Resistive Layer Research Articles

Thermal conductivity of snow cover

Important parameters when using snow as a building material and designing the interaction of engineering structures for various purposes with snow are the density and coefficient of thermal conductivity of the snow cover. The purpose of the article was to evaluate the accuracy of calculating the thermal conductivity coefficient of a two-layer snow cover, depending on the degree of compaction of one of the layers. Two approaches to determining the thermal conductivity coefficient are considered: as a layered structure and as an equivalent homogeneous structure having a constant average density. Classical formulas for determining the coefficient of thermal conductivity from density (Abels formula) and density from the depth of snow cover (Abe formula) were used for calculations. As a result of the analysis and complex variant calculations presented in the form of graphs, the following conclusions are made. With a linear dependence of the thermal conductivity coefficient on the density of snow, the choice of one or another method for calculating the thermal conductivity coefficient of a two-layer snow cover does not matter: an error in calculations will always be zero. With a nonlinear dependence of the thermal conductivity coefficient on the density of snow, the error increases with an increase in the compaction coefficient of one of the layers. For example, with a compaction coefficient of 1.5, the relative calculation error does not exceed 4%. And with an increase in the compaction coefficient to 3.5, the error increases to 31%. That is, it increases almost 8 times. The analysis of the results allowed us to conclude that when compacting one of the layers by less than 2 times (compaction coefficient k2), the use of the concept of “average density of snow cover” in thermal calculations to determine the thermal resistance of snow cover is quite acceptable. With an increase in the degree of compaction of one of the layers by more than two times, it is necessary to determine the thermal conductivity coefficient of each layer and calculate the total thermal snow cover as the sum of the thermal resistances of the individual layers.

Modeling Borehole Resistivity Logs with Exponentially Graded Multilayered Soil Inversion for Electrical Engineering Applications

In this paper, we present the application of a special soil resistivity model, the Exponentially Graded Multilayered Soil model, to the interpretation of Borehole Resistivity Logging surveys. The model, which was recently introduced by the authors, offers an alternative to the interpretation provided by constant resistivity layer models. The model is applied to synthetic soil surveys as well as to a real survey that is not satisfactorily interpreted using conventional models. This model aids in the design and calculation of grounding systems in electrical engineering, providing an alternative to calculations performed by traditional layered models.

Surface-Reconstructed CdNNi3 Antiperovskite Electrocatalyst: Unlocking Ampere-Level Current Density for Hydrogen Evolution.

Developing conductive electrocatalysts is crucial for decreasing the ohmic loss induced by electric resistance of the catalyst layer in the large-current-density hydrogen evolution reaction (HER), which has been overlooked previously. In this study, we screen a highly conductive antiperovskite CdNNi3 with negligible ohmic loss, as a highly active and durable HER electrocatalyst capable of unlocking ampere-scale current densities. CdNNi3 exhibits an impressive activity (an overpotential of 235 mV) at 1 A cm-2 and maintains its performance steadily at an ampere-scale current density (at 1 A cm-2 over 400 h). Besides, the CdNNi3-enabled anion-exchange membrane water electrolyzer outperforms that of the benchmark Pt/C, evidenced by a reduced cell voltage of 160 mV at 1 A cm-2, and presents a favorable stability at 1 A cm-2. Importantly, this study experimentally discovers the dynamic surface reconstruction phenomena of antiperovskite nitrides during alkaline HER. Theoretical analysis suggests that the presence of Cd in the reconstructed surface effectively adjusts the local electronic configuration of active sites, which promotes the adsorption of OH and reduces the binding strength to H, thereby facilitating the water dissociation step and reducing the energy barrier of the potential-determining step in the HER process.

SCAPS numerical modeling of CBTS/WO3 thin film solar cell

The quaternary compound Cu2BaSnS4 (CBTS) has emerged as a suitable and attractive light-harvesting material due to its promising optoelectronic features as well as nontoxic and low-cost constituent elements. Yet efficiency of CBTS-based solar cells did not reach the Shockley-Queisser limit. Here, what we believe to be a novel structure ITO/WO3/CBTS heterojunction solar cell is designed and modeled using a solar cell capacitance simulator in one-dimension (SCAPS-1D). In this work, a what we also believe to be a novel WO3 as a buffer layer is proposed for the first time for the efficiency enhancement of CBTS thin film solar cells. Numerical investigation of the performance of CBTS-based solar cells without and with cuprous oxide (Cu2O) back surface field (BSF) is explored. The impact of thickness, doping density, bulk, and interface defect density of an absorber, buffer and window layer, working temperature, shunt and series resistance, back contact work function, and back surface recombination velocity were analyzed and optimized without and with the BSF layer. In this work, the optimized solar cell achieved an efficiency of 18.8%, fill factor (FF) of 83.79%, short-circuit current density (JSC) of 15.99 mA/cm2, and open circuit voltage (VOC) of 1.4 V without Cu2O BSF layer at optimal CBTS absorber and WO3 buffer layer thickness of 2 µm and 0.04 µm respectively. Furthermore, the efficiency boosted to 21.12% with VOC of 1.43 V, JSC of 16.8 mA/cm2 and FF of 87.77% by inserting 0.1 µm Cu2O BSF layer. Therefore, these results will facilitate the fabrication of an efficient and low-cost CBTS-based solar cell with promising WO3 and Cu2O as buffer and BSF layer, respectively.

Analytical Model for Heat Transfer Around Energy Piles in Layered Soil With Interfacial Thermal Resistance by Integral Transform Method

ABSTRACTEnergy piles are commonly deployed in vertically layered geological conditions due to the geological structure and pile foundation backfill. The imperfect contact between adjacent soil layers results in resistance to heat transfer at the interface, known as the interfacial thermal resistance effect. In this paper, the energy pile was simplified as a finite‐length solid cylindrical heat source, and an analytical model was established for layered heat transfer of energy piles considering the interfacial thermal resistance effect. The Laplace‐domain solutions to the temperatures in the layered ground were derived by using the finite Hankel and Laplace transforms. The Crump method was subsequently employed to numerically invert Laplace‐domain solutions to the time‐domain solutions. The proposed model was validated by comparing with an analytical solution of a homogeneous model and COMSOL numerical solution. These solutions were used to analyze the temperature response around energy piles considering interfacial thermal resistance. Finally, a parametric study was performed to explore the effects of interfacial thermal resistance and other thermal properties of the soil layer on the layered heat transfer of energy piles.

Honeycomb‐Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer

AbstractAchieving robust long‐term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low‐temperature synthesis of iridium oxide foam platelets comprising edge‐sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic‐to‐microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam‐like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single‐cell PEMWE based on honeycomb‐structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere‐level current densities and to remain stable for more than 2000 hours.

Honeycomb-Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer.

Achieving robust long-term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low-temperature synthesis of iridium oxide foam platelets comprising edge-sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic-to-microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam-like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single-cell PEMWE based on honeycomb-structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere-level current densities and to remain stable for more than 2000 hours.

Application of Combined Geoelectrical Techniques for Groundwater Exploration at Federal University Gusau, Zamfara and its Environ, Northwest Nigeria

Study’s Excerpt Integrated approach combining Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) is used to delineate groundwater potential in the study area. The results revealed that the water bearing aquifers in the study area are fractured basement layers at varying depths between 15 and 105 meters. This research provided a robust framework for groundwater exploration in arid and geologically complex terrains. Full Abstract The area of study is currently facing an acute water shortage due to the dominant lithological framework that underlies the region and its fragile climate condition. As such, this study aimed at unearthing the groundwater potential of the area using a combined three geoelectrical techniques. Techniques such as Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) were employed in the delineation of the groundwater potential of the area. Using an ABEM SAS-4000 Resistivity meter and a PQWT-TC150 water-detector equipment, respectively. Wennar array was employed for the conduct of ERT while Schlumberger configuration was used for VES data collection. The measured apparent resistivity value was inputted into RES2DIV software and subjected to an inversion process to generate the resistivity structural image of the subsurface. However, IP2WIN software was used for the VES data interpretation. The result of the ERT method revealed two to three geoelectrical resistivity layers: an overburdened layer of topsoil/laterite with resistivity values ranging from 6.86 Ωm to 1095 Ωm and thicknesses of 1-13 meters, a weathered/fractured basement layer, interpreted as the aquifer unit, with resistivity values between 28.7 Ωm and 345 Ωm, and thicknesses ranging from 6 - 30 meters; and a fresh/slightly fractured basement layer with resistivity values from 367 Ωm to 6899 Ωm. NEF method revealed the thickness and depth of the aquiferous layer across the six profile lines to range between 15-60m, 30-90m, 15-85m, 20-80m, 45-105m, and 20-40m respectively, with points on profile five (5) identified as the most promising site with regards to groundwater development. VES result identifies weathered and fractured layers as the major aquiferous units with resistivity values ranging from 9.965 Ωm to 9651 Ωm and 21.7 Ωm to 859 Ωm respectively with fracture thickness reaching up to 60m in some instances. The result goes in line with the outcome of both NRF and ERT techniques. The geological interference of this lithology on groundwater exploration reveals both the weathered overburden and fractured basement as aquiferous units in the study area. The study identified several promising aquiferous zones at depths ranging from 15 to 105 meters, with fractured basement layers serving as primary reservoirs for groundwater development.

Research on the multi environmental corrosion characteristics and mechanism of B4C doped Fe–Cr–Ni composite coating produced by laser cladding

Different Fe–Cr–Ni composite coatings doped with B4C were produced on the surface of Cr12MoV steel by laser cladding. Special attention was paid to the effects of B4C content on the phase composition, microstructure, and corrosion resistance of the cladded layers. The results indicated that the Fe–Cr–Ni composite coating was primarily composed of α-(Fe, Cr) and γ-(Ni–Cr–Fe) solid-solution phases, as well as Fe2B, M7C3, Fe3Si and M23C6 phases. Once the B4C content increased to 10 wt%, the microstructure of the cladding layer became coarse and exhibited the prominent carbide agglomeration. The composite coatings with different B4C contents exhibited superior corrosion resistance compared to the pure substrate in both 3.5 wt% NaCl and 1 mol/L HCl solutions. Furthermore, as the B4C content increased, the corrosion resistance of the coating initially increased and then declined. In particular, the Fe–Cr–Ni composite coating with an 8 wt% B4C content experienced the pronounced passivation in the corrosive media and possessed the optimal corrosion resistance due to the synergistic effect of the passive film and carbide barrier layer.

Microstructure and friction properties of NiTi2-based composite layer prepared by ultrasonic assisted underwater wet laser deposition

An in situ TiC-enhanced NiTi2-based composite deposition layer was prepared by ultrasonic assisted underwater wet laser deposition. The evolution of the microstructure and interface state, and the friction properties in the air and brine solution environments of the deposition layer were analyzed and researched. The results demonstrated that the thermal and steady-state cavitation from ultrasound effects increase the total energy of the melt pool and promote mixing. The dilution rate of the ultrasonic assisted underwater laser deposition layer increases to 86.72 % compared with that of the underwater laser deposition layer (78.75 %). Ultrasonic reduced underwater laser deposition defects such as lack of fusion and weld slag, and enhanced the wettability between the deposition layer and substrate. The contact angle of the UWNT layer (24.40°, in average) is smaller than the WNT layer (29.80°, in average). Ultrasonic shortened the contact time between the deposition layer surface and the solution, which reduced the reaction of the Ni element with the brine solution. It also transformed the deposition layer from hypereutectoid microstructure to hypoeutectic microstructure and from planar interface to cellular interface. With the effect of the ultrasonic field, the elements in the deposition layer become more uniformly distributed and the secondary phases undergo spheroidization. In the ultrasonic assisted deposition layer, stress-induced FCC-Ti was discovered. Ultrasonic field also reduced the dispersion of the microhardness and increased the average microhardness to 863.3 ± 45.1 HV0.3. Tribology properties show that ultrasonic field effectively improved the wear resistance and friction stability of the ultrasonic assisted deposition layer. The COF of the ultrasonic assisted deposition layer was less affected by the environment, with values of 0.25 and 0.24 observed in air and brine solution, respectively. Overall, the research results in this paper can provide a new insight to improve the surface properties of NiTi2-based alloy underwater laser deposition.

Surface modification of WE43 Mg alloy via combination of cold spray and micro-arc oxidation for wear related applications at high temperatures

This study investigates the high temperature wear behaviour of a WE43 Mg alloy after covering it with single and dual layer coatings. For this purpose, cold spray and micro-arc oxidation processes were employed individually and sequentially. Single-layer coatings fabricated by cold spray and micro-arc oxidation processes were Al/Al2O3 composite and MgO-based ceramic, respectively. Sequential application of cold spray and micro arc oxidation processes induced dual layer coating upon synthesizing an external Al2O3–based layer over the Al/Al2O3 composite layer. Results of the wear tests conducted under the load of 2 N revealed the superior resistance of the dual layer coated sample against the rubbing action of the counterface compared to single layer coatings. Thus, the presence of a relatively hard and tough external Al2O3-based layer over the Al/Al2O3 composite layer sustained protection up to the temperature of 320 °C, where the dominant wear mechanism was fatigue wear. However, the increase in the test temperature to 350 °C caused detachment of the external Al2O3-based layer. Reduction of the wear test load from 2 to 1 N resulted in the remaining of external Al2O3-based layer intact with the underlying Al/Al2O3 composite layer even at a test temperature of 350 °C. It is therefore concluded that the combination of cold spray and micro-arc oxidation processes is promising to broaden the reliable use of WE43 and other Mg alloys in wear related applications at high service temperatures.

Demonstration of bipolar resistive memory fabricated using an ultra-thin BaTiOx resistive switching layer with a thickness of ∼5 nm

In this study, a high-performance non-volatile bipolar resistive random-access memory (RRAM), which was fabricated using an ultra-thin barium titanate (BaTiOx, BTO) film as a resistive switching (RS) layer, was demonstrated. The BTO RS layers, whose thicknesses were only about 5 nm, were prepared using radio-frequency sputtering under different oxygen flow rates. Introduction of oxygen was used to modify the chemical compositions of the BTO films. Copper was used as the top electrode material to realize a Cu/BTO/n+-Si electrochemical metallization memory, where the resistance switching was triggered by electrochemical reaction of Cu electrode. The RRAM could repeatedly and consistently switch between a high-resistance state and a low-resistance state over 300 cycles. A large memory window of 105 and a long data retention time of >1.5 × 104 s both at room temperature and 85 °C were observed. Moreover, the Cu/BTO/n+-Si RRAM showed high switching speeds of 60–70 ns.

Geoelectrical resistivity mapping for sustainable groundwater management in Umuahia South: Insights from vertical electrical sounding

The study of geoelectrical resistivity provides critical insights into subsurface characteristics and aquifer dynamics, particularly in regions with varying geological formations. This research investigates the geoelectrical properties of the aquifer system in Umuahia South, highlighting its significance for sustainable groundwater management. The primary aim of this study is to characterize the geoelectrical layers, assess aquifer thickness and resistivity, and evaluate the implications for groundwater resource management. Vertical Electrical Sounding (VES) was conducted across ten locations to measure the resistivity and thickness of subsurface layers. The data collected were analyzed to identify distinct geoelectrical layers, their respective resistivity values, and thicknesses. The study reveals significant variations in aquifer properties across the region, with VES 1 showcasing the largest thickness of 69.2 m and VES 9 the smallest at 5.2 m. Aquifer thickness decreases from the Benin Formation toward the Ameki and Ogwashi-Asaba Formations. Hydraulic conductivity ranges from 0.207 to 0.954 m/day, indicating varying groundwater flow potential, while transmissivity values vary from 4.965 to 30.441 m²/day, with 60% of aquifers classified as intermediate. Groundwater Potential Index (GWPI) highlights approximately 70% of the area as high potential, underscoring the need for targeted management strategies to optimize water resource extraction and sustainability. The variability in resistivity and thickness across the study area suggests significant subsurface heterogeneity. High resistivity values indicate favorable conditions for groundwater flow, particularly in areas like VES 6. Conversely, lower resistivity in locations such as VES 9 indicates potential challenges for groundwater storage. This study provides vital information on the aquifer system in Umuahia South, emphasizing the need for targeted groundwater management strategies based on the geoelectrical characteristics identified. The research contributes to a deeper understanding of the aquifer dynamics in the region and offers a framework for sustainable groundwater resource management, highlighting the importance of geoelectrical assessments.

Characterizing groundwater contamination flow-paths and heavy metal mobilization near a waste site in Southwestern Nigeria

This study investigates potential groundwater contamination near a waste disposal site in southwestern Nigeria. The area's complex geological setting, characterized by fractured rock formations, posed significant challenges for traditional monitoring methods. To address these challenges and comprehensively assess groundwater conditions, we employed a combined approach utilizing Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), and geochemical analysis of heavy metals and water conductivity. This approach enabled the investigation of groundwater levels, identification of potential contamination zones, and delineation of contaminant flow paths. GPR identified a shallow zone, termed the “shadow zone,” with conductive residues indicating contaminants with anomalous conductivity ranging from 1 to 1.5 m. An intermittent reflection zone at a depth of 1.5–3.5 m suggested the potential presence of leachate-impacted groundwater. ERT confirmed a shallow resistive layer at depths of 0–2 m, attributed to compacted waste and topsoil, around the abandoned main dumpsite. Below this layer, a zone of low resistivity, decreasing downward through a porous weathered zone, was observed. This corresponded to high water conductivity in well data, ranging from 21 to 147 mS/m (equivalent to 6.80 to 47.62 Ω-m), indicating a high conductive anomaly suspected to be a leachate plume at depths of 2–10 m in a sandy-gravelly weathered zone. Validation against ground truth data confirmed the correlation between radar signatures, geoelectrical imaging, and subsurface lithology. Analysis of well and soil samples revealed concerningly elevated concentrations of cadmium, mercury, lead, arsenic, and cobalt, ranging from 641 to 1175 ppb, exceeding established safety limits for drinking water. Additionally, soil samples showed elevated levels of nickel and chromium, generally ranging from <0 to <1 ppb. These findings highlight the significant risk of groundwater contamination due to the proximity of the leachate zone to the groundwater table in the weathered basement complex. This study demonstrates the effective integration of geophysical and geochemical methods for comprehensive mapping of contaminated zones and identification of preferential pathways for contaminant migration. The findings underscore the critical need for implementing comprehensive risk assessment methodologies in similar complex geological settings.

A low-cost device for measuring TEER at cultivation of epithelial/endothelial cells on inserts.

Background: The barrier properties of epithelial and endothelial cells are usually studied in vitro when cells are cultured on mesh inserts in culture plates, and it is necessary to assess the state of the cell monolayer on the membrane of the inserts before the experiment. Typically, monolayer density is analyzed by passing a fluorescent label through the insert with cells or by measuring the transendothelial resistance (TEER) of the cell layer. Many studies use both methods of assessing monolayer integrity in parallel, depending on the purpose of the study. The TEER method also allows to record early changes in the monolayer state under the action of various substances. Aim of this work is to demonstrate the possibility of TEER measurements using the proposed device (conductometer) made from freely available components using endothelial/epithelial cells as an example. Materials and Methods. A device (conductometer) for measuring TEER, created on the basis of easily accessible components, is presented. The device was tested by culturing two cell lines – hybridoma of endothelial origin Ea.hy926 and human colon adenocarcinoma Caco-2. Caco-2 cells were cultured for 22 days and Ea.hy926 cells were cultured for 7 days. The integrity of the cell monolayer and the density of intercellular contacts were evaluated by the TEER value determined by the proposed conductometer, as well as by the fluorescein permeability of the cell monolayer. Results: The results of TEER measurements using the proposed device and at the same time, the fluorescein permeability of the cell monolayer during the cultivation of Caco-2 and EA.hy926 cells are presented. For Caco-2 cells from the moment of 100% confluence the TEER value gradually increased reaching maximum values by 20-21 days, after which it decreased slightly. The permeability values decreased as the cells were cultured, indicating the formation of dense contacts. For EA.hy926 cells the rise in TEER values are observed on day 3 and decrease was observed on day 7. The results of TEER and permeability obtained by the proposed conductometer have a strong inverse correlation for both cell lines and are in good agreement with each other. Conclusions. The presented device, made on the basis of simple and affordable components, is similar to commercially available devices and can be used to study the integrity and density of a monolayer in the cultivation of epithelial/endothelial cells, to study the processes of trans/paracellular transport under the action of various substances, as well as in experiments with the co-cultivation of various cell lines.

Fabrication and Characterization of Biocompatible Multilayered Elastomer Hybrid with Enhanced Water Permeation Resistance for Packaging of Implantable Biomedical Devices

This study presents the synthesis and characterization of hexadecyl-modified SiO2 (HD-SiO2) nanoparticles and their application in the fabrication of a multilayered elastomer hybrid sheet to enhance water resistance in implantable biomedical devices. The surface modification of SiO2 nanoparticles was confirmed via FT-IR and TGA analyses, showing the successful grafting of hydrophobic hexadecyl groups. FE-SEM and DLS analyses revealed spherical HD-SiO2 nanoparticles with an average size of 360 nm. A multilayered elastomer hybrid sheet, consisting of a PDMS-based circuit-protecting body, a water resistance layer of HD-SiO2, a planarization layer, and a biocompatible layer of polydopamine, was fabricated and characterized. The water resistance layer exhibited superhydrophobic properties, with a water contact angle of 154.7° and a 27% reduction in water vapor transmission rate (WVTR) compared to the circuit-protecting body alone. The device packaged with both the circuit-protecting body and water resistance layer demonstrated a tenfold increase in operational lifespan in water medium compared to the device without the water resistance layer. Cytotoxicity and cell proliferation tests on human dermal fibroblast cells (HDFn) confirmed the biocompatibility of the multilayered sheet, with no significant cytotoxicity observed over 48 h.

Carrier Scattering Analysis in AlN/GaN HEMT Heterostructures with an Ultrathin AlN Barrier

Experimental AlN/GaN heterostructures (HSs) with an ultrathin AlN barrier were obtained using molecular beam epitaxy with plasma activation of nitrogen. The layer resistance of the optimized structures was less than 230 Ω/¨. The scattering processes that limit the mobility of two-dimensional electron gas in undoped AlN/GaN HSs with an ultrathin AlN barrier have been studied. It is shown that in the ns range characteristic of AlN/GaN HEMT HSs (ns 1 × 1013 cm–2), a noticeable contribution to the scattering of charge carriers is made by the roughness of the heterointerface.

An improved 4H-SiC trench MOS barrier Schottky diode with current spreading layer and low resistance layer

This paper investigates an improved trench MOS barrier Schottky (TMBS) structure with extra double epitaxial layers (DE-TMBS) based on the conventional TMBS (C-TMBS) featuring a high-doped N-type current spreading layer (CSL) and a high-doped low resistance layer (LRL). Compared to the C-TMBS, the CSL in the improved structure is grown on the N-type drift region, and the LRL is extended on the CSL. According to the numerical simulations and analytical models, the specific on-resistance (Ron,sp) of DE-TMBS can be significantly reduced compared to the conventional one. This is primarily due to the high doping concentration in CSL, which effectively lowers both the JFET resistance and spreading resistance. Additionally, the increased doping concentration in LRL reduces the channel resistance and JFET resistance. Moreover, the doping concentration and thickness of CSL and LRL are optimized to maximize the figure of merit (FOM), that Ron,sp is reduced by 40.9 % and the FOM (BV2/Ron,sp) is improved by 67.9 % compared to the C-TMBS structure.

Microstructure and properties of TiC ceramic powder on a cobalt-based alloy obtained via electromagnetic-assisted laser metal deposition

The crack sensitivity of laser metal ceramic deposition is an important factor restricting its development. In this paper, a TiC-reinforced cobalt-based alloy was deposited on 300M steel using electromagnetic-assisted laser metal deposition technology. The electromagnetic composite effect on the microstructure, mechanical properties, magnetic properties, wear resistance and crack sensitivity of the laser metal deposition layer was discussed. Under the action of an electromagnetic field, the size of the TiC decreased by 54.6% compared with that of the deposited layer without an electromagnetic field. The effect of the electromagnetic composite field can reach the bottom of the molten pool, thus refining the grain size at the bottom of the coating. This resulted in a 22% increase in the hardness of the deposition layer. The electromagnetic field effect reduces the elastic modulus of the deposition layer, thus improving the mechanical properties of the coatings. In addition, compared with that of the deposition layer without an external field, the wear of the deposition layer with an electromagnetic force is obviously reduced. With increasing electromagnetic parameters, the wear resistance of the deposit increased gradually, and the thermal expansion coefficient decreased significantly, which played an important role in improving the crack resistance and comprehensive properties of the deposition layer under extreme working conditions.

Eutectic resolidification and ultrafast self-quenching of the microstructure in the surface layer of high-speed steel by scanning electron beam treatment

Improving the service life and efficiency of high-speed steel (HSS) tools remains a formidable challenge. Herein, scanning electron beam (SEB) was employed to modify the surface of M2 HSS. Results revealed that SEB induced eutectic resolidification and ultrafast self-quenching of microstructure in surface layer of HSS. The melted layer exhibited a microstructure comprising martensite, residual austenite, dispersed finely rod-like MC and lamellar M2C eutectic carbides along grain boundaries. Martensite and eutectic carbide grid structure significantly enhanced the hardness and wear resistance of surface layer. Compared to substrate, the microhardness of SEB sample was elevated by more than threefold, reaching 914.7HV0.2, which exceeded the hardness (828.6HV0.2) of conventional quenching treatment. Notably, the wear volume of SEB sample had been reduced to 0.54 × 10−11 m3, resulting in a wear resistance that was 3.8 times greater than that of quenched sample.