Search Results (564)

This study investigates the thermal stability and microstructural evolution of the solid electrolyte medium used in DLyte^® dry electropolishing and dry anodizing processes. Samples were thermally aged between 30 °C and 45 °C to simulate Joule heating during industrial operation. Visual and SEM analyses revealed shape deformation and microcrack formation at temperatures above 40 °C, potentially reducing particle packing efficiency and electrolyte performance. Particle size distribution shifted from bimodal to trimodal upon aging, with an overall size reduction of up to 39.5% due to dehydration effects, impacting ionic transport properties. Weight-loss measurements indicated a diffusion-limited dehydration mechanism, stabilizing at 15–16% mass loss. Fourier transform infrared analysis confirmed water removal while maintaining the essential sulfonic acid groups responsible for ionic conductivity. In dry anodizing tests on titanium, aged electrolytes enhanced process efficiency, producing TiO₂ films with improved optical properties—color and brightness—while preserving thickness and uniformity (~70 nm). The results highlight the need to carefully control thermal exposure to maintain electrolyte integrity and ensure consistent process performance. Full article

This study systematically investigates 50 μm-diameter 631 stainless steel fine wires subjected to both sequential and simultaneous electrothermomechanical loading to simulate probe spring conditions in microelectronic test environments. Under cyclic current loading (~10⁴ A/cm²), the 50 μm 631SS wire maintained electrical integrity up to 0.30 A for 15,000 cycles. Above 0.35 A, rapid oxide growth and abnormal grain coarsening resulted in surface embrittlement and mechanical degradation. Current-assisted tensile testing revealed a transition from recovery-dominated behavior at ≤0.20 A to significant thermal softening and ductility loss at ≥0.25 A, corresponding to a threshold temperature of approximately 200 °C. These results establish the endurance limit of 631 stainless steel wire under coupled thermal–mechanical–electrical stress and clarify the roles of Joule heating, oxidation, and microstructural evolution in electrical fatigue resistance. A degradation map is proposed to inform design margins and operational constraints for fatigue-tolerant, electrically stable interconnects in high-reliability probe spring applications. Full article

This paper presents a novel approach employing localized annealing through Joule heating to enhance the performance of Thin-Film Piezoelectric-on-Silicon (TPoS) MEMS resonators that are crucial for applications in sensing, energy harvesting, frequency filtering, and timing control. Despite recent advancements, piezoelectric MEMS resonators still suffer from anchor-related energy losses and limited quality factors (Qs), posing significant challenges for high-performance applications. This study investigates interface modification to boost the quality factor (Q) and reduce the motional resistance, thus improving the electromechanical coupling coefficient and reducing insertion loss. To balance the trade-off between device miniaturization and performance, this work uniquely applies DC current-induced localized annealing to TPoS MEMS resonators, facilitating metal diffusion at the interface. This process results in the formation of platinum silicide, modifying the resonator’s stiffness and density, consequently enhancing the acoustic velocity and mitigating the side-supporting anchor-related energy dissipations. Experimental results demonstrate a Q-factor enhancement of over 300% (from 916 to 3632) and a reduction in insertion loss by more than 14 dB, underscoring the efficacy of this method for reducing anchor-related dissipations due to the highest annealing temperature at the anchors. The findings not only confirm the feasibility of Joule heating for interface modifications in MEMS resonators but also set a foundation for advancements of this post-fabrication thermal treatment technology. Full article

A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl₄) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural and chemical properties of the synthesized TiNCl were characterized through multiple analytical techniques. X-ray diffraction (XRD) patterns confirmed the presence of TiNCl phase, while Raman spectroscopy data showed no detectable oxide impurities. Fourier transform infrared spectroscopy (FTIR) analysis revealed characteristic Ti–N stretching vibrations, further confirming successful titanium nitride synthesis. Transmission electron microscopy (TEM) imaging revealed thin, plate-like nanostructures with high electron transparency. These analyses confirmed the formation of highly crystalline TiNCl flakes with nanoscale dimensions and minimal structural defects. The material exhibits excellent structural integrity and phase purity, demonstrating potential for applications in photocatalysis, electronics, and energy storage. This work establishes FJH as a sustainable and scalable approach for producing MXenes with controlled properties, facilitating their integration into emerging technologies. Unlike conventional methods, FJH enables rapid, energy-efficient synthesis while maintaining material quality, providing a viable route for industrial-scale production of two-dimensional materials. Full article

In this work, a finite element modelling methodology is presented for the prediction of the bending behaviour of a glass fibre-reinforced elastomer composite with embedded shape memory alloy (SMA) wire actuators. Three configurations of a multi-layered composite with differences in structural stiffness and thickness are experimentally and numerically analysed. The bending experiments are realised by Joule heating of the SMA, resulting in deflection angles of up to 58 deg. It is shown that a local degradation in the structural stiffness in the form of a hinge significantly increases the amount of deflection. Modelling is fully elaborated in the finite element software ANSYS, based on material characterisation experiments of the composite and SMA materials. The thermomechanical material behaviour of the SMA is modelled via the Souza–Auricchio model, based on differential scanning calorimetry (DSC) and isothermal tensile experiments. The methodology allows for the consideration of an initial pre-stretch for straight-line positioned SMA wires and an evaluation of their phase transformation state during activation. The results show a good agreement of the bending angle for all configurations at the activation temperature of 120 °C reached in the experiments. The presented methodology enables an efficient design and evaluation process for soft robot structures with embedded SMA actuator wires. Full article

This paper presents a numerical study of the thermal behavior of grounding electrodes subjected to fault currents, focusing on Joule heating within both the electrode and the surrounding soil. A one-dimensional transient model is developed, accounting for heat generation due to both internal resistance in the electrode and current leakage into the soil. The model incorporates the temperature dependence of electrical resistivity, particularly emphasizing the nonlinear and material-specific behavior observed in soils, as captured by three different resistivity models. The temperature–resistivity coupling induces a feedback mechanism that dynamically alters the current distribution and the resulting temperature profiles. A numerical procedure was implemented to simulate this process, following a computational flowchart that captures the interaction between thermal and electrical fields over time. The model was applied to synthetic test cases involving different soil types, segmentation strategies, and resistivity behaviors. The results reveal significant differences between resistivity models, affecting both the magnitude and distribution of grounding potential and temperature fields. In particular, elevated temperatures were observed in regions where current density concentrates—such as corners and exposed ends of the electrode—highlighting the need for targeted reinforcement to prevent thermal degradation. The proposed model provides a practical tool for evaluating the thermal performance of grounding systems under extreme conditions, offering insight into design optimization and material selection. Full article

This study aims to explore a new concept for a Power to Heat (P2H) device and demonstrate its effectiveness compared to a thermal heating method. The proposed concept is a medium-temperature system where electro-thermal conversion occurs via the Joule effect in a metallic tube (resistive element). This tube also serves as a heat exchange surface between the heat transfer fluid and the thermal storage medium. The heat storage material here proposed consists of base concrete formulated on purpose to ensure its operation at high temperatures, good performance and prolongated thermal stability. The addition of 10%_wt phase change material (i.e., solar salts) stabilized in shape through a diatomite porous matrix allows the energy density stored in the medium itself to increase (hybrid sensible/latent system). Testing of the heat storage module has been conducted within a temperature range of 220–280 °C. An experimental comparison of charging times has demonstrated that electric heating exhibits faster dynamics compared to thermal heating. In both electrical and thermal heating methods, the concrete module has achieved 86% of its theoretical storage capacity, limited by thermal losses. In conclusion, this study successfully demonstrates the viability and efficiency of the proposed hybrid sensible/latent P2H system, highlighting the faster charging dynamics of direct electrical heating compared to conventional thermal methods, while achieving a comparable storage capacity despite thermal losses. Full article

Hybrid fiber-reinforced polymer-laminated composites are often used under icy conditions (such as for reinforcing parts in aircraft frames and bridge beams), where there is an urgent demand for deicing. In this paper, besides the different mechanical properties of laminates along the longitudinal carbon fiber (CF) and glass fiber (GF) directions, the anisotropic electrothermal behavior of a hybrid glass/carbon fiber-reinforced epoxy (GCF/EP) is also investigated, as well as its deicing performance and self-repairing capability. The surface equilibrium temperature of GCF/EP composites can conveniently be adjusted by tuning the current magnitude and its flow direction. Compared to the longitudinal CF direction of the GCF/EP, where 0.3 A was loaded to achieve a surface equilibrium temperature of 122.8 °C, a much weaker current (0.03 A) was needed to load along the longitudinal GF direction to reach almost the same temperature. However, besides the higher flexural strength and fast temperature response, along the longitudinal CF direction, the GCF/EP exhibited excellent deicing performance, including a shorter time and larger energy efficiency. Furthermore, the self-repairing ability of the GCF/EP and its effect on the deicing performance of the composite were characterized. Studying the Joule heating effect of GCF/EP composite laminates and their corresponding deicing performance lays the foundation for their design and practical application in icy environments. Full article

This study fabricated a C/C-CuNi composite using the hydrothermal co-deposition method and investigated its friction and wear behavior as well as the underlying mechanisms after being subjected to arc discharge ablation. The results indicate that the graphitization degree of the material matrix was significantly enhanced after arc discharge ablation, accompanied by a transformation in the carbon microstructure. Carbon nanotubes and graphene structures were generated in the arc ablation zone. Under low arc discharge density, limited pits and open pores are formed on the material surface, with the generated graphene structures effectively reducing friction. Specifically, CN-5 exhibited a stable friction coefficient, a wear rate of 5.2 mg/km, and partial self-repair capability. In contrast, CN-10, under high arc discharge density, suffered from structural collapse, matrix-fiber debonding, and extensive open pores, leading to increased surface roughness. The combined effects of frictional heat and Joule heating elevated the wear surface temperature, triggering matrix oxidation and a sharp rise in wear rate to 14.7 mg/km. The wear mechanisms of C/C-CuNi composites under continuous arc conditions involve arc erosion wear, oxidative wear, abrasive wear, and adhesive wear. Full article

Winter concrete construction in cold regions faces significant challenges due to extreme subzero temperatures, and the harsh environment presents new requirement for cement-based materials to resist this hostile external condition. To address this gap, this study proposes gradient Joule heating (GJH) curing for steel-fiber-reinforced high-performance concrete (SFR-HPC) in subzero environments (−20 °C to −60 °C). Compared to room-temperature (RT) curing, GJH enabled specimens at −20 °C to −50 °C to achieve equivalent mechanical properties within a short curing duration; the compressive strength of the specimens cured at such low environmental temperature still reached up to that of the specimen cured by RT curing. Moreover, the compressive strength of the specimens cured at −60 °C retained >60 MPa despite reduced performance. Specifically, the specimens cured at −20 °C, −30 °C, −40 °C, and −50 °C for 2 days exhibited compressive strengths of 75.8 MPa, 79.2 MPa, 77.6 MPa, and 75.4 MPa, respectively. FTIR/XRD confirmed that the specimens cured by GJH showed hydration product integrity akin to RT-cured specimens. Moreover, it should be noted that early pore structure deteriorated with decreasing temperatures, but prolonged curing mitigated these differences. These results validate GJH as a viable method for in situ HPC production in extreme cold, addressing critical limitations of conventional winter construction techniques. Full article

The introduction of the Joule heating (JH) method for synthesizing turbostratic graphene has attracted considerable attention from researchers due to its promising potential for commercialization compared to earlier techniques. Numerous studies have outlined the technology’s basic operation and how parameters such as electric field, operating time, and temperature influence the quality and type of graphene produced. Despite this, there is still a lack of concise and comprehensive studies that exclusively focus on the JH method with turbostratic graphene as the target product. This review article is a facile attempt to provide the scientific community with an overview of the historical development and operational principles of Joule heating. It also discusses the structural and fundamental differences between turbostratic and conventional graphene, along with methodologies for characterizing turbostratic graphene. Furthermore, the synthesis mechanisms of turbostratic graphene via JH are analyzed, and the future perspectives for advancing this method are also presented. Full article

The world urgently needs new methods to quickly and efficiently detect mutated viruses. An RNA-AuNP-based colorimetric biosensor is a highly sensitive, specific, and cost-effective tool that enables rapid, visual detection of target molecules for applications in disease diagnostics, environmental monitoring, and forensic analysis. An RNA-AuNP-based colorimetric biosensor requires precise control over nanoparticle dispersion and aggregation, which can be achieved using temperature regulation. A novel on-chip microelectrode is proposed to induce and monitor the aggregation of RNA-attached gold nanoparticles (AuNPs) through Joule heating and impedance spectroscopy. The proposed platform is implemented based on printed circuit board (PCB) technology, which has many advantages, such as fast and easy design and fabrication, low power consumption, and low costs. Joule heating is the process in which the energy of an electric current is converted into heat as it flows through a resistance. Impedance spectroscopy is an analytical technique that measures a system’s electrical response to an applied AC signal across a range of frequencies, providing insights into a sample’s dielectric properties. The results validate that the fabricated microelectrode is capable of heating a 20 µL droplet to 75 °C within 30 s, utilizing a low power input of only 3.75 watts and successfully inducing a color change based on the presence of hepatitis C virus (HCV) RNA, while impedance readings are used to monitor the aggregation. Full article

Over the last two decades, the use of photovoltaic panels for the production of electricity has increased significantly, which leads to the need to solve the problems concerning the decommissioning and disposal of the panels and the development of appropriate technologies for their recycling. One of the key steps in this process is the separation of the tempered glass layer. Various technologies and devices are known for separating the glass of the solar panel by cutting it with a knife, as well as other instruments, with the different methods being based on mechanical, chemical, and thermal processes and accordingly having their own advantages and disadvantages. This article proposes an innovative approach for the mechanical delamination of solar panels using a metal wire heated by Joule heating, with the potential to become an energy-efficient, economical, and environmentally friendly method. This publication presents results from experiments using this type of tool to separate the layers of solar panels. Photos from a thermal camera are presented, showing the heat distribution in the panel and the reached operating temperature of the heated metal wire, necessary to soften the EVA bonding layer. Full article

The use of CFRP composite increased significantly since the last 40 years for aircraft structure. Unfortunately, such structures are subjected to significant damages if struck by lightning compared to metallic structure. This is mainly due to the low conductivity of this material, which cannot evacuate the current without high Joule heating. Lightning strike-induced damage in a composite laminate is composed of in-depth delamination, fibre breakage, and resin deterioration due to the surface explosion and the core current flow linked to interaction of the arc with the surface. But very rare previous studies dedicated to the analysis of damage as a direct effect of lightning have considered the spurious effect of the paint that always covers real aeronautic structures neither on the thermal nor the mechanical loads that are the root cause of these damages. We present in this paper a coupled non-destructive and destructive damage analysis to support the proposition of damage scenarios depending on the presence and thickness of the paint. The mechanical and thermal sources contribution in the global loading on the core damage is discussed, which confirms previous studies’ analysis and modelling and is in accordance with existing works in the literature. Full article

Organic phase-change materials (PCMs) offer great promise in addressing challenges in thermal energy storage and heat management, but their applications are greatly limited by low energy density and a rigid phase transition temperature. Herein, by introducing carbon dots (CDs) with abundant oxygen-related groups, we develop a novel kind of erythritol (ET)-based composite PCMs (CD-ETs) featuring an enhanced latent heat storage capacity and a reduced degree of supercooling compared to pure ETs. The optimally formulated CD-ETs increase the latent heat storage capacity from 377.3 to 410.2 J·g⁻¹ and the heat release capacity from 209.0 to 240.2 J·g⁻¹ compared to the pristine ETs. Moreover, the subcooled degree of CD-ETs is more than 30 °C lower than that of pristine ETs. By successively encapsulating CD-ETs and CD-containing polyethylene glycol (PEG) with a low melting point in a reduced graphene oxide-modified melamine sponge, the resultant shape-stabilized system not only prevents leakage of molten PCMs but also allows for a wide response temperature window and promotes the heat transfer ability of melted PEG in close contact with solid CD-ETs. Stepped melting and crystallization guarantee phase changes in high-melting-point ETs via solar heating, Joule heating or a combination thereof. Specifically, the melting enthalpy of this system is as high as 306.5 J·g⁻¹, and its cold crystallization enthalpy reaches 196.5 J·g⁻¹, surpassing numerous organic PCMs. This work provides a facile and efficient strategy for the design of ideal thermal energy storage materials to meet the needs of application scenarios in a cost-effective manner. Full article