Search Results (92)

With the rapid development of wearable electronics, traditional rigid thermal management materials face limitations in flexibility, conformability, and multi-physics adaptability. Low-dimensional carbon materials such as graphene and carbon nanotubes combine ultrahigh thermal conductivity with outstanding mechanical compliance, making them promising building blocks for flexible thermal regulation. This review summarizes recent advances in integrating these materials into textile architectures, mapping the evolution of this emerging field. Key topics include phonon-dominated heat transfer mechanisms, strategies for modulating interfacial thermal resistance, and dimensional effects across scales; beyond these intrinsic factors, hierarchical textile configurations further tailor macroscopic performance. We highlight how one-dimensional fiber bundles, two-dimensional woven fabrics, and three-dimensional porous networks construct multi-directional thermal pathways while enhancing porosity and stress tolerance. As for practical applications, the performance of carbon-based textiles in wearable systems, flexible electronic packaging, and thermal coatings is also critically assessed. Current obstacles—namely limited manufacturing scalability, interfacial mismatches, and thermal performance degradation under repeated deformation—are analyzed. To overcome these challenges, future studies should prioritize the co-design of structural and thermo-mechanical properties, the integration of multiple functionalities, and optimization guided by data-driven approaches. This review thus lays a solid foundation for advancing carbon-based smart textiles toward next-generation flexible thermal management technologies. Full article

The thermal conductivity of steel is high compared to other materials such as concrete or timber. Therefore, fire protection measures are applied to prolong the duration between the onset of fire exposure and the final loss of load-bearing function of a steel structure. The most common passive fire protection measure is the application of intumescent coating (IC), a thin film that expands at elevated temperatures and forms an insulating char layer of lower thermal conductivity. This paper focuses on structural steel beams with IPE open-section profiles protected by a water-based IC and subjected to static and standard fire loading. ANSYS 16.0 is used to simulate heat transfer, with thermal conductivity function described by standard multivariate linear regression analysis, followed by mechanical analysis considering degradation of material mechanical properties at elevated temperatures. Simulations are conducted for all IPE profile sizes, with varying initial degrees of utilisation, beam lengths, and coating thicknesses. Results indicated fire resistance times ranging from 24 to 53.5 min, demonstrating a relatively good level of fire resistance even with the minimal IC thickness. Furthermore, artificial neural networks were developed to predict the fire resistance time of steel members with IC using varying numbers of hidden neurons and subset ratios. The model achieved a predictability level of 99.9% upon evaluation. Full article

Low-temperature radiant heating systems utilizing heating cables face challenges including low heat dissipation efficiency and high energy consumption, hindering widespread application. Graphene coatings, characterized by high thermal conductivity and far-infrared radiation properties, offer a novel approach to enhance cable heat dissipation efficiency. This study systematically investigates the effects of coating position, thickness, and ambient temperature on cable heat dissipation using numerical simulations and experiments. A three-dimensional heat transfer model of the heating cable was established using Fluent software (2022R1). The radiation heat transfer equation was solved using the Discrete Ordinates (DO) model, and the coating position and thickness parameters were optimized. The reliability of the simulation results was validated using a temperature-rise experimental platform. The results indicate that graphene coatings significantly improve the heat dissipation performance of cables. Under optimal parameters (coating thickness: 100 μm, coating position: aluminum fin surface, initial temperature: 5 °C), the heat flux increased by approximately 26%, aluminum fin surface temperature decreased to 41.5 °C, and experimental temperature-rise efficiency improved by nearly 50%. The discrepancy between simulated and experimental results was within 8.5%. However, when coating thickness exceeded 100 μm, interfacial thermal resistance increased, reducing heat dissipation efficiency. Additionally, higher ambient temperatures suppressed heat dissipation. These findings provide a theoretical basis for optimizing the energy efficiency of low-temperature radiant heating systems. Full article

This study explores how production technology influences spray-applied rigid polyurethane (PUR) foam insulation’s cryogenic performance. In cryogenic applications such as liquid gas storage, insulation must minimise heat transfer and resist moisture ingress under severe thermal gradients. Experimental aluminium vessels were insulated with PUR foam of varying thicknesses and surface conditions—rough, machined smooth, and with a urea-based protective coating—and then tested using dynamic boil-off of liquid nitrogen (LN₂). Foam properties, including adhesion, mechanical strength, thermal expansion, thermal conductivity, and closed-cell content, were evaluated. The results revealed that thicker insulation reduced both effective thermal conductivity and moisture uptake. Although the urea-coated vessel showed minimal water absorption, the coating increased overall thermal conductivity due to its heat conduction and condensation behaviour. Moisture was primarily absorbed near the foam surface, and no cumulative effects were observed during repeated tests. The effective thermal conductivity was determined by interpolating boil-off data, confirming that insulation performance strongly depends on thickness, surface condition, and environmental humidity. These findings provide valuable guidance for the design and application of PUR foam insulation in cryogenic environments. Full article

This study investigated the thermal performance of reduced super intumescent (RSI) coating, focusing on the correlation between porosity evolution and thermal conductivity under elevated temperature conditions. Porosity development was quantified using scanning electron microscopy (SEM) combined with MATLAB-based image analysis, achieving a maximum porosity of 62% after 60 min of exposure. Thermal degradation was characterized using thermogravimetric analysis (TGA), which recorded a mass loss of 35% between 250 °C and 400 °C, capturing the decomposition kinetics and correlating degradation stages with char formation. Fire protection efficiency was evaluated by employing heat flow meter tests (thermal conductivity reduced from 0.15 W/mK to 0.05 W/mK), methane torch experiments (backside temperature increase delayed by up to 50% compared to uncoated steel), and COMSOL-based heat transfer simulations. The results revealed that the RSI coating’s thermal conductivity decreased as its porosity increased, enhancing its insulation effectiveness. Additionally, the formation of a thermally stable char layer at 400 °C significantly reduced heat transfer to the metal substrate by 66%. These findings support the optimization of bio-derived fire-retardant coatings for passive fire protection applications. Full article

This study focused on developing a color-changing fabric face mask for fever detection. Reversible Thermochromic Leuco dye (RTL) was applied as an indicator to alert wearers of elevated body temperatures, with the color change occurring at 37.5 °C. Five fabric types Polyethylene (PE), cotton (CO), a cotton–polyester blend (TC), polyester (PL), and Polyamide (PA) were coated with blue RTL to evaluate their color change responsiveness. The results showed that fabrics with higher thermal conductivity (λ), thermal absorptivity (b), and heat flow (q) exhibited faster color transitions. RTL-coated PE fabric demonstrated the best performance, with a thermal absorptivity of 312.8 Ws^0.5m⁻²K⁻¹ and a heat flow of 2.11 Wm⁻², leading to a rapid color-change time of approximately 4.20 s. Although PE fabric had a lower thermal conductivity (57.6 × 10⁻³ Wm⁻¹K⁻¹) compared to PA fabric 84.56 (10⁻³ Wm⁻¹K⁻¹), the highest thickness 0.65 mm of PA fabric slowed its color-change reaction to 11.8 s. When selecting fabrics for optimal heat transfer, relying solely on fiber type or thermal conductivity (λ) is insufficient. The fabric’s structural properties, particularly thickness, significantly impact thermal resistance (γ). Experimental results suggest that thermal absorptivity and heat flow are more effective criteria for fabric selection, as they directly correlate with color-change performance. Full article

The prevailing fire-resistant design of steel structures typically relies on the premise of localized heating, whereas the overall temperature increase resulting from the dispersion of hot smoke is frequently oversimplified. These theoretical simplifications may result in considerable structural safety risks. This research utilized the Transient Thermo-Mechanical Coupling Theory and developed a double-layer steel frame finite element model using ABAQUS 2023 software. The simulation of multi-physics field coupling involving smoke convection-radiation heat transfer and nonlinear structure response in fire situations was accomplished by establishing 24 sets of comparative conditions over three distinct premises. Upon comparing the conditions with the greatest displacement values across the three situations, it was concluded that when hot smoke is produced in the initial room, it commences diffusion into adjacent rooms both horizontally and vertically. In comparison to the scenario that disregards the dispersion of hot smoke, the displacement of the components escalated by 342.3%. The dispersion of hot smoke reveals that the displacement of components in the center room of the fire’s origin was 23.1% greater than in the corner room, while the displacement in the second-story room was 115.6% greater than in the first-story room. The use of fireproof coating markedly diminished component displacement in the context of hot smoke dispersion, achieving an 82.8% reduction in displacement among components in identical positions. The enhanced vulnerability model augmented the precision of forecasting the ongoing failure of steel frames by 29.1%. Full article

Square steel tube (SST) columns are widely applied, and fire resistance is a critical issue in its design. Current research on the fire resistance of the SST column predominantly assumes that it is uniformly exposed to fire, ignoring the thermal insulation of the surrounding walls under actual fire conditions. The heat transfer and mechanical finite element model (FEM) for SST columns embedded in walls under an ISO 834 standard fire are established in this study, and the accuracy of the FEM is verified by existing experimental results. Subsequently, the wall effect on the temperature distribution and fire resistance of the SST columns exposed to fire is analyzed, the stress mechanisms of the SST column embedded in walls is investigated and further parametric analyses are performed. The results show that, for SST columns embedded in walls, the temperature rise rate of the wall-embedded region is significantly reduced, and the fire resistance is improved by 25.3% compared with the case of uniform exposure to fire. Under two fire conditions, the SST columns exhibit compressive bending failure, and when considering the wall effect, the uneven temperature distribution induces material strength eccentricity, causing the buckling direction to deviate toward the wall-thickness direction. Reducing the fire-resistive coating thickness of the wall-embedded region can mitigate the uneven stress distribution, thereby lowering construction costs while concurrently preserving fire resistance. Increasing the steel tube thickness can significantly improve the fire resistance, but the high steel strength and slenderness ratio result in the accelerated failure of the SST column when exposed to fire. Full article

In the context of the global energy structure transformation, concentrated solar power (CSP) technology has gained significant attention. Its future trajectory is oriented towards the construction of ultra-high temperature (700–1000 °C) power plants, aiming to enhance thermoelectric conversion efficiency and economic competitiveness. Chloride molten salts, serving as a crucial heat transfer and storage medium in the third-generation CSP system, offer numerous advantages. However, they are highly corrosive to metal materials. This paper provides a comprehensive review of the corrosion behaviors of stainless steels and high-temperature alloys in molten salts. It analyzes the impacts of factors such as temperature and oxygen, and it summarizes various corrosion types, including intergranular corrosion and hot corrosion, along with their underlying mechanisms. Simultaneously, it presents an overview of the types, characteristics, impurity effects, and purification methods of molten salts used for high-temperature heat storage and heat transfer. Moreover, it explores novel technologies such as alternative molten salts, solid particles, gases, liquid metals, and the carbon dioxide Brayton cycle, as well as research directions for improving material performance, like the application of nanoparticles and surface coatings. At present, the corrosion of metal materials in high-temperature molten salts poses a significant bottleneck in the development of CSP. Future research should prioritize the development of commercial alloy materials resistant to chloride molten salt corrosion and conduct in-depth investigations into related influencing factors. This will provide essential support for the advancement of CSP technology. Full article

The growing intensity and frequency of bushfires across the globe pose serious threats to building safety when it comes to the vulnerability of glass windows. During bushfires, extreme heat can cause significant damage to these windows, creating openings that allow embers, radiant heat, and flames to enter buildings. This study investigated the effectiveness of various construction materials, including thin steel sheets, glass fibre blankets, aluminium foil layers, and intumescent layers on glass fibre blankets, as bushfire-resistant shutters for protecting windows in bushfire-prone areas. The shutters were tested under two scenarios of radiant heat exposure: rapid and prolonged exposures of 11 and 47 min, respectively. Heat transfer models of the tested shutters were developed and validated using fire test results, and then comparisons of the performance of materials were made through parametric studies for bushfire radiant heat exposure. The results show that a 0.4 mm glass fibre blanket with aluminium foil performed best, with very low glass temperatures and ambient heat fluxes due to the reflective properties of the foil. Similarly, a thin steel sheet (1.2 mm) also effectively maintained low glass temperatures and ambient heat fluxes. Additionally, graphite-based intumescent coating on a glass fibre blanket reduced the ambient heat flux. These results highlight the importance of bushfire-resistant shutters and provide valuable insights for improving their design and performance. Full article

Friction surfacing (FS) is a solid-state process for depositing metallurgically bonded coatings for corrosion and wear protection. It is particularly attractive for depositing coatings in materials that are difficult to fusion deposit. Stellite 6 is one such material, which is widely used as a protective coating on steel structures to combat wear and corrosion. In the current study, Stellite 6 was successfully friction-surfaced on low carbon steel plates without using any preheating. The microstructures and wear behavior of Stellite 6 coatings produced using FS were comparatively investigated with those produced using the plasma transferred arc (PTA) process. The PTA coatings showed a cast microstructure consisting of γ-dendrites and an inter-dendritic carbide network. On the other hand, the FS coatings showed a wrought microstructure with dynamically recrystallized grains and fine, uniformly distributed carbide particles. The FS coatings also showed uniform composition across the coating thickness and were undiluted, while the PTA coatings showed significant dilution as well as strong local variations in chemistry. The FS coatings exhibited a 22% increase in hardness (550 HV) compared to the PTA coatings (450 HV). Pin-on-disc dry sliding wear tests showed that the FS coatings (1.205 mm³) were more wear resistant compared to the PTA coatings (6.005 mm³), highlighting their superior mechanical performance. This study uniquely demonstrates the feasibility of depositing Stellite 6 coatings using FS without the need for preheating or post-deposition heat treatments, while achieving superior microstructural refinement, hardness, and wear resistance compared to conventional PTA coatings. Full article

Design under uncertainty has significantly grown in research developments during the past decade. Additionally, machine learning (ML) and explainable ML (XML) have offered various opportunities to provide reliable predictable models. The current article investigates the use of finite element modeling (FEM), ML and XML predictions, and uncertain-based design of carbon-carbon (C-C) composites for use in ultra-high temperatures. A C-C composite concentrating solar power (CSP) as a microvascular receiver is considered as a case study. These C-C composites are fiber composites with directly integrated carbonized microchannels to form a lightweight, high-absorptivity material that includes an embedded microvascular network of channels. The topology of these microchannels is engineered to optimize heat transfer to a supercritical carbon dioxide (sCO₂) heat transfer fluid. The mechanical characterization of C-C composites is highly challenging. Thus, designing every component made of C-C composites for ultra-high temperature applications needs an uncertainty-based analysis. As a part of a comprehensive project on the development of a novel carbonized microvascular C-C composite, this paper explores C-C composite sensitivity analysis, FEM, ML prediction, and XML analysis. The resulting composite can then be carbonized and coated with an oxidation-resistant coating to form a thermally efficient and mechanically robust C-C composite. An ANSYS 3-D-FE model was used to analyze the CSP’s stress/strain. To consider the variability in the mechanical and thermal properties of C-C composites, various mechanical properties are considered as the ANSYS FEM’s input. A synthetic dataset from 730 ANSYS runs was produced to feed into the ML and XML algorithms for uncertainty analysis and prediction. The ML and XML algorithms could accurately predict the CSP stresses/strains. Full article

Geopolymers have emerged as promising materials for their superior thermal and mechanical properties, offering sustainable alternatives to conventional coatings. This study investigates the potential of Palm Oil Fuel Ash (POFA) as a raw material for fire-resistant geopolymer coatings. Through the optimization of POFA-to-alkaline activator (AA) ratios, NaOH concentrations, and curing temperatures, POFA-based coatings were synthesized and applied to mild steel substrates. Fire resistance testing revealed that the optimal formulation (0.35 POFA ratio, 8 M NaOH concentration, and curing at 65 °C) achieved a temperature at equilibrium (TAE) of 151.2 °C, significantly outperforming other compositions by reducing heat transfer during fire exposure. Thermal imaging and SEM analysis demonstrated that the optimized coating (GP-POFA8) exhibited a more uniform and stable intumescent layer, leading to lower peak temperatures (909 °C) compared to less optimized samples. Thermogravimetric Analysis (TGA) further confirmed that GP-POFA8 retained approximately 80% of its original mass at temperatures beyond 600 °C, highlighting its superior thermal stability. These findings underscore the potential of POFA-based geopolymers as effective, eco-friendly solutions for fire-resistant applications in construction and industrial sectors, contributing to sustainable waste management. Full article

Overlaying welding is a technology that allows for the acquisition of structural materials with advantageous and complex operating properties. The substrate material can be a material with advantageous mechanical and plastic properties, and the coating can provide corrosion or abrasion (wear) resistance. Among coating application techniques, plasma transfer arc (PTA) overlay welding can be used, where the overlay ensures metallic continuity and high durability, but is a limitation in the joining technologies. Therefore, research was carried out on the possibility of making Co-rich PTA overlay welding coatings on duplex steel, which combine the unique properties of duplex steel and the abrasion resistance of the coating. The tests performed showed that it is possible to apply a coating on the edges of elements without unfavorable changes in the material associated with the formation of carbides and the sigma phase in the HAZ. The coating has a structure of a Co-rich solid solution and a net of eutectics with carbide precipitations. This allowed for high hardness (600 HV10) without the need for additional heat treatment procedures. Full article

Copper, though highly conductive, requires improved wear resistance and thermal dissipation in applications that involve continuous movement and current-induced vibrations, such as power breakers. Conventional solutions, such as copper–tungsten alloys or lubricant use, face limitations in durability, friction, or environmental impact. This study explores the development of copper–graphene (Cu-GNPs) composite coatings using pulsed electrodeposition to enhance the tribological, thermal, and mechanical properties of circuit breaker components by adopting an industrially scalable technique. The influence of deposition bath temperature, duty cycle, and frequency on coating morphology, hardness, wear resistance, and heat dissipation was systematically evaluated using a 2³ full factorial design and an Analysis of Variance (ANOVA). The results revealed that optimized pulsed electrodeposition significantly improved coating performance: hardness increased by 76%, wear volume decreased by more than 99%, and friction coefficient stabilized at 0.2, reflecting effective graphene integration. The addition of graphene further improved thermal diffusivity by 19.5%, supporting superior heat dissipation. These findings suggest that pulsed copper–graphene composite coatings offer a promising alternative to traditional copper alloys, enhancing the lifespan and reliability of electronic components through improved wear resistance, lower friction, and superior heat transfer. Full article