to roll surface on contact stress reconstruction by inverse analysis are characterised. Results show that this sensor could be used in various pilot hot and cold rolling conditions for friction evaluation. Next step of this work is a pilot rolling test of the sensor.

The effect of oxide scale of stainless steels on friction and surface roughness in hot rolling

Friction is one of the most significant physical phenomena influencing metal forming. The deformation or fracture of oxide scale significantly affects the roll–strip interface behaviour. Sticking occurs frequently during hot rolling of stainless steels especially ferritic stainless steels, which causes surface defects of both steel products and rolls. It is important to characterize the features of the oxide scale in hot rolling of stainless steel strips, but few studies have been carried out. This paper focuses on the deformation of oxide scale and roll–strip interface characteristics in hot rolling of austenitic stainless steel 304L and ferritic stainless steel 430. Oxidation tests in a short time in humid air with water vapour content of 7.0 vol.% were carried out using Gleeble 3500 thermo-mechanical simulator, and the oxidation characteristics of 304L and 430 steels were obtained. The deformation, surface morphology of oxide scale of the steels, and the friction in hot rolling were studied in hot rolling tests. Thick oxide scale of 304L steel shows high lubricative effect while the breaking of thin oxide scales of 430 steel may make the steel substrate to contact with the roll, which counteracts the lubricative effect of the oxide scale and results in friction coefficient increasing with an increase of reduction. A FEM simulation has been developed to analyse the deformation behaviour of oxide scale and surface roughness transfer during hot rolling of stainless steels and the model describing the rough surface profiles of the scales and steel has been integrated into the simulation.

Adhesive tool wear in the cold roll forming process

Tool wear manifests in change of roughness of roll surfaces and governs the surface quality of both coated and uncoated products. Decrease of friction and wear in the roll–strip interface will stabilize the performance of the cold roll forming (CRF) mill and ensure uniform process output. The scope of this paper includes an experimental study of adhesive wear of hardened tool steel blocks sliding against a mild steel wheel and field observation of tool wear in the CRF of zinc coated mild steel. Wear mechanisms are identified for the materials interacting during the CRF process. The results include an empirical value of tool wear coefficient for D2 steel sliding against unlubricated uncoated hot rolled AISI C1020 mild steel.

Nonlinear finite element analysis of effective CFRP bonding length and strain distribution along concrete-CFRP interface

CFRP has been widely used for strengthening reinforced concrete members in last decade. The strain transfer mechanism from concrete face to CFRP is a key factor for rigidity, ductility, energy dissipation and failure modes of concrete members. For these reasons, determination of the effective CFRP bonding length is the most crucial step to achieve effective and economical strengthening. In this paper, generalizations are made on effective bonding length by increasing the amount of test data. For this purpose, ANSYS software is employed, and an experimentally verified nonlinear finite element model is prepared. Special contact elements are utilized along the concrete-CFRP strip interface for investigating stress distribution, load-displacement behavior, and effective bonding length. Then results are compared with the experimental results. The finite element model found consistent results with the experimental findings.

Study on the oxidation of stainless steels 304 and 304L in humid air and the friction during hot rolling

In rolling process, the contact friction is of crucial importance for accurate modeling, optimum design and control of industrial rolling processes. It is important to characterize the features of the oxide scale of stainless steel in hot strip rolling because the scale on the strip surface affects friction coefficient and thermal conductivity coefficient. To some extent, the rolling force and friction condition depend on the thickness and the microstructure of the oxide scale. Oxidation tests of stainless steels 304 and 304L were carried out in a high temperature electric resistance furnace. The humid air in which the water vapour content can be controlled was generated and remained to flow into the chamber of the furnace in 2.5×10−4m3/s to study the effect of humidity on the oxidation of stainless steels. The microstructure and thickness of oxide scale layer of stainless steels were obtained and two or three oxide layers can be found. The humid air has a significant effect on the growth of oxide scale. Hot rolling tests were carried out on Hille 100 rolling mill. The friction condition at the roll–strip interface during hot rolling of stainless steel was determined and the transfer of surface roughness was discussed.

Mobile Carrier Properties of N2O2- and N3O2-Type Schiff Base Molecules Towards Copper(II) Ions

Mobile carrier properties of two schiff base ligands, named bis(2-hydroxypropiophenone)-1,2-propanediimine (N2O2) and bis(1'-hydroxy-2'-acetonaphthone)-2,2'-diiminodiethylamine (N3O2), dissolved in dichloromethane for the extraction of copper(II) ions from an ammonium buffer feed phase into a nitric acid solution (receiving phase) were investigated and compared. The parameters influencing the transport efficiency such as pH of the feed phase, chemical composition of the receiving phase, carrier concentration in the membrane and time dependency of the process were studied and discussed. Addition of sodium dodecysulfate (SDS), an anionic surfactant, to the receiving phase enhances significantly the process efficiency. This reveals that the transport is controlled by the kinetics of decomplexation at the stripping interface. The transported amount of copper ions from ammonium buffer (pH 7) into the receiving phase including HNO3 and SDS across a dichloromethane layer containing N2O2 and N3O2, at 20 oC, was found to be 90.6 (±0.7) % and 97.4 (±0.4) % after 4 h, respectively. The selectivity of the processes towards copper ions were tested by performing the competitive transport experiments on the mixture containing Pb2+, Ni2+, Cd2+, Zn2+ and Co2+ ions. Although N3O2 possess higher transport efficiency with respect to that of N2O2, both ligands present adequate selectivity for separation of Cu(II) ions.

Performance of some extractants used for ‘actinide partitioning’ in a comparative hollow fibre supported liquid membrane transport study using simulated high level nuclear waste

The performance of different extractants used for ‘actinide partitioning’, viz. TRUEX, DIAMEX and TODGA is compared in hollow fibre supported liquid membrane (HFSLM) technique for the separation of trivalent lanthanides/actinides from simulated high level waste solutions. In the case of TODGA solvent (0.1 M TODGA + 0.5 M DHOA), quantitative transport of Nd(III) and Am(III) was achieved in 30 min from 500 mL of feed solution containing 0.6 g/L Nd at 3 M HNO 3 as well as from pressurized heavy water reactor-simulated high level waste (PHWR-SHLW). In the case of TRUEX solvent (comprising of 0.2 M CMPO as the extractant + 1.2 M TBP as the modifier in normal paraffin hydrocarbon), only 50% transport was observed which was attributed to the significant amount of acid transport, which in turn affected the dissociation of metal–ligand complex at the membrane–aqueous strip interface. However, quantitative transport of metal ions was even possible for TRUEX solvent after neutralization of feed acidity. On the other hand, DIAMEX solvent (1 M DMDBTDMA) resulted in about 85% transport under identical conditions which was explained on the basis of relatively lower D Am value under HLW conditions.

Analysis of interface temperature, forward slip and lubricant influence on friction and wear in cold rolling

To improve cold rolling processes, it is necessary to understand and to optimise contact at roll–strip interface. Thus a simulation test has been developed in our laboratory. The upsetting rolling test (URT) enables to study friction and iron fines pollution by the reproduction of the main industrial contact conditions such as plastic strain, normal and tangential stresses and forward slip. On the basis of the URT, a new experimental protocol has been developed to reproduce industrial lubrication regime. Moreover, a new heating system has been designed to simulate interface temperature which has a decisive effect on lubricant behaviour. These optimisations permit to analyse contact temperature, forward slip and lubricant influence on friction, iron fine pollution and surface aspects. A great influence of temperature and lubricant on friction and wear has been put forward. Actually an increase of the Coulomb friction coefficient associated with a decrease of the iron fines quantity have been shown with an increase of temperature. These results seem to indicate more adhesive wear when temperature increases.

Pertraction of lactic acid through supported liquid membranes containing phosphonium ionic liquid

Pertraction of lactic acid (LA) through supported liquid membranes (SLM) was investigated in a spiral channel flat sheet module using a liquid membrane with ionic liquid tetradecyl(trihexyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (IL-104) which is an effective extractant of LA. The increase in IL-104 concentration in n-dodecane from 0.32 to 0.72 kmol m −3 did not result in an increase of the overall mass-transfer coefficient of LA, although the distribution coefficient is directly proportional to the IL concentration. According to the analysis of mass-transfer resistances, this was caused by the increased viscosity of the liquid membrane and slower diffusion of the LAH–IL–H 2O complexes. Decreasing the LA concentration, the overall mass-transfer coefficient increased. This correlates well with the dependence of the distribution coefficient on the LA concentration. An increase in temperature from 25 to 35 °C increased the mass-transfer coefficient by about 50–70% although the distribution coefficient is independent of temperature. This was mainly due to the increased rate of decomposition of the LAH–IL–H 2O complexes on the stripping interface and only marginally to the moderate decrease of SLM viscosity. The back transport of water in the pertraction of LA through SLM with phosphonium IL was identified experimentally for the first time. The new mechanism of LA transport through SLM is suggested. The transport of LA is closely related to the back transport of water in the reverse micelles which are formed on the stripping interface. Depending on the LA concentration, about 14–8 mol of water are transported back per 1 mol of LA transported forward. The reverse micelles are split on the feed/SLM interface releasing water to the feed. SLM retained its stability and initial performance during the 5.3 days long experiment, which is promising.

A Transmission Line Method to Compute the Far-Field Radiation of Arbitrary Hertzian Dipoles in a Multilayer Structure Embedded With PEC Strip Interfaces

A transmission line (TL) method was proposed to compute the far-field radiation of Hertzian dipoles in a multilayer dielectric structure previously. This method is generalized here to deal with a structure embedded with perfectly electric conducting (PEC) strip interfaces. The problem is solved by analyzing an equivalent network, where each PEC strip interface is mapped into a four-port network, and each dielectric layer is mapped into two two-port networks for transverse electric (TE) and transverse magnetic (TM) modes. The S matrix of a four-port network is obtained analytically by applying the asymptotic boundary conditions. As an application, the PEC strip interfaces are used to reduce the cross polarization or rotate the polarization of a dielectric resonator antenna (DRA). In addition, the TL method is valid for a structure with any type of homogeneous and reciprocal layers whose S matrices are known. It is also able to solve two kinds of problems which cannot be done by a full-wave analysis equipped with a periodic boundary condition. Furthermore, the investigation of the system matrix singularity helps us to avoid the cavity mode in designing a radiating structure.

Mathematical modelling of unsteady-state transport of metal ions through supported liquid membrane

In this study, a mathematical model for unsteady-state transport of metal ions from aqueous solution through supported liquid membrane containing carrier is presented. For a transport process using supported liquid membrane, the three resistances to consider are the membrane resistance and the aqueous boundary layer resistances at the side of feed and stripping phases. The transport of species in the feed, the membrane and the stripping phases is modelled by Fick's second law. Time-dependent boundary conditions for the feed, the membrane and the stripping phases are obtained by means of kinetics of chemical reaction in the feed–membrane and the membrane–stripping interface. Partial differential equations obtained for the feed, the membrane and the stripping phases are analytically solved by using Duhamel's Theorem. Concentration distribution within the aqueous film layers and membrane as a function of position and time was derived from models obtained. The obtained model is checked against experimental data corresponding to the transport of copper ions from aqueous solution through supported liquid membrane by LIX 984.

Extraction and pertraction of phenol through bulk liquid membranes

AbstractThe extraction and pertraction of phenol through a bulk liquid membrane (BLM) with Cyanex® 923, Amberlite® LA‐2 and trioctylamine (TOA) as carriers were studied. Cyanex® 923 was selected as the best carrier for pertraction. The distribution coefficient of phenol for solvents with carrier and pure n‐alkanes, the individual mass‐transfer coefficient at the extraction interface and the initial flux of phenol through the extraction interface (JFo) decreased in the order: Cyanex® 923 > Amberlite® LA‐2 > TOA ≫ pure n‐alkanes. The opposite order was observed for the value of the mass‐transfer coefficient in BLM and the maximum flux of phenol through the stripping interface (JRmax). At constant driving forces the maximum fluxes through the extraction and stripping interfaces were similar when amine carriers were used. However, JRmax was lower than JFo for Cyanex® 923. Although the kinetics of stripping was the rate‐determining step, the flux of phenol was significantly higher than in pertraction with amine carriers. The adsorption of the carrier at aqueous phase/membrane interfaces was probably responsible for the rapid and slow transfer of phenol through the extraction and stripping interface, respectively. Copyright © 2004 Society of Chemical Industry

Asperity deformation, lubricant trapping and iron fines formation mechanism in cold rolling processes

Contact conditions in cold rolling are decisive to improve quality and final aspect of rolled strip. The control of contact conditions is obtained by a good combination of process parameters, such as normal and tensile force, forward slip and lubrication regime. To understand and to optimise contact at roll–strip interface, a simulation test was developed in our laboratory. The upsetting rolling test (URT) permits reproduction of the main contact conditions for cold rolling. The URT is able to simulate and to define the influence of rolling parameters on the iron residue quantities, and on the quality of the final surface. In accordance with finite element simulations, we can estimate a mean Coulomb’s friction coefficient. A very good correlation was found between experimental and numerical results. A complementary finite element model has been developed to predict the local behaviour of surface asperities during cold rolling. In this simulation at local scale, the roughness and trapping of lubricant are introduced, in addition to the pressure force and forward slip. It has been found that forward slip and reduction ratio modify the plastic strain behaviour of asperity through pressure and shear force. Thus, we are able to define the quantity of iron residues, as a function of the local plastic strain and the plastic energy solutions.