Resistive Layer Research Articles

Conducting LixPOy Interface Generated From Insulating Residual Lithium Compounds on LiNi0.8Mn0.1Co0.1O2 Surface Improves Cycle Life and Assists in Fast Cycling.

LiNi0.8Mn0.1Co0.1O2 (NMC811) is the most promising cathode material for future Li-ion batteries (LIBs). However, the bulk and surface structural instabilities retard its commercial success. Surface chemical instability toward exposure to moisture (H2O and CO2) leads to the formation of residual lithium compounds (RLCs: Li2CO3, LiOH) on the surface. The alkaline RLCs form a resistive layer on the surface of NMC811 by undergoing parasitic side reactions with electrolytes. Herein, an "Adverse-to-Beneficial" approach is proposed to eliminate RLCs by chemically transforming them into a LixPOy (Li3PO4 and LiPO3) interface. The interface protects the NMC811 surface from moisture attack and unwanted side reactions with electrolytes. It enhances the cycle life by retaining 70% of the initial capacity after 300 cycles at a 0.5C rate and 60% after 500 cycles, even at a 5C rate in a voltage window of 3.0-4.3V versus Li+/Li. The coexistence of two Li-conducting phases lowers the voltage polarization of the kinetically sluggish H1 → M phase transition to unlock fast cycling, reduces cationic disorder, improves coulombic efficiency, enhances ion diffusion kinetics, and minimizes particle crack formation after long-term cycling. Hence, the LixPOy interface yields multifaceted benefits in the storage, processing, and electrochemistry of NMC811.

The Effect of Heat Treatment on the Plasma Nitriding of Hot-rolled 17–7 PH Stainless Steel

17–7 PH stainless steel is a highly versatile material with a multitude of applications in a diverse range of fields, including aerospace, chemistry and petrochemistry, and medicine. The material’s exceptional mechanical properties and corrosion resistance render it the optimal selection for numerous components and instruments. Nevertheless, the surface properties of 17–7 PH stainless steel are inadequate for applications requiring high hardness and wear resistance in certain extreme environments. Due to its excellent mechanical properties and corrosion resistance, it can be utilized in the manufacturing of pharmaceutical equipment components. However, certain specialized environments still require surface nitriding treatment. Considering the complex heat treatment process required for this material, this paper reports a detailed study of the surface performance changes of 17–7 PH steel before and after ion nitriding following aging heat treatment. The study employs rolled 17–7 PH stainless steel as the subject material. The impact of heat treatment on plasma nitriding of stainless steel is investigated by comparing and analyzing the influence of martensite content and dislocation density within the martensite of the material prior to and following heat treatment on the hardness, thickness, and corrosion resistance of the nitrided layer on the surface of the steel after nitriding. The results demonstrate that 17–7 PH stainless steel, which does not undergo heat treatment, exhibits a high internal dislocation density, a high nitriding efficiency, and consequently, a high surface hardness. Following the application of a heat treatment, there is an increase in the martensite content of 17–7 PH stainless steel, a decrease in the dislocation content, and an increase in the matrix hardness.

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries. Herein, we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator. The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition, but also reduce the formation of dendrite during early deposition stage. Most importantly, under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current, the high ductility and robust puncture resistance (145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite. The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm−2 with a polarization voltage of only 29.3 mV. Additionally, the negative charged layer serves as a physical barrier blocking lithium polysulfide ions, effectively mitigating capacity attenuation. The improved cells achieved a capacity decay of only 0.042% per cycle after 700 cycles at 3 C, demonstrating effective suppression of dendrite growth and capacity attenuation, showing promising prospect.

Impact of pressure and temperature on the hydration resistance of rice

Crop soaking, a hydration process driven by diffusion, is essential for applications such as milling and germination. This study investigated the moisture absorption of rice kernels during soaking, considering factors like pressure and temperature. The experimental data were analyzed using the Peleg model to understand hydration kinetics, revealing a strong correlation between empirical and regression data, with determination coefficients mostly exceeding 0.99. The study also assessed soaking hydration resistance, identifying contributions from various rice layers, including the husk and bran. Moisture content increased gradually with soaking time, with higher temperatures enhancing absorption. Under normal pressure, white rice absorbed water faster than paddy and brown rice, with brown rice exhibiting higher hydration resistance. Interestingly, paddy rice soaked faster than brown rice under certain conditions due to the air layer between husk and bran, which was eliminated under vacuum or higher temperatures, though the water replacing the air remained unabsorbed. This study aggregated hydration resistance from each kernel to determine layer resistance and specific diffusivity of husk and bran.

Intestinal tissue response to Shiga toxin exposure.

These studies have cemented the need for complex cell culture models when studying host-pathogen interactions. Common animal models such as mice are resistant to E. coli O157:H7 infections and intestinal delivery of Stx2, while humans appear to be sensitive to both. It has been proposed that in humans, shiga toxin-producing E. coli-mediated intestinal damage destroys the intestinal barrier and allows basolateral access to Stx2. In mice, there is no epithelial damage; therefore, they are resistant to epithelial delivery of Stx2 while remaining sensitive to Stx2 injection. Our studies show that like mice, the human epithelial layer is quite resistant to Stx2, and it is the sensitivity of the mesenchymal cells that kills the epithelial cells. We have shown that Stx2 is transported through the intact epithelium without causing damage to the resistant epithelial layer. Understanding tissue interactions during infections is therefore critical in determining the effects of pathogens on human tissues.

Mitigation of Membrane Fouling in Membrane Bioreactors Using Granular and Powdered Activated Carbon: An Experimental Study

This experimental study explores the mitigation of membrane fouling in membrane bioreactors (MBRs) through the combined use of granular activated carbon (GAC) and powdered activated carbon (PAC). The research assesses the impact of these materials on the fouling resistance, critical flux, and permeate quality using various mixed liquor suspended solids concentrations and carbon dosages. The results indicate that the GAC-PAC combination significantly reduces the total filtration resistance, particularly the cake layer resistance, by 11.7% to 13.6% compared to setups without activated carbon or with the individual carbon types. The study also reveals that this combination decreased the fouling rate by 15% to 24% at critical flux steps, demonstrating substantial improvements in fouling mitigation and operational efficiency. Furthermore, the GAC-PAC combination, which produces an adsorption process, enhances the permeate quality, achieving the near-complete removal of organic matter, total nitrogen, and turbidity, with total phosphorus removal reaching 99%. These findings demonstrate that the combined use of GAC and PAC not only reduces membrane fouling but also improves the overall MBR performance, making it a viable strategy for enhancing the efficiency of wastewater treatment processes.

Studies on InZnMgO amorphous buffer layer for Cu(In,Ga)(S,Se)2 solar cell

This study explores the effectiveness of an amorphous buffer layer, specifically Indium Zinc Magnesium Oxide (IZMO), as an alternative buffer in Copper Indium Gallium Sulfide Selenide (CIGSSe) solar cells. The findings reveal a significant impact on efficiency through precise adjustment of the Mg/(In+Zn+Mg) ratio (MIZM) from 0 to 0.23. The bandgap exhibits a consistent increase with an ascending Mg/(In+Zn+Mg) ratio, transitioning from 3.42 eV to 3.63 eV for IZMO prepared with Ar and from 3.18 eV to 3.53 eV for IZMO prepared with an Ar+O2 gas mixture, respectively. This rise is attributed to the augmentation of the conduction band minimum (EC) of IZMO resulting from the addition of MgO. Moreover, an increase in the Mg/(In+Zn+Mg) ratio correlates with improved conversion efficiency, escalating from 6.31 % to 9.19 %. Notably, the open-circuit voltage experiences a rise from 0.430 V to 0.520 V. This is attributed to the heightened EC of IZMO due to MgO addition, which mitigates recombination between the light-absorbing layer and the buffer layer, consequently elevating the open circuit voltage. The addition of MgO also enhances the resistance of the buffer layer, contributing to an increase in shunt resistance and a subsequent decrease in leakage current. Conversely, IZMO introduced with O2 exhibits inferior performance akin to IZO, attributable to substantial sputter damage induced by O2 introduction.

Impact of PCLNPG Nanopolymeric Additive on the Surface and Structural Properties of PPSU Ultrafiltration Membranes for Enhanced Protein Rejection

This research explored the use of a partially cross-linked graft copolymer (PCLNPG) as an innovative nanopolymer pore-forming agent to enhance polyphenylsulfone (PPSU) membranes for protein separation applications. The study systematically examined the impact of incorporating PCLNPG at varying concentrations on the morphological and surface properties of PPSU membranes. A thorough characterization of the resulting PPSU-PCLNPG membranes was performed, focusing on changes in morphology, water affinity, porosity, pore size, and pore size distribution. The experimental findings demonstrated that the use of PCLNPG led to a significantly more porous structure, as confirmed by SEM analysis, with notable increases in porosity and pore size (nearly double). Additionally, the hydrophilicity of the PPSU membrane was remarkably enhanced. Performance evaluations revealed a substantial improvement in pure water flux, with the flux nearly tripling. The BSA retention was directly correlated with the concentration of the PCLNPG pore former for a loading range of 0.25–0.75 wt.%. The incorporation of PCLNPG also reduced the membrane fouling propensity by reducing both cake layer resistance (Rc) and pore plugging resistance (Rp). These results underscore the potential of PCLNPG-PPSU membranes for wastewater reclamation and nutrient recovery applications.

On increasing the crack resistance of reinforced concrete structures by introducing fiberglass nets into the protective layer of concrete

Under operating conditions, the protective layer of concrete undergoes significant internal and external influences that lead to the formation of cracks. To increase the reliability and durability of reinforced concrete structures, it is proposed to install fiberglass nets in the protective layer of concrete, which is most susceptible to various aggressive influences during the operation of structures. The purpose of this work was to study the effect of fiberglass nets on increasing the crack resistance of the protective layer of concrete. The forces in the stretched concrete and in the rods of the fiberglass mesh located in the protective layer of concrete are calculated theoretically and using the software package «LIRA-CAD 2016» for a strip of concrete reinforced with a fiberglass mesh. The relative movements of the nodes in concrete and in the grid are determined and the obtained values are compared. As a result of the study, it was found that with a short-term effect of the load, fiberglass nets in the protective layer of concrete do not significantly affect the formation of cracks, with a long-term effect of the load, the presence of fiberglass nets reduces the formation of cracks by up to 2%. After the formation of microcracks in concrete, including from shrinkage deformations, fiberglass nets significantly hinder their further development.

Enhanced oxidation resistance and electrochemical performance of PEMFC gas diffusion layer through [EMIM][TFSI] ionic liquid coating

The performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) are critically hindered by the oxidation susceptibility of graphite felt gas diffusion layers (GDLs). This study addresses this challenge by employing a protective coating of 1-Ethyl-3-methylimidazolium Bis(trifluoromethyl sulfonyl)imide ([EMIM][TFSI]) on the GDL through a dip-coating method, followed by thermal curing to ensure uniform distribution and strong adherence. Comprehensive characterization, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier-Transform Infrared Spectroscopy (FTIR), confirmed the homogeneous coating, adhesion, and maintained porosity and gas diffusion properties of the GDL. The coated GDL exhibited a substantial increase in oxidation resistance, resulting in higher hydrophobicity with a contact angle of approximately 131°, compared to 96° for the uncoated GDL. Electrochemical analyses revealed that the [EMIM][TFSI]-coated GDL achieved a current density of 27 mA cm−2 at 0.925 V, surpassing the 19 mA cm−2 of the uncoated GDL at 0.91 V during cyclic voltammetry (CV) analysis. This study is limited by the short-term stability tests and the specific environmental conditions under which the experiments were conducted. Future work will focus on optimizing the coating process for varied environmental conditions and exploring the scalability of this technique for practical applications.

Geoelectrical Evaluation of Contamination in and around Ori-Ile Battery Wastes Dumpsite in Ibadan, Southwestern Nigeria

Geoelectrical surveys involving vertical electrical sounding (VES) and 2D resistivity imaging were integrated to assess subsurface contamination by heavy metals in and around Orile Battery Waste Dumpsite, Kumapayi in Ibadan, Southwestern Nigeria. The objectives are to determine the lateral and vertical variations of resistivity/conductivity in and around the dumpsite, determine the nature and thickness of the overburden, determine the depth to bedrock, and delineate subsurface zones of anomalously high conductivity/low resistivity which may have resulted from contamination by heavy metals. Thirty-three VES stations were occupied using the Schlumberger electrode array with electrode spacing (AB/2) varied from 1 m to 100 m. The 2D resistivity survey was carried out along six East–West trending traverses established across and around the dumpsite using the Dipole-Dipole electrode array with station spacing of 10 m and expansion factor, n=1-5. The VES data were quantitatively interpreted using initial partial curve matching technique and 1D forward modelling while the dipole-dipole data were interpreted using 2D inversion procedures. The geoelctric sections delineated three layers comprising topsoil with layer resistivity ranging from 18 Ωm to 264 Ωm and thickness varying from 0.4 m to 1.4 m, weathered layer with resistivity and thickness ranging from 1 Ωm to 219 Ωm and 0.6 m to 9.4 m respectively, and weathered/fractured/fresh bedrock with resistivity ranging from 132 Ωm and 6500 Ωm. The 2D inverted resistivity sections revealed anomalous resistivity lows suggesting contamination at depths ranging from 5 m to 10 m beneath the traverses. The contamination zones are characterized by resistivity values less than 10 Ωm. The study revealed that the soil beneath the study area has been contaminated by the battery wastes. The suspected fractures and relatively shallow water table observed in the study area may have predisposed the groundwater to contamination which could constitute serious health risk to the inhabitants. It is recommended that geochemical analysis for heavy metals be conducted on the soil and groundwater from wells in the study area to assess the level of contamination.

A practical method for the in-situ estimation of the effective thermal resistance of gas diffusion layers in PEMFC

The membrane electrode assembly of a PEM fuel cell is hotter than the gas feeding plates because heat is generated within it, and the diffusion layers are thermally resistive. The temperature gradient created, which increases as a function of the current density, is useful for evacuating the water produced in vapor form. This water transport mechanism is known as the “heat pipe effect”. The temperature gradient produces a saturation vapour pressure gradient, which in turn produces a diffusive vapor flow. Mastering water management, coupled with heat management, requires knowledge of the temperature of the MEA and therefore the effective thermal resistance of the diffusion layers. In this paper, we present an original method for estimating this thermal resistance in situ, without using heat flux sensors or directly measuring the temperature of the MEA. The method requires the ability to impose a temperature gradient between the anode and cathode plates, and to perform a hot-side water balance. Thermal resistance is deduced from the coupling between heat and water transfer. Two diffusion layers widely used by the community are tested. The GDL Sigracet 22 BB (from SGL Carbon) has a lower effective thermal resistance than the GDL Freudenberg H15C14. Variations in these thermal resistances are measured as a function of the temperature gradient imposed and of the compression ratio.

Effect of Cr3C2 on wear behavior of Ni45 laser cladding coating

Abstract To improve the performance of engineering components subjected to severe wear, temperature fluctuations, and corrosive conditions in industries such as chemical, aerospace, and power plants, Ni45-based coatings with varying Cr3C2 contents (0%, 10%, 20%, and 30%) were applied to a 45-steel surface. The microstructure of these coatings was examined by scanning electron microscopy (SEM), and their wear resistance was compared. As the Cr3C2 content in the cladding layer increased, there was a notable improvement in its wear resistance. Specifically, when the Cr3C2 content reached 30% by weight, the wear resistance of the cladding layer exceeded that of the GCr15 steel. Furthermore, the adhesive wear between the cladding layer and the GCr15 steel diminished, while the oxidation wear of the GCr15 steel intensified. This study aims to elucidate the primary wear mechanisms of the Cr3C2/Ni45 cladding layer and offer valuable insight into improving the durability of engineering components in harsh environments.

Effect of Electromagnetic Field Assistance on the Wear and Corrosion Resistance of Nickel-Based Coating by Laser Cladding

Offshore wind turbine generators usually demand higher requirements for key component materials because of the adverse working environment. Therefore, in this study, electromagnetic-assisted laser cladding technology was introduced to prepare the nickel-based composite coating on the Q345R matrix of wind turbine generator key component material. By means of Scanning Electron Microscope (SEM), X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), the Vickers hardness tester, friction and wear tester, and electrochemical workstation, the effects of different magnetic field intensities on the macroscopic morphology, microstructure, phase composition, microhardness, wear resistance, and corrosion resistance of the coating were analyzed. The experimental results show that the addition of a magnetic field can effectively reduce the surface defects, improve the surface morphology, and not change the phase composition of the coating. With the increase in magnetic field intensity, the microstructure is gradually refined, and the average microhardness increases gradually, reaching a maximum of 944HV0.5 at 8 T. The wear resistance gradually increases with the increase in magnetic field intensity, especially when the magnetic field intensity reaches 12 T, the wear rate of the coating is reduced by 81.13%, and the corrosion current density is reduced by 43.7% compared with the coating without a magnetic field. The addition of an electromagnetic field can enhance the wear resistance and corrosion resistance of the nickel-based laser cladding layer.

Electrochemical and corrosion behavior of steel rebars in concrete exposed to industrial SO2 and CO2 environment

Investigation into the corrosion mechanism of steel rebars in concrete under the combined influence of SO2 and CO2 is crucial for addressing the corrosion issues in reinforced concrete structures exposed to industrial environments. This study investigated the electrochemical and corrosion behavior of steel rebars in concrete under the combined influence of SO2 and CO2 using electrochemical methods, pH and SO42- concentration tests at the concrete/steel matrix interface, and surface analysis. During the corrosion process, a competitive chemical reaction between SO2 and CO2 occurs. The electrical resistance (Rc) of the concrete cover layer undergoes initial rapid growth, followed by slower increments, and then another period of rapid growth before eventually stabilizing. However, Rc sharply decreases over time, corrosion-induced damage in the concrete cover layer. CO2 diffuses to the vicinity of the rebar before SO2, inducing rebar depassivation. As rust severity increases, significant changes in the rust products are observed, with Fe(III) compounds transforming into Fe(II) compounds, and FeSO4·4H2O and FeSO4·7 H2O are prevalent in the rust products. Furthermore, the formation of ferrous sulfate compounds can lead to local acidification, thereby accelerating the corrosion rate, and hastening the aging and deterioration of the structure, posing a serious threat to the safety of the building structure.

Fabrication of Low Resistive and Adhesive Cu Layer on Glass Substrate by Chemical Bath Deposition and Chemical Reduction

Fabrication of Low Resistive and Adhesive Cu Layer on Glass Substrate by Chemical Bath Deposition and Chemical Reduction

Highly sensitive and chemically resistant moisture sensor based on polyether sulfone and polyimide composite membrane for power transformer oil

Abstract Moisture is the primary factor leading to the deterioration of transformer oil. Real-time detection of transformer oil moisture content holds significant importance to help power companies monitor the transformer’s operational status, track the change curve of the oil moisture content, identify water ingress causes, and implement preventive measures. However, transformer oil has the characteristics of low moisture content and complex chemical composition, which pose a substantial challenge for sensor monitoring, and require the prepared sensor to be chemically resistant and highly sensitive to moisture. To address these challenges, in this paper, a parallel plate oil moisture sensor with high sensitivity and high chemical resistance based on PES and PI was developed using the MEMS process. The sensor incorporates PES as the chemical resistance layer and PI as the moisture sensitivity layer. The parallel plate design not only optimizes sensitivity by effectively utilizing electric field lines but also allows the passage of water while isolating oil molecules, further enhancing the chemical resistance of the sensor. Experimental results in air demonstrate that the prototype sensor exhibits high sensitivity (~1.26 pF/% RH) across the full humidity range of 0-100% RH. Moreover, the sensor can withstand exposure to a wide range of chemical corrosive gases, including acetone, ammonia, etc. Tests in transformer oil reveal that the sensor has a resolution better than 200 ppm and can effectively measure moisture in the range of 0-1400 ppm, demonstrating very high sensitivity (4 pF/100 ppm) and rapid response (10/23 s).

Structural and phonon transport analysis of surface-activated bonded SiC-SiC homogenous interfaces

To avoid the interfacial thermal stress problem caused by high temperature, room temperature bonding techniques such as surface-activated bonding (SAB) are currently receiving widespread attention. However, the thermal boundary resistance (TBR) is challenging in reaching the theoretical value because the bombardment of the surface by energetic particle beams causes the formation of amorphous layers. In this paper, we have prepared SiC/SiC interfaces by surface-activated bonding and tried to explain the effect of the interfacial amorphous layer on the thermal properties. The results show that an amorphous layer of about 9 nm was formed at the SiC/SiC interface, mainly composed of carbon atoms. Molecular dynamics simulations derive an effective thermal boundary resistance (TBReff) of 4.78 m2K/GW for this interface, where the TBR of SiC/a-C is only approximately 0.50 m2K/GW. The TBReff with 30 % Fe after modification increased to 6.74 m2K/GW. The lower TBR between SiC/a-C can be attributed to coupling extended modes (EMs) and localized modes (LMs) at the interface and acting as a phonon bridge. In addition, the bulk thermal resistance of the amorphous layer accounts for 79.3 % of the TBReff. Besides, the molecular dynamics results show that the decrease in the thickness of the amorphous layer can significantly reduce the TBReff. As the thickness of the amorphous layer tends to zero, the TBReff is almost close to zero. The above conclusions will be beneficial to understanding the main factors influencing the thermal properties in the SiC/SiC interface, which point out the way for the subsequent improvement of the interfacial thermal conductivity.

Memristive gas sensor (gasistor) based on Ag/ordered TiO2 nanorods/FTO sandwich structure for evaluation of ethanol concentration in mixed ambient

Herein, we designed a memoristor-type gas sensor (gasistor) with Ag/ordered TiO2 nanorods/FTO sandwich structure for recognizing ethanol concentration in ethanol-methanol mixtures. The gas adsorption characteristics of different TiO2 substrates were first investigated by first-principle calculations. The results showed that the TiO2 surface in the low resistance state exhibited better immunity to other interfering gas molecules. However, similar adsorption energies and charge transfers calculated for adsorption of methanol and ethanol mean that the interference of methanol to the response of ethanol cannot be completely ignored. In next experiments, the Ag/TiO2/FTO gasistor with well-aligned TiO2 nanorods as the resistive layer was constructed successfully and demonstrated the stable resistive switching function and excellent retention characteristic. Further device tests confirm the ability of the gasistor in the low resistance state to discriminate between ethanol and methanol, as well as better anti-interference for other organic vapors. Also, an ultra-short recovery time (∼1.8 s) was observed by applying a direct current scanning voltage to the gasistor. Finally, to improve the recognition rate of ethanol in ethanol-methanol mixed atmosphere, a neural network algorithm based on back-propagation was incorporated and good prediction accuracy was obtained at ethanol concentrations ≥ 5 ppm.

Effect of oscillating laser cladding on microstructure and properties of stainless steel cladding layers

The laser cladding process is general accompanied by defects such as pores, cracks and uneven microstructure. In order to overcome the above defects, this study introduces the oscillating laser cladding technology, and uses oscillating laser cladding and without-oscillating laser cladding process to manufacturing the stainless steel cladding layers. The microstructure was characterized by XRD, SEM and EDS, and the microhardness, wear resistance and corrosion resistance of the cladding layer were analyzed by using vickers hardness tester, wear tester and electrochemical workstation. The results show that the oscillating laser cladding can have a great effect on the morphology and microstructure of the stainless cladding layer. Among the two cladding process, oscillating laser cladding can prepare a cladding layer with better properties. The grains in the oscillating laser cladding layer are obviously equiaxed, and the grain size is significantly smaller than that of without-oscillating laser cladding layers. In addition, the wear resistance and hardness of the oscillating laser cladding layer are higher than that of the without-oscillating laser cladding layer, but its corrosion resistance is slightly lower than that of the without-oscillating laser cladding layer.