Resistive Layer Research Articles

Experimental investigation on the frost resistance of RCC layers with various interface treatments

This research investigates the influence of various interface treatment methods on the frost resistance performance of Roller Compacted Concrete (RCC) layers. Freeze-thaw cycle tests were conducted on RCC with interfaces treated using cement mortar, expansion agent mortar, and nano-SiO2 mortar. The study evaluated shear failure modes, shear strength, crack expansion, pore structure, and liquid uptake of the RCC interface after freeze-thaw cycles under different treatment methods. Results reveal that expansion agent mortar and nano-SiO2 mortar improve the shear strength of RCC after freeze-thaw cycles more effectively than cement mortar. The freeze-thaw cycles increase the width and expansion rate of cracks at the RCC interface during the shear process, while mortar treatments help delay crack development. Additionally, the pore volume at the RCC interface gradually increases, and the uniformity of pore distribution decreases under freeze-thaw cycles. During liquid uptake, mortar treatments slow down the upward migration of liquids by improving the pore structure at the interface. The liquid uptake of RCC exhibits a distinct linear relationship with its shear strength and pore structure. As liquid uptake time increases, water first fills larger pores before gradually entering smaller ones. Freeze-thaw cycles cause an increase in pore volume and enlargement, which leads to greater liquid uptake. Based on the damage mechanism of the RCC interface under freeze-thaw conditions, a model of shear strength degradation due to freeze-thaw cycles was established, aligning well with experimental results. Mechanism analysis indicates that nano-SiO2 and expansion agents enhance frost resistance by filling interface pores and cracks through reactions with certain compounds, thereby improving the microstructure.

Investigation of the microstructural characteristics of laser-cladded Ti6Al4V titanium alloy and its corrosion behavior in simulated body fluid

Laser cladding technology has a wide range of potential industrial applications in the surface strengthening, repair and reuse of orthopedic implants. By employing this technique to conduct same-material surface restoration and enhancement on titanium alloys, it demonstrates significant developmental potential. However, the microstructure of laser additively manufactured titanium alloy differs significantly from that of traditional titanium alloys, which affects its corrosion resistance in human body fluids. To compare the corrosion resistance differences between the cladding layer and the substrate, this study investigates the microstructure of multi-pass laser cladding Ti6Al4V (TC4) titanium alloy and analyzes the corrosion morphology and corrosion products of the cladding layer in simulated body fluids (SBF). By comparing the electrochemical corrosion behavior of laser cladding with that of traditionally manufactured TC4, this research reveals the differences in corrosion resistance between the two titanium alloys. The research demonstrates that the microstructure of cladding primarily consists of prior-β grains and continuous grain boundary α phase, along with a complex basketweave structure composed of fine acicular α phase and lamellar α phase. Additionally, due to the complex thermal cycling process, the acicular α' colonies within the prior-β grains. These features enhance the cladding layer’s resistance to plastic deformation and increase microhardness, though with some uneven distribution. Interestingly, the TC4 cladding layer forms a porous passivation layer after corrosion, primarily composed of a TiO2 passivation film and deposits of hydroxyapatite and other phosphates. Due to the lower β-phase content, finer grains with higher energy states, and a greater proportion of high-angle grain boundaries (HAGBs) in the cladding layer, it exhibits higher electrochemical activity. As a result of these microstructural differences, the corrosion resistance of the TC4 cladding layer in SBF is inferior to that of TC4 manufactured using traditional techniques.

Convolution Analysis in Electrodeposition

Convolution is a well established method for data analysis for electrochemical processes where both product and reactants are soluble. Advantages of convolution analysis include (a) facile evaluation of kinetic and system parameters, (b) ready corrections for nonfaradaic uncompensated resistance and double layer charging, (c) track of surface concentrations with time, independent of the voltage perturbation sequence, and (d) ease of convolution calculation from digitized current data. Here, equations are derived for convolution of electrodeposition data and a data analysis protocol is presented. Advantages are found for convolution analysis in electrodeposition. Parameters that can be determined from convolution analysis in electrodeposition are standard heterogeneous rate constant k 0 and exchange current density j 0, transfer coefficients α and β, formal potential E0′ , resistance to charge transfer, and diffusion coefficient of the solution soluble reactant D M . Convolution in electrodeposition is illustrated for silver deposited from an ionic liquid onto a glassy carbon electrode, where experimental data are tracked cyclic voltammetrically.

Supported g-C3N4/WO3 mixed layers for photocatalytic water remediation

g-C3N4 layers with good mechanical properties, including their cohesion and adhesion to stainless-steel supports, were prepared by the quantitative electrophoretic co-deposition of g-C3N4 and WO3 nanocrystals. It was carried out in a mixture of organic solvents by applying a voltage of 750 V. The typical layer area density was 0.64 mg cm–2. The photocatalytic degradation of 4-chlorophenol under blue-light irradiation showed that the performance of stable composite layers containing 25–50 wt.% of WO3 was only slightly weaker than that of unstable pristine g-C3N4 ones. The high photocatalytic performance was due to g-C3N4, while WO3 contributed to a good mechanical resistance of layers in stirred water. Finally, the composite layers exhibited a very high 4-chlorophenol mineralization of 75% in 24 h, even higher than the corresponding suspensions. Owing to their stability in water and performance, the developed layers are suitable for applications in environmental technologies.Graphic

Study on low temperature and narrow heating bands of post weld heat treatment for girth welds stress reduction of long-distance pipelines

Residual stress affects the service safety of pipelines, but there are few efficient methods to reduce the residual stress, especially for long-distance pipelines with large diameters. In this paper, a Secondary Post Weld Heat Treatment (S-PWHT) stress reduction method with low temperature and two narrow heating bands is proposed, and this method fully considers the failure of the corrosion resistance layer caused by high temperature. The temperature distribution and stress distribution under different S-PWHT parameters are compared to obtain the optimal S-PWHT parameters using finite element numerical simulation. The thermocouples are conducted to verify the temperature, and the coercivity experiment is used to verify the stress distribution. Results show that two heating bands width of 80 mm and a peak temperature of 120°C are the optimal S-PWHT parameters with the stress reduced by 61%. Besides, the levels of stress reduction on the inner surface and the HAZ are higher than those on the outer surface and the base metal, respectively. The high-stress zone is transferred from the inner surface to the outer surface, and from the HAZ to the base metal. Furthermore, the stress reduction mechanism of S-PWHT has been revealed through constraint theory. Temperature change is the initial force, and the constraint is the driving force for stress reduction.

Selection of a suitable technology for the repair of forged structural steel using surfacing welding method

The article discusses the selection of an appropriate technology for the repair of forged structural steel through the use of hardfacing MMA welding method. Investigated, additionally, is the wear resistance of the hardfacing layers. The method used to determine the wear resistance is "block on ring". The macrostructure, microstructure and Vickers microhardness (HV0.05) were also analyzed.

Research on hydrodynamics of the thermal agent flow for the beet pulp filtration drying

The reuse and recycling of secondary raw materials is essential to ensure sustainable development and the rational use of natural resources. One of the most important types of secondary raw materials is plant-based food waste, which is generated in large quantities at food processing plants, including sugar beet pulp, which is a valuable resource for further use. One of the main problems with using beet pulp is its high moisture content, which is ≈ 80 % wt. It is proposed to dry beet pulp by filtration drying, which is highly efficient. The calculation of industrial equipment for filtration drying should take into account the costs of overcoming the hydraulic resistance of a stationary layer of material. The aim of the article was to study the hydrodynamics of the flow of a thermal agent through a stationary layer of beet pulp of different heights and to perform computer modelling of this process. The obtained results will allow predicting the hydraulic resistance of a material layer of different heights and the required pressure drop to ensure the course of the drying process under various possible technological modes. For computer modelling of the flow of a thermal agent through a stationary layer of beet pulp, the porous media method was used in the ANSYS Fluent 2022 R2 software package. The process was simulated on the basis of the Navier-Stokes system of differential equations and the flow continuity equation with the additional use of the Darcy equation to determine the value of the hydraulic resistance of the layer ΔP. Computer simulations of the hydrodynamics of the thermal agent flow through a stationary layer of beet pulp were performed for the range of stationary layer heights H = 90÷110 mm with an interval of 5 mm. The obtained data showed a relative average deviation of 2.19 % from the experimental data, which indicates a high accuracy of calculations in this range. The study for the extended range of layer heights H = 80÷120 mm with an interval of 10 mm showed an increase in the relative average deviation to 4.09 % from the experimental data, but the results are still sufficiently accurate for practical use in the calculation of drying equipment. The obtained dependencies may be used to determine the value of the hydraulic resistance of a stationary layer of material using the filtration drying method and for practical calculations of drying equipment. Together with the results of the kinetic regularities of filtration drying, the obtained experimental data and computer modelling data on the hydrodynamics of the flow of a heat transfer agent through a material layer will allow us to calculate the optimal parameters of filtration drying for beet pulp and to assess the efficiency of filtration drying for drying beet pulp in comparison with other methods of dehydration.

A study on the mechanical behavior of umbilical cables under impact loads using experimental and numerical methods

Accidental impacts affect the structural integrity of umbilical cables during their life cycle. This study investigates the impact behavior of a steel tube umbilical cable using both experimental tests and numerical simulations. A series of impact tests are carried out to elucidate the failure modes and deformation responses of non-bonded multi-layer components. A three-dimensional finite element model is established and verified to capture time-history responses. Through the analysis of time-history responses, the impact energy dissipation mechanisms are investigated, and the impact resistance of armor layers is further evaluated. It is found that the armor layers and polymer sheaths dissipate only approximately one-third of the impact energy, demonstrating limited protection capability, while more impact energy is absorbed by internal functional components. The steel tube may have sustained severe damage, even though the armor layer and polymer sheath exhibit only minor damage. This work has provided a reference for the damage assessment and protection design of umbilical cables.

Water Permeability and Oxygen Transport Resistance of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer

Enhancing water management to mitigate the performance impact of humidity fluctuations is crucial in PEFC applications. A novel microporous layer (MPL) incorporated with both hydrophilic and hydrophobic properties, applied to the gas diffusion layer (GDL), has been developed and demonstrated to enhance robustness under varying humidity levels. This study utilized water permeability test results to analyze the composite MPL, distinguishing between hydrophobic and hydrophilic absolute permeability ratios. By elucidating these ratios, insights into their roles in liquid water distribution and oxygen transport resistance were gained, distinguishing the composite MPL from conventional hydrophobic and hydrophilic MPLs. Ultimately, the performance of the composite MPL under high and low humidity conditions highlighted its robustness across diverse humidity environments.

Water Permeability and Oxygen Transport Resistance of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer

Enhancing water management to mitigate the performance impact of humidity fluctuations is crucial in PEFC applications. A novel microporous layer (MPL) incorporated with both hydrophilic and hydrophobic properties, applied to the gas diffusion layer (GDL), has been developed and demonstrated to enhance robustness under varying humidity levels. This study utilized water permeability test results to analyze the composite MPL, distinguishing between hydrophobic and hydrophilic absolute permeability ratios. By elucidating these ratios, insights into their roles in liquid water distribution and oxygen transport resistance were gained, distinguishing the composite MPL from conventional hydrophobic and hydrophilic MPLs. Ultimately, the performance of the composite MPL under high and low humidity conditions highlighted its robustness across diverse humidity environments.

Stable RbCsFAPbI3 perovskite solar cell: numerical modelling and optimisation using SCAPS-1D

The studies concerning solar cell technology has consistently been captivating and inspiring, largely because of its environmentally friendly and sustainable characteristics. The outstanding electronic, optical, mechanical, and electrical characteristics of perovskite materials make them crucial for the development of the photovoltaic industry. In order to model the mixed cation Rb0.05Cs0.1FA0.85PbI3 perovskite solar cells, the SCAPS-1D tool was used. The main feature of RbCsFAPbI3 perovskite is its remarkable stability, and wide bandgap. Rubidium (Rb) and cesium (Cs) cations improve the optoelectronic characteristics of the material, resulting in less non-radiative recombination and improved charge transfer. In this work, the effects of different hole transport layers (CuSCN, CuSbS2,Cu2O) and back metal contacts (Ag, Fe, C-Cu, Au, Ni, Pt) on solar cell performance were investigated. The maximum efficiency of the solar cell has been achieved by studying various parameters like temperature, series resistance, shunt resistance, defect density, and absorber layer thickness. With FF = 84.12%, Jsc = 24.52 mA cm−2, Voc = 1.19 V, and the configuration of FTO/TiO2/RbCsFAPbI3/Cu2O/Au, the optimised device obtains a PCE of 24.64%. The impressive enhancements in performance parameters observed in the structure of the device make it highly suitable for applications in solar energy harvesting systems.

Modeling The Hydrogen Crossover Through Membrane With And Without Catalyst Layers

The hydrogen crossover flux is expressed as a function of the difference in the partial pressure of hydrogen and total pressure difference between the supply and permeate sides of a membrane. The hydrogen crossover rate was measured under several operating conditions by micro gas chromatography. The permeation flux was not influenced by the total pressure difference up to 50 kPa. A bare Nafion membrane and the membrane with catalyst layers were modeled as a stack of bulk and skin layers. Hydrogen permeability of both samples showed identical bulk layer expressed by a power-law equation of the moisture content and an Arrhenius equation of temperature with an activation energy of 22.8 kJ mol–1. The measurement of skin layer resistance wasn’t successful since the skin layer resistance was too low to be measured. A skin layer of Nafion with a catalyst layer wasn’t observed due to formation of fused layer.

Modeling The Hydrogen Crossover Through Membrane With And Without Catalyst Layers

The hydrogen crossover flux is expressed as a function of the difference in the partial pressure of hydrogen and total pressure difference between the supply and permeate sides of a membrane. The hydrogen crossover rate was measured under several operating conditions by micro gas chromatography. The permeation flux was not influenced by the total pressure difference up to 50 kPa. A bare Nafion membrane and the membrane with catalyst layers were modeled as a stack of bulk and skin layers. Hydrogen permeability of both samples showed identical bulk layer expressed by a power-law equation of the moisture content and an Arrhenius equation of temperature with an activation energy of 22.8 kJ mol–1. The measurement of skin layer resistance wasn’t successful since the skin layer resistance was too low to be measured. A skin layer of Nafion with a catalyst layer wasn’t observed due to formation of fused layer.

Influence of Fe Ions on Anode Performance and the Mechanism of Action during Copper Electrowinning Process.

The performance of the anode varies from the impurity ions in the copper electrowinning process. This work focused on the variation of the electrochemical behavior of the Pb-0.06%Ca-1.2%Sn anode as the Fe ions (Fe3+ and/or Fe2+) existed in the electrolyte by electrochemical characterization. Copper electrodeposition experiments were conducted under a current density of 300 A/m2, with the Fe ion concentration in the electrolyte controlled within the range of 0 to 20 g/L and the Cu ion concentration maintained at 45 g/L at a temperature of 45 °C. The variation in the corrosion resistance, catalytic activity, and structural composition of the anode film layer was analyzed in-depth according to the presence of Fe ions. The results show that the structure of PbO2 on the surface of the film was changed as Fe ions doped into the anode film, and the oxygen evolution activity of the anode was also improved. However, the corrosion resistance decreased with increasing Fe3+ concentration. Furthermore, the addition of 2 g/L Fe2+ in the electrolyte containing 2 g/L Fe3+ led to an elevation in the corrosion resistance of the anode to some extent and further increased the oxygen evolution activity.

Self-rectifying memristor boosts positive current to push neural network benchmarks

A synergistic interplay between the resistive layer and insulating layer show path forward for memristors that can scale up while maintaining high accuracy in synaptic weighting.

Coexistence of digital and analog resistive switching behaviors in nanocrystalline yttrium-iron-garnet thin films achieved by electrode engineering

Memristors with digital or analog resistive switching characteristics have the potential to acquire high-performance data storage or electronic synaptic device applications, respectively. It is considerably important to realize coexistence of digital and analog resistive switching characteristics for high-performance memristor applications. In this study, the nanocrystalline yttrium-iron-garnet Y3Fe5O12 (YIG) thin film was synthesized on Pt substrates by a facile solution-processed method, and it can be used as resistive switching layer for fabricating memory devices. The digital and analog resistive switching characteristics in YIG thin film devices were achieved by employing inert platinum and active silver electrodes, respectively. Oxygen vacancy-controlled conductive filaments (CFs) with Pt/YIG/Pt structure exhibited digital resistive switching behavior which can be modulated by changing voltage polarity. The resistive switching mode with positive Set/Reset in the Pt/YIG/Pt device acquired superior resistive switching properties. Ag/YIG/Pt device exhibited analog resistive switching characteristics based on the formation of Ag-based CFs. The conductance increase during Set operation and decrease during Reset process by adjusting current gradients and voltage windows, respectively. The present study exhibits an effective path to obtain the digital and analog resistive switching properties, which opens a door for understanding and optimizing resistive switching performance.

Investigating Arctic Permafrost Dynamics Using Electrical Resistivity Imaging and Borehole Measurement in Svalbard

This study utilized electrical resistivity imaging (ERI) to investigate subsurface characteristics near Nicolaus Copernicus University Polar Station on the western Spitsbergen-Kaffiøyra Plain island in the Svalbard archipelago. Surveys along two lines, LN (148 m) collected in 2022 and 2023, and ST (40 m) collected in 2023, were conducted to assess resistivity and its correlation with ground temperatures. The LN line revealed a 1- to 2-m-thick resistive unsaturated outwash sediment layer, potentially indicative of permafrost. Comparing the LN resistivity result between 2022 and 2023, a 600 Ohm.m decrease in the unsaturated active layer in 2023 was observed, attributed to a 5.8 °C temperature increase, suggesting a link to global warming. ERI along the ST line depicted resistivity, reaching its minimum at approximately 1.6 m, rising to over 200 Ohm.m at 4 m, and slightly decreasing to around 150 Ohm.m at 7 m. Temperature measurements from the ST line’s monitoring strongly confirmed that the active layer extends to around 1.6 m, with permafrost located at greater depths. Additionally, water content distribution in the ST line was estimated after temperature correction, revealing a groundwater depth of approximately 1.06 m, consistent with measurements from the S4 borehole on the ST line. This study provides valuable insights into Arctic subsurface dynamics, emphasizing the sensitivity of resistivity patterns to climate change and offering a comprehensive understanding of permafrost behavior in the region.

Enhanced Photoelectrochemical Water Splitting Using NiMoO4/BiVO4/Sn-Doped WO3 Double Heterojunction Photoanodes.

Efficient photoelectrochemical (PEC) water splitting systems in photoelectrodes are primarily challenged by electron-hole pair recombination. Constructing a heterostructure is an effective strategy to overcome this issue and to enhance PEC efficiency. In this study, we integrated NiMoO4, known for its proper electrocatalytic conductivity, into a BiVO4/Sn-doped WO3 heterojunction using solution-based hydrothermal and spin-coating methods, forming an innovative double heterojunction concept. The resulting NiMoO4/BiVO4/Sn:WO3 triple-layer heterojunction photoanode exhibits a photocurrent density of 2.06 mA cm-2 in a potassium borate buffer (KBi) electrolyte at 1.23 V vs RHE, outperforming the bilayer BiVO4/Sn:WO3 heterojunction (1.45 mA cm-2) and Sn:WO3 photoanodes (0.55 mA cm-2) by approximately 1.4 and 3.7 times, respectively. Remarkably, the NiMoO4/BiVO4/Sn:WO3 double heterojunction photoanode exhibits notable stability, showing only an approximate 30% reduction in initial photocurrent density after 10 h of measurement in the KBi electrolyte without a hole scavenger. This stability is attributed to the excellent corrosion resistance of the thin NiMoO4 layer, effectively protecting the bilayer BiVO4/Sn:WO3 heterojunction photoanode from photocorrosion. Our findings show how this novel double heterojunction, established through simple and cost-effective solution-based methods, offers a promising approach to enhancing PEC water splitting applications.

Complex Diagnostics of Silicon-on-Insulator Layers after Ion Implantation and Annealing

A technology was developed for activating ion-implanted dopants in silicon-on-insulator layers at a low annealing temperature (600°C) using the pre-amorphization technique of a silicon device layer. In the case of phosphorus implantation, silicon was amorphized directly by dopant ions. In the case of boron implantation for pre-amorphization, the layers were preliminary irradiated with argon or fluorine ions. Complex diagnostics of the implanted layers was carried out using secondary ion mass spectrometry, X-ray diffractometry and small-angle X-ray reflectometry. The combination of methods made it possible to characterize the impurity distribution, the degree of silicon crystallinity, the layer thicknesses, and the interface widths in structures. The results of diagnostics of the structure and composition correlate well with calculations in the SRIM software package and the electrophysical characteristics of the layers after annealing. It was shown that the use of argon for pre-amorphization of silicon interfered with the recrystallization process and did not make it possible to achieve acceptable electrical characteristics of the doped layer. Amorphization with phosphorus and pre-amorphization with fluorine during boron implantation allowed obtaining the required values of the resistance of the doped layers after annealing at a temperature of 600°C. The use of a complex approach made it possible to optimize the modes of amorphization, ion doping, and annealing of silicon-on-insulator structures at low temperatures, necessary for the creation of light-emitting device structures based on silicon-germanium nanoislands.

Impact of Glow-Discharge Nitriding Technology on the Properties of 3D-Printed Grade 2 Titanium Alloy.

This study presents a comparative analysis of the corrosion resistance of nitrided layers on conventional Grade 2 titanium alloy and those produced by direct metal laser sintering (DMLS). Low-temperature glow-discharge nitriding of the tested materials was carried out using conventional glow-discharge nitriding (so-called nitriding at the cathode potential-TiN/CP) and with the use of an "active screen" (nitriding at the plasma potential-TiN/PP). The TiN + Ti2N + Ti(N) layers were characterized by their microstructure, nanohardness profile distribution, surface topography, and corrosion resistance. The reduction in the cathodic sputtering phenomenon in the process using the active screen allowed the creation of surface layers that retained the topography of the base material. The parameters of the glow-discharge treatment led to grain growth in the printed substrates. This did not adversely affect corrosion resistance. The corrosion resistance of nitrided layers on the printed titanium alloy is only slightly lower than that of layers on the conventional Grade 2 alloy. Iron precipitates at grain boundaries facilitate increased nitrogen diffusion, resulting in reduced nitrogen concentration in the surface layer, slight changes in corrosion potential values, and increased nitrogen concentration in the Ti(N) diffusion layer.