Resistive Layer Research Articles

Ultra-wideband absorber based on multilayer lossy frequency selective surface

In this letter, a multilayer dielectric with a lossy frequency-selective surface (FSS) absorber is proposed, which is composed of three layers of resistive film-dielectric composite layer and a metal grounded plane. Particularly, each resistive film-dielectric composite layer consists of a polyethylene terephthalate (PET), polymethacrylimide foam (PMI), and resistive film layer. An equivalent circuit model is established to further understand the performance of the absorber based on the impedance matching approach and the transmission line theory. Experimental results reveal that the metamaterial absorber (MMA) covers -10 dB bandwidth of 1.96-21.8 GHz for normal incidence. Meanwhile, the absorption rate can retain more than 80% for both TE and TM polarizations within 55° incidence angles. Furthermore, the fractional bandwidth of the MMA is 167% and its thickness is only 0.108 ?L. The MMA has the characteristics of ultra-wideband, high absorption rate, and polarization stability, making it suitable for communication systems.

Optimization of In‐Reactor In Situ Activation Annealing Conditions for Tunnel Junction Layers in Multiquantum Shell GaN‐Based Devices

For realizing room‐temperature continuous‐wave operation in core–shell GaN nanowire‐based semiconductor lasers, certain device characteristics are required, namely, a low threshold current and low operating voltage. To reduce the operating voltage and inject current into the m‐plane multiquantum shell (MQS) active region, a new structure with a tunnel junction and embedded n‐GaN is proposed. One of the problems in this proposed device architecture is the high resistance at the tunnel junction layer due to hydrogen passivation in the insufficiently activated p‐GaN shell. In situ activation annealing and suppression of re‐passivation during subsequent growth are necessary to reduce the operating voltage. Herein, the time and temperature dependence of in situ activation annealing in a reactor to lower the resistance of tunnel junction layers grown on nanowires with nonpolar m‐planes is investigated. Subsequent n+‐GaN growth is implemented at 550 °C. As a result, the turn‐on voltage is observed to be dependent on the activation annealing time and temperature. The lowest turn‐on voltage is ≈5.4 V at an activation annealing time of 30 min and activation annealing temperature of 800 °C.

Lithium titanate synaptic device imitating lithium-ion battery structure

With the growing prevalence of neuromorphic computing algorithms, there is a growing need for electronic synaptic devices. In this study, using Li4+x Ti5O12 (LTO) as the resistive switching layer, C as the lithium ions storage layer, and Li1+x Al x Ti2−x (PO4)3 (LATP) as ions transmission layer, a synaptic device is designed with the structure of Pt/C/LATP/LTO/PtSi to imitate the lithium-ion battery. Variation of the thickness of the LATP layer in the LTO device is explored to show the impact on the device’s synaptic performance. With a LATP thickness of 100 nm, the LTO synaptic device exhibits a high potentiation/depression cyclic stability of over 50 cycles, improved potentiation/depression linearity and smoothness. The synaptic potentiation/depression is ascribed to migration of lithium ions from the LTO layer. A conductance relaxation characteristic of the device is explained by battery self-discharge phenomenon. The battery effect in the LTO device also led to generation of electromotive force. The study of battery-imitating LTO synaptic device offers new perspectives on the connection between battery and analog synaptic device.

Fractionation and refining of pectic oligosaccharides derived from onion skins through continuous feed diafiltration

In this work, a diafiltration-based process was investigated for the recovery of pectic oligosaccharides produced by subcritical water hydrolysis from onion skin waste. Four tubular ceramic membranes from 100 to 1 kDa were selected based on the molecular weight of the different galacturonic acid species present in the onion skin hydrolysate. All these membranes showed high selectivity towards pectic oligosaccharides, with low retention for free galacturonic acid, monosaccharides, organic acids, and other impurities. The 50 and 100 kDa membranes completely retained pectic oligosaccharides with a molecular weight exceeding 80 kDa, accounting for approximately 30 % of the initial pectic oligosaccharides in the hydrolysate. However, the purification rate was significantly slower using the 50 kDa membrane due to the increased cake layer resistance. Furthermore, it was examined a fractionation/purification cascade involving sequential diafiltration stages using 100, 10, and 1 kDa membranes at 25 °C, TMP = 1 bar, and a crossflow velocity of 1.5 m s−1. Approximately 87 % of the initial pectic oligosaccharides were successfully recovered and purified in the retentates, highlighting their potential for diverse applications due to their narrow molecular weight distribution, while phenolic compounds and other valuable low molecular weight molecules were recovered in the final permeate.

On the Development of a New Flexible Pressure Sensor

The rapid advancement of the Internet of Things (IoT) serves as a significant driving force behind the development of innovative sensors and actuators. This technological progression has created a substantial demand for new flexible pressure sensors, essential for a variety of applications ranging from wearable devices to smart home systems. In response to this growing need, our laboratory has developed a novel flexible pressure sensor, designed to offer an improved performance and adaptability. This study aims to present our newly developed sensor, detailing the comprehensive investigations we conducted to understand how different parameters affect its behaviour. Specifically, we examined the influence of the resistive layer thickness and the elastomeric substrate on the sensor’s performance. The resistive layer, a critical component of the sensor, directly impacts its sensitivity and accuracy. By experimenting with varying thicknesses, we aimed to identify the optimal configuration that maximizes sensor efficiency. Similarly, the elastomeric substrate, which provides the sensor’s flexibility, was scrutinized to determine how its properties affect the sensor’s overall functionality. Our findings highlight the delicate balance required between the resistive layer and the elastomeric substrate to achieve a sensor that is both highly sensitive and durable. This research contributes valuable insights into the design and optimization of flexible pressure sensors, paving the way for more advanced IoT applications.

Initial corrosion behavior of 10CrNi3MoV steel and Q235 steel in marine atmosphere

Exploring the corrosion behavior of materials in a marine atmosphere and studying their corrosion resistance mechanisms can provide a basis for developing new weathering steels. This paper primarily introduces the initial corrosion behavior and corrosion resistance mechanism of 10CrNi3MoV steel in a marine atmosphere and explores the effects of Ni on the corrosion resistance. The corrosion resistance of 10CrNi3MoV steel and Q235 steel was compared using the weight loss method. The results show that the corrosion rate of 10CrNi3MoV steel was approximately half that of Q235 steel. The rust layer morphology and elemental distribution of 10CrNi3MoV steel were observed via scanning electron microscopy and energy-dispersive X-ray spectroscopy. The composition of the rust layer was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy, and the protective effect of the rust layer was further tested using an electrochemical test. The reason why Fe2NiO4 is beneficial for improving the corrosion resistance of the rust layer was explained using the Vienna Ab initio Simulation Package. The results reveal that the morphology, composition, element distribution, and electrochemical properties of 10CrNi3MoV steel were considerably stronger than those of Q235 steel because of the formation of Fe2NiO4 in the rust layer. Fe2NiO4 refines the rust layer particles and promotes the transformation of corrosion products to α-FeOOH. In addition, it imparts ion selectivity to the rust layer, effectively blocking the invasion of Cl−.

A novel UV-curable amphiphobic coating with dynamic air-layer copolymer brush offering stable dual-functional anti-scaling and anti-corrosion properties

Scale deposition and metal corrosion, especially in the petroleum industry, have always been serious issues that seriously affect economic efficiency and safety. However, conventional anti-scaling strategies including mechanical descaling and chemical detergents are energy-consuming and environmentally damaging, which can't achieve efficient and long-term protection. Based on mechanical descaling and chemical detergents, and anti-corrosion strategies based on filler are inadequate to realize efficient protection. Herein, this work reports a novel UV-curable polymer coating with long-term anti-scaling and anti-corrosion properties. The excellent anti-scaling capability was achieved by inhibiting interfacial nucleation and reducing interfacial adhesion work of scaling products. Significantly, the anti-scaling capability of the designed coating mainly originates from two aspects: inhibiting interfacial nucleation and reducing interfacial adhesion work of scaling. Compared with pure polyurethane acrylic coating (0 % FGSS), the 20 % FGSS coating shows significantly improved scaling repellence even after a 240 h dynamic scaling test while maintaining a fairly low theoretical adhesion work (≈0.1 mN/m). This outstanding anti-corrosion capability of the FGSS coating mainly originates from two aspects: the physical barrier effect of the air layer and low surface energy resistance barriers with dynamic FGSS brushes. The physical barrier effect of the air layer and the low surface energy resistance barriers also lead to outstanding anti-corrosion property (with the |Z|0.01 Hz value maintained at 108 Ω·cm2). This study presents a simple and effective design and fabricated strategy, paving a new pathway for developing UV-cured coatings with unique anti-corrosion and anti-scaling properties. This facile and effective UV-curable polymer coating shows great potential in metal protection and paves a new pathway for the development of long-term functional protection coatings.

Development of Prefabricated Additional Insulation Elements for the Renovation of High-Rise Apartment Buildings

Prefabricated additional insulation elements have demonstrated success in renovating up to 5-storey apartment buildings. However, the unique challenges posed by high-rise buildings necessitate a closer examination of installation and long-term performance. In this study, we developed an additional insulation element specifically tailored for renovating high-rise apartment buildings and analysed its hygrothermal performance. To test the performance of the insulation elements, we installed a prototype and measured its performance at critical points along the external envelope. We calibrated a calculation model and applied building performance simulation software to explore various combinations of prefabricated elements. Our goal was to compare the associated risks and the key hygrothermal properties of these different material combinations within the insulation element. Critical points between the insulation layer and the wind barrier, as well as between the surface of the existing concrete panel wall and the vapour control layer of the additionally insulated exterior wall were analysed. The study's results indicate that the thermal resistance and water vapour permeability of the wind barrier layer, and the presence of an appropriate vapour control layer primarily influence the performance and moisture dry-out of a structure. Additionally, the study results indicate that the weather component has a higher impact than in lower buildings as the wind-driven rain loads are considerably higher in the upper parts of the high-rise buildings. The initial moisture (w = 110 kg/m3 at the height of the 9th storey and w = 117 kg/m3 at the height of the 16th storey) dry-out can last more than 3 years depending on the building type and materials used. This study underscores the importance of tailored solutions and vigilant moisture safety management in high-rise apartment building renovations, particularly when utilizing prefabricated additional insulation elements.

EFFECT OF DIFFERENT UV EXPOSURE ENERGY ON POLYIMIDE-BASED NONVOLATILE RESISTIVE PHOTOMEMORY DEVICE

Recently, many researchers pay attractive attention to organic memory technology. Polyimide film was used as the resistive switching layer of nonvolatile photomemory in this study. In order to improve the performance of the device, different wavelengths of Ultraviolet (UV) light were used to operate the device, and its impact on the polyimide film was discussed. In this paper, three different UV light bands, UVA, UVB, and UVC, are used to switch devices between low resistance state (LRS) and high resistance state (HRS). It can be seen from the results that all three kinds of energies of UV light can transform the polyimide film from HRS to LRS successfully. According to the data, after 1s of UVB irradiation, the LRS current of polyimide-based photomemory device is the largest, and the data retention ability is also the best, the second is to irradiate UVA, and the last is to irradiate UVC. The results of the optical properties and electrical properties are coincidental. Therefore, different UV energies can affect this photomemory device.

Direct high-temperature growth of GaN on Si using trimethylaluminum preflow enabling vertically-conducting heterostructures

Abstract In this work, we demonstrate that GaN can be directly grown at high temperature on Si(111) substrates by metalorganic chemical vapor deposition without using any intentional AlN buffer, by simply employing a trimethylaluminum (TMAl) preflow. We found that n-GaN layers directly grown on n-Si with a TMAl preflow not only present a better crystalline quality compared to the use of thin AlN buffers, but also exhibit orders-of-magnitude improvement in vertical current conduction between GaN and Si, thanks to the absence of highly resistive AlN layers. Our proposed technique opens a new pathway for the effective realization of fully-vertical GaN-on-Si devices.

Highly Promising 2D/1D BP-C/CNT Bionic Opto-Olfactory Co-Sensory Artificial Synapses for Multisensory Integration.

The development of high-performance artificial synaptic neuromorphic devices poses a significant challenge in the creation of biomimetic sensing neural systems that seamlessly integrate both sensory and computational functionalities. In pursuit of this objective, promising bionic opto-olfactory co-sensory artificial synapse devices are constructed utilizing the BP-C/CNT (2D/1D) hybrid filter membrane as the resistive layer. Experimental results demonstrated that the devices seamlessly integrated the light modulation, gas detection, and biological synaptic functions into a single device while addressing the challenge with separating artificial synaptic devices from sensors. These devices offered the following advantages: 1) Simulating visual synapses, they can effectively replicate fundamental synaptic functions under both electrical and optical stimulation. 2) By emulating olfactory synapse responses to specific gases, they can achieve ultra-low detection limits and rapid identification of ethanol and acetone gases. 3) They enable photo-olfactory co-sensing simulations that mimic synaptic function under light-modulated pulse conditions in distinct gas environments, facilitating the study of synaptic learning rules and Pavlovian responses. This work provides a pioneering approach for exploring highly stable 2D BP-based optoelectronics and advancing the development of biomimetic neural systems.

Controlling the composition and nanostructure of Au@Ag–Pt core@multi-shell nanoparticles prepared by co-reduction method

Three types of Au@Ag–Pt core@multi-shell nanoparticles (NPs) were synthesized via a co-reduction reaction from a galvanic replacement reaction (GRR) and a reducing agent, with different feeding ratios of Ag or Pt precursors. The morphology of the core-shell NPs showed a thin multi-shell with a mixture of Ag, void, and Pt granules, and their microstructure was investigated by scanning transmission electron microscopy. The effect of the Ag or Pt precursor feeding ratios on the competition of the two reduction reactions, and the subsequent impact on the nanostructure of Ag-void-Pt multi-shell were discussed. In the case of the sample with a reduced Ag precursor feeding ratio, the thickness of the Ag layer decreased significantly. The oxidation resistance of the Ag layer was improved due to the charge-transfer effect from Au to Ag, which suppressed galvanic replacement, and the reaction by the reducing agent was dominant. In the case of the sample with a reduced Pt precursor feeding ratio, the number of Pt granules was found to decrease while the volume of voids was maintained, suggesting that GRR was the dominant reaction in the co-reduction method. These results provide further insight into the co-reduction reaction mechanism and enable the control of noble trimetallic nanoparticles with complex shells.

A multi-layer model for double-skin Pd-based membranes: Layer-by-layer parameter fitting

The Pd-based double-skin (DS) membrane has high potential to be implemented in various industrial processes. However, its multi-layer structure makes it difficult to model and understand the limiting transport mechanisms through each of these layers. In this work an extensive set of experiments on several membranes with different configurations was performed with the purpose of deriving a detailed model for the double-skin Pd-based membrane. This is important for the general understanding of the mass-transport taking place within each of the membrane layers, namely the support, the selective and the protective layer. Characterization, permeation tests and data-fitting led to the construction and validation of a multi-layer model for the DS-membrane. The experimental results also pointed out that the protective layer of HT or YSZ/Al2O3 has only a minor or negligible effect on the overall transport resistance of the membrane. The influence of the support was found to be small but not negligible compared to the dominating resistance of the dense selective PdAg layer. Experiments and simulations of the membrane permeation in multi-component mixtures also highlighted the large importance of concentration polarization and H2 depletion, which were successfully described in the model using a film-layer model together with a Sherwood correlation.

Effect of Y2O3 Content on Microstructure and Wear Resistance of Laser Cladding Layer of Stellite-6 Alloy

Laser cladding technology is an effective surface modification technique. In order to prepare coating with excellent properties on the surface of the cold heading die punch, stellite-6 cladding coating with different proportions of Y2O3 was prepared on the surface of W6Mo5Cr4V2 high-speed steel using laser cladding technology in this paper. The effects of different Y2O3 contents on the macroscopic morphology, microstructure, phase analysis, microhardness, and tribological properties of the stellite-6 coatings were investigated. It was determined that the optimal Y2O3 content for the stellite-6 powder was 2%. The results showed that the coating with 2%Y2O3 had the least number of pores and cracks and exhibited good surface flatness when joined. The microstructure became finer and denser, composed mainly of branch, cellular, equiaxed, and columnar grains. The coating consisted mainly of γ-Co, Fe-Cr, and Co3Fe7 strengthening phases, indicating good metallurgical bonding between the coating and the substrate. The average microhardness reached 539 HV when 2%Y2O3 was added, a 15.2% increase compared with the unmodified multilayer coating. The friction coefficient of the clad layer was 0.356, a 21.8% improvement over the unmodified stellite-6 coating. The average worn area of the cross-section was 3398.35 μm2, a reduction of approximately 27.8% compared with the unmodified stellite-6 clad layer. The wear surface primarily exhibited abrasive wear, with fewer cavities and a smoother surface.

An experimental study on the quality of hardfacing layer through resistance seam welding

Shaft-shaped parts work normally in wear-resistant conditions. Over time, the shaft might experience wear and fail to maintain the required size, affecting its workability and efficacy. This study examines the hardfacing layer quality of a restored steel shaft obtained through resistance welding. The researchers of this study designed nine welding conditions according to Taguchi's experimental matrix and applied each to experimentally weld steel shaft samples. A recovery welding machine system, which includes a resistance seam welding machine combined with a designed fixture, was used to weld the samples. The experimental results revealed that the welding layers’ surface is flat and has no surface defects. Meanwhile, the hardfacing layer and the retorted shaft surface have good cohesion, as observed through macrostructure photography. The hardness and wear resistance of the hardfacing layer were relatively high and closely resembled those of a new high-frequency quenched steel shaft. The influence level and the relationship of the welding parameters on hardness and wear resistance were also considered in this study. In addition, this study proposes the appropriate welding conditions for obtaining the highest hardness and the smallest worn metal weight. The findings presented in this study offer valuable insights for mechanical manufacturers engaged in the reconditioning process of shafts, aiding in time and cost savings.

Chemically activated Ag-embedded bridged-layer for copper pattern addition on PET film

This article describes a chemically activated method for copper addition on polyethylene terephthalate (PET) films with robust reliability and easy process. Thereof, a bridging layer produced by compatible composite of inorganic AgNO3 and organic epoxy resin (ER) in propylene glycol methyl ether (PM) solvent, was coated on the PET. It was chemically activated when immersed in acetone reagent and sodium borohydride solution, and accordingly the AgNO3 was reduced into Ag monomers as copper catalysts in the next chemical deposition procedure. The as-catalyzed Ag dot is embedded in the bridging layer and thus weaken the interface incompatibility between organic bridging layer and the next deposited metal copper layer. In the chemical plating process, a copper thickness of about 1.5 μm was achieved after 45 min’s plating. Reliability tests that the plated samples were bended by 5000 times at 5-mm and 2-mm radius, were carried out. The results showed the copper layer's resistivity was 0.5 and 0.65 times increasing respectively, in comparison with its originated property and it therefore exhibits excellent fatigue resistance.

A comparative study of C, N and Xe pre-amorphization implantation processes for improving the thermal stability of NiSi films

In this paper, a comparative study of C-, N- and Xe-based pre-amorphization implantation (PAI) processes is proposed. The impact of the use of such processes on the agglomeration resistance and physical properties of the final Ni(Pt)Si layer, as well as the formation mechanisms via solid-state reactions and electrical performances via the transfer length measurement (TLM) method, is evaluated. It is shown that although all species are able to increase the agglomeration temperature of Ni(Pt)Si layers (up to more than 100 °C), the underlying mechanisms are different. For C- and N-based PAI processes a strong chemical effect is observed, while for Xe-based processes the amorphization depth plays an important role. Consequently, the beneficial effect of stabilizing Ni(Pt)Si layers at high temperatures using C- and N-based PAI processes has to be balanced with an increased layer resistivity (up to 30%) combined with a strong deterioration of the associated specific contact resistivity (which is multiplied by almost a factor 10). In this sense, Xe-based PAI processes seem to be a better option as they could allow to combine both requirements.

Delineation of aquifer storage potential in response to regional groundwater development

Developing aquifers as part of sustainability efforts toward groundwater development is a tactical approach to meeting water demand and management objectives. Delineation of aquifer storage potential (ASP) and longitudinal conductance (SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document}) is a good approach to protect and manage groundwater resources. A Schlumberger configuration was applied to delineate fifteen (15) vertical electrical sounding (VES) stations alongside a 2D electrical resistivity imagery (ERI) profile and regional borehole data to characterize the regional ASP. The results of the study show that the layer resistivity and thickness values of the regional aquifer unit range from 39.9–105 Ωm and 15–44 m, respectively, while the overburden thickness overlays the regional aquifer unit varied between 5–10 m corresponding to the regional borehole data. The weathered/fractured basemen, which constitute the regional aquifer unit were delineated, which consists of shallow, moderate, and deep aquifer zones. The deep aquifer zones fall within the depth of 30–44 m and are considered suitable for groundwater prospective. The weathered layer with appreciably low resistivity values with thick aquifer regolith has also been identified as most suitable for borehole siting. The weathered/fractured encountered within thick aquifer regolith were mapped as the region with a high ASP for groundwater development. In addition, the values of longitudinal conductance, SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document} and transverse resistance, RT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}_{T}$$\\end{document} estimated from aquifer parameters vary between 0.21-0.85Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.21-0.85 \\,{\\Omega }^{-1}$$\\end{document} and 1695-3124Ωm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1695-3124\\, {\\Omega m}^{2}$$\\end{document}, respectively. The SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document} values show that the study area falls within moderate (0.20-0.69Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.20-0.69 \\,{\\Omega }^{-1}$$\\end{document}) and good (0.7-4.9Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.7-4.9 \\,{\\Omega }^{-1}$$\\end{document}), which invariably determined the regional aquifer protective capacity. Thus, the DC geoelectrical approach has been successfully employed in a lateritic-based environment to delineate aquifer-promising zones for regional groundwater development.

Quantitative analysis of the influence of PVA interlayer on the permeation resistance of TFC NF membranes

The interfacial polymerization based on the interlayer is an effective method for enhancing thin-film composite (TFC) nanofiltration (NF) membranes permeability. In this study, a polyvinyl alcohol (PVA) interlayer was constructed on a polyethersulfone substrate through a physical deposition method. Then the TFC NF membranes regulated by PVA interlayer were prepared, and conducted a quantitative analysis of the impact of the PVA interlayer on the permeation resistance of TFC NF membranes. The results indicated that after regulated by the PVA interlayer, the permeation resistance of the polyamide layer decreased slightly, from 0.130 to 0.106 bar h m−1, while the permeation resistance of the substrate decreased significantly, from 0.277 to 0.087 bar h m−1. These results indicated that the dramatic decrease in permeation resistance of substrate caused by PVA interlayer was main reason for enhanced permeability, enriching our understanding of the mechanism of the interlayer.

Improvement of corrosion resistance and electrical conductivity of a Cr–C coated heat-assisted forming stainless steel bipolar plate for proton exchange membrane fuel cell

Heat-assisted forming is gaining increasing attention for its potential in improving the formability and quality of metallic bipolar plate (BPP) of proton exchange membrane fuel cell (PEMFC). However, the effects of heat-assisted forming and the subsequent coating process on corrosion resistance and electrical conductivity of stainless steel BPP still remain unclear. This work proposes a way to improve simultaneously the corrosion resistance and electrical conductivity of heat-assisted forming stainless steel BPP by depositing a Cr–C coating directly on its surface without removing the oxide layer using the magnetron sputtering method. Potentiodynamic tests indicate that self-corrosion current density and corrosion current density at 1.0 V (vs. Ag/AgCl) of the Cr–C coated heat-assisted forming SS316L BPP prepared under 900 °C for 10 min are 0.021–0.040 μA cm−2 and 77.54 μA cm−2, respectively, both of which are smaller than those of coated SS316L BPP formed under room temperature. In addition, the contact resistance is close to that of the gold-plated copper plate under the same pressure. The corrosion resistant intermediate oxide layer and conductive network formed between Cr–C coating and metal substrate through defects of oxide layer may be the main reason for improvement of its corrosion resistance and electrical conductivity, respectively.