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Search Results (8,145)

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Keywords = thermal resistances

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12 pages, 2376 KiB  
Article
Investigating Helium-Induced Thermal Conductivity Degradation in Fusion-Relevant Copper: A Molecular Dynamics Approach
by Xu Yu, Hanlong Wang and Hai Huang
Materials 2025, 18(15), 3702; https://doi.org/10.3390/ma18153702 - 6 Aug 2025
Abstract
Copper alloys are critical heat sink materials for fusion reactor divertors due to their high thermal conductivity (TC) and strength, yet their performance under extreme particle bombardment and heat fluxes in future tokamaks requires enhancement. While neutron-induced transmutation helium affects the properties of [...] Read more.
Copper alloys are critical heat sink materials for fusion reactor divertors due to their high thermal conductivity (TC) and strength, yet their performance under extreme particle bombardment and heat fluxes in future tokamaks requires enhancement. While neutron-induced transmutation helium affects the properties of copper, the atomistic mechanisms linking helium bubble size to thermal transport remain unclear. This study employs non-equilibrium molecular dynamics (NEMD) simulations to isolate the effect of bubble diameter (10, 20, 30, 40 Å) on TC in copper, maintaining a constant He-to-vacancy ratio of 2.5. Results demonstrate that larger bubbles significantly impair TC. This reduction correlates with increased Kapitza thermal resistance and pronounced lattice distortion from outward helium diffusion, intensifying phonon scattering. Phonon density of states (PDOS) analysis reveals diminished low-frequency peaks and an elevated high-frequency peak for bubbles >30 Å, confirming phonon confinement and localized vibrational modes. The PDOS overlap factor decreases with bubble size, directly linking microstructural evolution to thermal resistance. These findings elucidate the size-dependent mechanisms of helium bubble impacts on thermal transport in copper divertor materials. Full article
(This article belongs to the Special Issue Advances in Computation and Modeling of Materials Mechanics)
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16 pages, 4746 KiB  
Article
Experimental Study on Millisecond Laser Percussion Drilling of Heat-Resistant Steel
by Liang Wang, Changjian Wu, Yefei Rong, Long Xu and Kaibo Xia
Materials 2025, 18(15), 3699; https://doi.org/10.3390/ma18153699 - 6 Aug 2025
Abstract
Millisecond lasers, with their high processing efficiency and large power, are widely used in manufacturing fields such as aerospace. This study aims to investigate the effects of different processing parameters on the micro-hole processing of 316 heat-resistant steel using millisecond lasers. Through the [...] Read more.
Millisecond lasers, with their high processing efficiency and large power, are widely used in manufacturing fields such as aerospace. This study aims to investigate the effects of different processing parameters on the micro-hole processing of 316 heat-resistant steel using millisecond lasers. Through the control variable method, the study examines the impact of pulse energy, pulse count, and pulse width on the quality of micro-holes, including the entrance diameter, exit diameter, and taper. Furthermore, combined with orthogonal experiments and COMSOL Multiphysics 6.2 simulations, the study explores the influence of pulse width on the formation of blind holes. The experimental results show that when the pulse energy is 2.2 J, the taper is minimal (2.2°), while the taper reaches its peak (2.4°) at 2.4 J pulse energy. As the pulse count increases to 55–60 pulses, the exit diameter stabilizes, and the taper decreases to 1.8°. Blind holes begin to form when the pulse width exceeds 1.2 ms. When the pulse width is 1.2 ms, pulse energy is 2.4 J, and pulse count is 50, the entrance diameter of the blind hole reaches its maximum, indicating that longer pulse widths result in more significant energy reflection and thermal accumulation effects. COMSOL simulations reveal that high-energy pulses cause intense melt ejection, while longer pulse widths exacerbate thermal accumulation at the micro-hole entrance, leading to blind hole formation. This study provides important process references for laser processing of through-holes and blind holes in heat-resistant steel. Full article
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17 pages, 2393 KiB  
Article
Impact of Cu-Site Dopants on Thermoelectric Power Factor for Famatinite (Cu3SbS4) Nanomaterials
by Jacob E. Daniel, Evan Watkins, Mitchel S. Jensen, Allen Benton, Apparao Rao, Sriparna Bhattacharya and Mary E. Anderson
Electron. Mater. 2025, 6(3), 10; https://doi.org/10.3390/electronicmat6030010 - 6 Aug 2025
Abstract
Famatinite (Cu3SbS4) is an earth-abundant, nontoxic material with potential for thermoelectric energy generation applications. Herein, rapid, energy-efficient, and facile one-pot modified polyol synthesis was utilized to produce gram-scale quantities of phase-pure famatinite (Cu2.7M0.3SbS4, [...] Read more.
Famatinite (Cu3SbS4) is an earth-abundant, nontoxic material with potential for thermoelectric energy generation applications. Herein, rapid, energy-efficient, and facile one-pot modified polyol synthesis was utilized to produce gram-scale quantities of phase-pure famatinite (Cu2.7M0.3SbS4, M = Cu, Zn, Mn) nanoparticles (diameter 20–30 nm) with controllable and stoichiometric incorporation of transition metal dopants on the Cu-site. To produce pellets for thermoelectric characterization, the densification process by spark plasma sintering was optimized for individual samples based on thermal stability determined using differential scanning calorimetry and thermogravimetric analysis. Electronic transport properties of undoped and doped famatinite nanoparticles were studied from 225–575 K, and the thermoelectric power factor was calculated. This is the first time electronic transport properties of famatinite doped with Zn or Mn have been studied. All famatinite samples had similar resistivities (>0.8 mΩ·m) in the measured temperature range. However, the Mn-doped famatinite nanomaterials exhibited a thermoelectric power factor of 10.3 mW·m−1·K−1 at 575 K, which represented a significant increase relative to the undoped nanomaterials and Zn-doped nanomaterials engendered by an elevated Seebeck coefficient of ~220 µV·K−1 at 575 K. Future investigations into optimizing the thermoelectric properties of Mn-doped famatinite nanomaterials are promising avenues of research for producing low-cost, environmentally friendly, high-performing thermoelectric materials. Full article
(This article belongs to the Special Issue Feature Papers of Electronic Materials—Third Edition)
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12 pages, 2764 KiB  
Article
AlxCoCrFeNi High-Entropy Alloys Enable Simultaneous Electrical and Mechanical Robustness at Thermoelectric Interfaces
by Xiaoxia Zou, Wangjie Zhou, Xinxin Li, Yuzeng Gao, Jingyi Yu, Linglu Zeng, Guangteng Yang, Li Liu, Wei Ren and Yan Sun
Materials 2025, 18(15), 3688; https://doi.org/10.3390/ma18153688 - 6 Aug 2025
Abstract
The interface between high-performance thermoelectric materials and electrodes critically governs the conversion efficiency and long-term reliability of thermoelectric generators under high-temperature operation. Here, we propose AlxCoCrFeNi high-entropy alloys (HEA) as barrier layers to bond Cu-W electrodes with p-type skutterudite (p-SKD) thermoelectric [...] Read more.
The interface between high-performance thermoelectric materials and electrodes critically governs the conversion efficiency and long-term reliability of thermoelectric generators under high-temperature operation. Here, we propose AlxCoCrFeNi high-entropy alloys (HEA) as barrier layers to bond Cu-W electrodes with p-type skutterudite (p-SKD) thermoelectric materials. The HEA/p-SKD interface exhibited excellent chemical bonding with a stable and controllable reaction layer, forming a dense, defect-free (Fe,Ni,Co,Cr)Sb phase (thickness of ~2.5 μm) at the skutterudites side. The interfacial resistivity achieved a low value of 0.26 μΩ·cm2 and remained at 7.15 μΩ·cm2 after aging at 773 K for 16 days. Moreover, the interface demonstrated remarkable mechanical stability, with an initial shear strength of 88 MPa. After long-term aging for 16 days at 773 K, the shear strength retained 74 MPa (only 16% degradation), ranking among the highest reported for thermoelectric materials/metal joints. Remarkably, the joint maintained a shear strength of 29 MPa even after 100 continuous thermal cycles (623–773 K), highlighting its outstanding thermo-mechanical stability. These results validate the AlxCoCrFeNi high-entropy alloys as an ideal interfacial material for thermoelectric generators, enabling simultaneous optimization of electrical and mechanical performance in harsh environments. Full article
(This article belongs to the Section Metals and Alloys)
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12 pages, 2722 KiB  
Article
Uniform Cu-Based Metal–Organic Framework Micrometer Cubes with Synergistically Enhanced Photodynamic/Photothermal Properties for Rapid Eradication of Multidrug-Resistant Bacteria
by Xiaomei Wang, Ting Zou, Weiqi Wang, Keqiang Xu and Handong Zhang
Pharmaceutics 2025, 17(8), 1018; https://doi.org/10.3390/pharmaceutics17081018 - 6 Aug 2025
Abstract
Background/Objectives: The rapid emergence of multidrug-resistant bacterial infections demands innovative non-antibiotic therapeutic strategies. Dual-modal photoresponse therapy integrating photodynamic (PDT) and photothermal (PTT) effects offers a promising rapid antibacterial approach, yet designing single-material systems with synergistic enhancement remains challenging. This study aims to [...] Read more.
Background/Objectives: The rapid emergence of multidrug-resistant bacterial infections demands innovative non-antibiotic therapeutic strategies. Dual-modal photoresponse therapy integrating photodynamic (PDT) and photothermal (PTT) effects offers a promising rapid antibacterial approach, yet designing single-material systems with synergistic enhancement remains challenging. This study aims to develop uniform Cu-based metal–organic framework micrometer cubes (Cu-BN) for efficient PDT/PTT synergy. Methods: Cu-BN cubes were synthesized via a one-step hydrothermal method using Cu(NO3)2 and 2-amino-p-benzoic acid. The material’s dual-mode responsiveness to visible light (420 nm) and near-infrared light (808 nm) was characterized through UV–Vis spectroscopy, photothermal profiling, and reactive oxygen species (ROS) generation assays. Antibacterial efficacy against multidrug-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was quantified via colony counting under dual-light irradiation. Results: Under synergistic 420 + 808 nm irradiation for 15 min, Cu-BN (200 μg/mL) achieved rapid eradication of multidrug-resistant E. coli (99.94%) and S. aureus (99.83%). The material reached 58.6 °C under dual-light exposure, significantly exceeding single-light performance. Photodynamic analysis confirmed a 78.7% singlet oxygen (1O2) conversion rate. This enhancement stems from PTT-induced membrane permeabilization accelerating ROS diffusion, while PDT-generated ROS sensitized bacteria to thermal damage. Conclusions: This integrated design enables spatiotemporal PDT/PTT synergy within a single Cu-BN system, establishing a new paradigm for rapid-acting, broad-spectrum non-antibiotic antimicrobials. The work provides critical insights for developing light-responsive biomaterials against drug-resistant infections. Full article
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19 pages, 1493 KiB  
Article
Development of Biodegradable Foam Trays from Brewer’s Malt Bagasse and Potato Residues from Agricultural Crops
by Evelyn F. Vásquez-Bacilio, Cesar I. Mejia-Llontop, Carlos E. Tirado-Rodríguez, María de Fátima Arévalo-Oliva, Beetthssy Z. Hurtado-Soria, Eudes Villanueva, Gilbert Rodriguez, Delia Rita Tapia-Blácido and Elza Aguirre
Polymers 2025, 17(15), 2146; https://doi.org/10.3390/polym17152146 - 6 Aug 2025
Abstract
In light of the environmental impact of disposable products made from petroleum-based plastics, this study focused on developing biodegradable foam trays made from a starch (PS) derived from potato waste and beer malt flour (BMBF). The objective of this study was to evaluate [...] Read more.
In light of the environmental impact of disposable products made from petroleum-based plastics, this study focused on developing biodegradable foam trays made from a starch (PS) derived from potato waste and beer malt flour (BMBF). The objective of this study was to evaluate the effect of the concentration of BMBF on the physical and mechanical properties of potato starch-based foam trays prepared by the thermoforming process at temperatures of 150 °C (upper plate) and 145 °C (lower plate) for 5 min and 40 s. The results showed that increasing the BMBF concentration from 0 to 40% reduced the moisture content from 4.68% to 3.42%, increased the thickness from 2.63 cm to 4.77 cm, and decreased the density from 0.28 g.cm−3 to 0.15 g.cm−3. Meanwhile, the water absorption capacity increased from 38.7% to 69.7%. In terms of mechanical properties, increasing the BMBF concentration in the PS foam tray resulted in a decrease in hardness from 5.61 N to 2.87 N, a decrease in tensile strength from 2.92 MPa to 0.85 MPa, and a decrease in elongation from 1.42% to 0.59%. Meanwhile, fracturability increased from 2.04 mm to 3.68 mm. FTIR analysis revealed interactions between BMBF and PS in the composite foam tray. Thermogravimetric analysis (TGA) showed two thermal events: one between 20.96 °C and 172.89 °C, and another between 189.14 °C and 517.69 °C, with weight losses of 5.53% and 74.23%, leaving an ash residue of 20.24%. Differential calorimetry analysis (DSC) showed a glass transition at 152.88 °C and a melting at 185.94 °C, with an enthalpy of fusion of 74.11 J.g−1. Higher concentrations of BMBF (>10%) decreased the water resistance, mechanical strength, and flexibility of the PS foam trays. Therefore, a formulation of 90% PS and 10% BMBF was better for producing a foam tray with improved mechanical properties and water resistance, which could be used as a sustainable alternative to conventional single-use plastic. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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17 pages, 5490 KiB  
Technical Note
Double vs. Single Shear in Dowelled Timber Connections Under Fire Conditions, Thermal Analysis
by Elza M. M. Fonseca
Fire 2025, 8(8), 310; https://doi.org/10.3390/fire8080310 - 5 Aug 2025
Abstract
The main aim of this work is to compare double- or single-designed connections with wooden members and internal steel fasteners under fire conditions. Theoretical methods following Eurocodes will be used to assess the load-bearing capacity of the connections and to compare the effects [...] Read more.
The main aim of this work is to compare double- or single-designed connections with wooden members and internal steel fasteners under fire conditions. Theoretical methods following Eurocodes will be used to assess the load-bearing capacity of the connections and to compare the effects of double and single shear. Several parameters will be examined to determine the load capacity. Furthermore, a numerical thermal analysis using finite element methods will be performed to estimate the temperatures inside the connections and compare them. The results show that the double shear connection in steel-to-timber, with a steel plate of any thickness as the central element and with a higher density of wood material, has better mechanical and fire resistance. Lower temperatures were also observed in this connection type in the wood material and along the length of the dowel. Full article
(This article belongs to the Special Issue Advances in Structural Fire Engineering)
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28 pages, 15022 KiB  
Review
Development and Core Technologies of Long-Range Underwater Gliders: A Review
by Xu Wang, Changyu Wang, Ke Zhang, Kai Ren and Jiancheng Yu
J. Mar. Sci. Eng. 2025, 13(8), 1509; https://doi.org/10.3390/jmse13081509 - 5 Aug 2025
Abstract
Long-range underwater gliders (LRUGs) have emerged as essential platforms for sustained and autonomous observation in deep and remote marine environments. This paper provides a comprehensive review of their developmental status, performance characteristics, and application progress. Emphasis is placed on two critical enabling technologies [...] Read more.
Long-range underwater gliders (LRUGs) have emerged as essential platforms for sustained and autonomous observation in deep and remote marine environments. This paper provides a comprehensive review of their developmental status, performance characteristics, and application progress. Emphasis is placed on two critical enabling technologies that fundamentally determine endurance: lightweight, pressure-resistant hull structures and high-efficiency buoyancy-driven propulsion systems. First, the role of carbon fiber composite pressure hulls in enhancing energy capacity and structural integrity is examined, with attention to material selection, fabrication methods, compressibility compatibility, and antifouling resistance. Second, the evolution of buoyancy control systems is analyzed, covering the transition to hybrid active–passive architectures, rapid-response actuators based on smart materials, thermohaline energy harvesting, and energy recovery mechanisms. Based on this analysis, the paper identifies four key technical challenges and proposes strategic research directions, including the development of ultralight, high-strength structural materials; integrated multi-mechanism antifouling technologies; energy-optimized coordinated buoyancy systems; and thermally adaptive glider platforms. Achieving a system architecture with ultra-long endurance, enhanced energy efficiency, and robust environmental adaptability is anticipated to be a foundational enabler for future long-duration missions and globally distributed underwater glider networks. Full article
(This article belongs to the Section Ocean Engineering)
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31 pages, 13266 KiB  
Article
Emission of Total Volatile Organic Compounds from the Torrefaction Process: Meadow Hay, Rye, and Oat Straw as Renewable Fuels
by Justyna Czerwinska, Szymon Szufa, Hilal Unyay and Grzegorz Wielgosinski
Energies 2025, 18(15), 4154; https://doi.org/10.3390/en18154154 - 5 Aug 2025
Abstract
This study aims to quantify total VOC emissions and evaluate how torrefaction alters the heat of combustion of three agricultural residues. The work examines the amount of VOC emissions during the torrefaction process at various temperatures and investigates the changes in the heat [...] Read more.
This study aims to quantify total VOC emissions and evaluate how torrefaction alters the heat of combustion of three agricultural residues. The work examines the amount of VOC emissions during the torrefaction process at various temperatures and investigates the changes in the heat of combustion of agri-biomass resulting from the torrefaction process. The process was carried out at the following temperatures: 225, 250, 275, and 300 °C. Total VOC emission factors were determined. The reaction kinetics analysis revealed that meadow hay exhibited the most stable thermal behavior with the lowest activation energy. At the same time, rye straw demonstrated higher thermal resistance and complex multi-step degradation characteristics. The authors analyze three types of agricultural biomass: meadow hay, rye straw, and oat straw. The research was divided into five stages: determination of moisture content in the sample, determination of ash content, thermogravimetric analysis, measurement of total VOC emissions from the biomass torrefaction process, and determination of the heat of combustion of the obtained torrefied biomass. Based on the research, it was found that torrefaction of biomass causes the emission of torgas containing VOC in the amount of 2–10 mg/g of torrefied biomass, which can be used energetically, e.g., to support the torrefaction process, and the torrefied biomass shows a higher value of the heat of combustion. Unlike prior studies focused on single feedstocks or limited temperature ranges, this work systematically compares three major crop residues across four torrefaction temperatures and directly couples VOC quantifications. Full article
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14 pages, 2180 KiB  
Article
Study on Preparation of Nano-CeO2 Modified Aluminized Coating by Low Temperature Pack Aluminizing on γ-TiAl Intermetallic Compound
by Jiahui Song, Yunmei Long, Yifan He, Yichen Li, Dianqi Huang, Yan Gu, Xingyao Wang, Jinlong Wang and Minghui Chen
Coatings 2025, 15(8), 914; https://doi.org/10.3390/coatings15080914 (registering DOI) - 5 Aug 2025
Viewed by 40
Abstract
TiAl alloy offers advantages including low density, high specific strength and stiffness, and excellent high-temperature creep resistance. It is widely used in the aerospace, automotive, and chemical sectors, as well as in other fields. However, at temperatures of 800 °C and above, it [...] Read more.
TiAl alloy offers advantages including low density, high specific strength and stiffness, and excellent high-temperature creep resistance. It is widely used in the aerospace, automotive, and chemical sectors, as well as in other fields. However, at temperatures of 800 °C and above, it forms a porous oxide film predominantly composed of TiO2, which fails to provide adequate protection. Applying high-temperature protective coatings is therefore essential. Oxides demonstrating protective efficacy at elevated temperatures include Al2O3, Cr2O3, and SiO2. The Pilling–Bedworth Ratio (PBR)—defined as the ratio of the volume of the oxide formed to the volume of the metal consumed—serves as a critical criterion for assessing oxide film integrity. A PBR value greater than 1 but less than 2 indicates superior film integrity and enhanced oxidation resistance. Among common oxides, Al2O3 exhibits a PBR value within this optimal range (1−2), rendering aluminum-based compound coatings the most extensively utilized. Aluminum coatings can be applied via methods such as pack cementation, thermal spraying, and hot-dip aluminizing. Pack cementation, being the simplest to operate, is widely employed. In this study, a powder mixture with the composition Al:Al2O3:NH4Cl:CeO2 = 30:66:3:1 was used to aluminize γ-TiAl intermetallic compound specimens via pack cementation at 600 °C for 5 h. Subsequent isothermal oxidation at 900 °C for 20 h yielded an oxidation kinetic curve adhering to the parabolic rate law. This treatment significantly enhanced the high-temperature oxidation resistance of the γ-TiAl intermetallic compound, thereby broadening its potential application scenarios. Full article
(This article belongs to the Special Issue High-Temperature Protective Coatings)
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26 pages, 5455 KiB  
Article
Features of Thermal Stabilization of PVC Modified with Microstructured Titanium Phosphate
by Irina N. Vikhareva, Anton Abramian, Dragan Manojlović and Oleg Bol’shakov
Polymers 2025, 17(15), 2140; https://doi.org/10.3390/polym17152140 - 5 Aug 2025
Viewed by 46
Abstract
Poly(vinyl chloride) (PVC) undergoes thermal degradation during processing and operation, which necessitates the use of effective thermal stabilizers. The purpose of this work is to comprehensively evaluate the potential of new hierarchically structured titanium phosphates (TiP) with controlled morphology as thermal stabilizers of [...] Read more.
Poly(vinyl chloride) (PVC) undergoes thermal degradation during processing and operation, which necessitates the use of effective thermal stabilizers. The purpose of this work is to comprehensively evaluate the potential of new hierarchically structured titanium phosphates (TiP) with controlled morphology as thermal stabilizers of plasticized PVC, focusing on the effect of morphology and Ti/P ratio on their stabilizing efficiency. The thermal stability of the compositions was studied by thermogravimetric analysis (TGA) in both inert (Ar) and oxidizing (air) atmospheres. The effect of TiP concentration and its synergy with industrial stabilizers was analyzed. An assessment of the key degradation parameters is given: the temperature of degradation onset, the rate of decomposition, exothermic effects, and the carbon residue yield. In an inert environment, TiPMSI/TiPMSII microspheres demonstrated an optimal balance by increasing the temperature of degradation onset and the residual yield while suppressing the rate of decomposition. In an oxidizing environment, TiPR rods and TiPMSII microspheres provided maximum stability, enhancing resistance to degradation onset and reducing the degradation rate by 10–15%. Key factors of effectiveness include ordered morphology (spheres, rods); the Ti-deficient Ti/P ratio (~0.86), which enhances HCl binding; and crystallinity. The stabilization mechanism of titanium phosphates is attributed to their high affinity for hydrogen chloride (HCl), which catalyzes PVC chain scission, a catalyst for the destruction of the PVC chain. The unique microstructure of titanium phosphate provides a high specific surface area and, as a result, greater activity in the HCl neutralization reaction. The formation of a sol–phosphate framework creates a barrier to heat and oxygen. An additional contribution comes from the inhibition of oxidative processes and the possible interaction with unstable chlorallyl groups in PVC macromolecules. Thus, hierarchically structured titanium phosphates have shown high potential as multifunctional PVC thermostabilizers for modern polymer materials. Potential applications include the development of environmentally friendly PVC formulations with partial or complete replacement of toxic stabilizers, the optimization of thermal stabilization for products used in aggressive environments, and the use of hierarchical TiP structures in flame-resistant and halogen-free PVC-based compositions. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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50 pages, 9033 KiB  
Article
Heat Pipe Integrated Cooling System of 4680 Lithium–Ion Battery for Electric Vehicles
by Yong-Jun Lee, Tae-Gue Park, Chan-Ho Park, Su-Jong Kim, Ji-Su Lee and Seok-Ho Rhi
Energies 2025, 18(15), 4132; https://doi.org/10.3390/en18154132 - 4 Aug 2025
Viewed by 213
Abstract
This study investigates a novel heat pipe integrated cooling system designed for thermal management of Tesla’s 4680 cylindrical lithium–ion batteries in electric vehicles (EVs). Through a comprehensive approach combining experimental analysis, 1-D AMESim simulations, and 3-D Computational Fluid Dynamics (CFD) modeling, the thermal [...] Read more.
This study investigates a novel heat pipe integrated cooling system designed for thermal management of Tesla’s 4680 cylindrical lithium–ion batteries in electric vehicles (EVs). Through a comprehensive approach combining experimental analysis, 1-D AMESim simulations, and 3-D Computational Fluid Dynamics (CFD) modeling, the thermal performance of various wick structures and working fluid filling ratios was evaluated. The experimental setup utilized a triangular prism chamber housing three surrogate heater blocks to replicate the heat generation of 4680 cells under 1C, 2C, and 3C discharge rates. Results demonstrated that a blended fabric wick with a crown-shaped design (Wick 5) at a 30–40% filling ratio achieved the lowest maximum temperature (Tmax of 47.0°C), minimal surface temperature deviation (ΔTsurface of 2.8°C), and optimal thermal resistance (Rth of 0.27°C/W) under 85 W heat input. CFD simulations validated experimental findings, confirming stable evaporation–condensation circulation at a 40% filling ratio, while identifying thermal limits at high heat loads (155 W). The proposed hybrid battery thermal management system (BTMS) offers significant potential for enhancing the performance and safety of high-energy density EV batteries. This research provides a foundation for optimizing thermal management in next-generation electric vehicles. Full article
(This article belongs to the Special Issue Optimized Energy Management Technology for Electric Vehicle)
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20 pages, 7843 KiB  
Article
Effect of Ageing on a Novel Cobalt-Free Precipitation-Hardenable Martensitic Alloy Produced by SLM: Mechanical, Tribological and Corrosion Behaviour
by Inés Pérez-Gonzalo, Florentino Alvarez-Antolin, Alejandro González-Pociño and Luis Borja Peral-Martinez
J. Manuf. Mater. Process. 2025, 9(8), 261; https://doi.org/10.3390/jmmp9080261 - 4 Aug 2025
Viewed by 220
Abstract
This study investigates the mechanical, tribological, and electrochemical behaviour of a novel precipitation-hardenable martensitic alloy produced by selective laser melting (SLM). The alloy was specifically engineered with an optimised composition, free from cobalt and molybdenum, and featuring reduced nickel content (7 wt.%) and [...] Read more.
This study investigates the mechanical, tribological, and electrochemical behaviour of a novel precipitation-hardenable martensitic alloy produced by selective laser melting (SLM). The alloy was specifically engineered with an optimised composition, free from cobalt and molybdenum, and featuring reduced nickel content (7 wt.%) and 8 wt.% chromium. It has been developed as a cost-effective and sustainable alternative to conventional maraging steels, while maintaining high mechanical strength and a refined microstructure tailored to the steep thermal gradients inherent to the SLM process. Several ageing heat treatments were assessed to evaluate their influence on microstructure, hardness, tensile strength, retained austenite content, dislocation density, as well as wear behaviour (pin-on-disc test) and corrosion resistance (polarisation curves in 3.5%NaCl). The results indicate that ageing at 540 °C for 2 h offers an optimal combination of hardness (550–560 HV), tensile strength (~1700 MPa), microstructural stability, and wear resistance, with a 90% improvement compared to the as-built condition. In contrast, ageing at 600 °C for 1 h enhances ductility and corrosion resistance (Rp = 462.2 kΩ; Ecorr = –111.8 mV), at the expense of a higher fraction of reverted austenite (~34%) and reduced hardness (450 HV). This study demonstrates that the mechanical, surface, and electrochemical performance of this novel SLM-produced alloy can be effectively tailored through controlled thermal treatments, offering promising opportunities for demanding applications requiring a customised balance of strength, durability, and corrosion behaviour. Full article
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15 pages, 1706 KiB  
Article
Study on a High-Temperature-Resistant Foam Drilling Fluid System
by Yunliang Zhao, Dongxue Li, Fusen Zhao, Yanchao Song, Chengyun Ma, Weijun Ji and Wenjun Shan
Processes 2025, 13(8), 2456; https://doi.org/10.3390/pr13082456 - 3 Aug 2025
Viewed by 196
Abstract
Developing ultra-high-temperature geothermal resources is challenging, as traditional drilling fluids, including foam systems, lack thermal stability above 160 °C. To address this key technical bottleneck, this study delves into the screening principles for high-temperature-resistant foaming agents and foam stabilizers. Through high-temperature aging experiments [...] Read more.
Developing ultra-high-temperature geothermal resources is challenging, as traditional drilling fluids, including foam systems, lack thermal stability above 160 °C. To address this key technical bottleneck, this study delves into the screening principles for high-temperature-resistant foaming agents and foam stabilizers. Through high-temperature aging experiments (foaming performance evaluated up to 240 °C and rheological/filtration properties evaluated after aging at 200 °C), specific additives were selected that still exhibit good foaming and foam-stabilizing performance under high-temperature and high-salinity conditions. Building on this, the foam drilling fluid system formulation was optimized using an orthogonal experimental design. The optimized formulations were systematically evaluated for their density, volume, rheological properties (apparent viscosity and plastic viscosity), and filtration properties (API fluid loss and HTHP fluid loss) before and after high-temperature aging (at 200 °C). The research results indicate that specific formulation systems exhibit excellent high-temperature stability and particularly outstanding performance in filtration control, with the selected foaming agent FP-1 maintaining good performance up to 240 °C and optimized formulations demonstrating excellent HTHP fluid loss control at 200 °C. This provides an important theoretical basis and technical support for further research and field application of foam drilling fluid systems for deep high-temperature geothermal energy development. Full article
(This article belongs to the Section Energy Systems)
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14 pages, 2448 KiB  
Article
Study on the Semi-Interpenetrating Polymer Network Self-Degradable Gel Plugging Agent for Deep Coalbed Methane
by Bo Wang, Zhanqi He, Jin Lin, Kang Ren, Zhengyang Zhao, Kaihe Lv, Yiting Liu and Jiafeng Jin
Processes 2025, 13(8), 2453; https://doi.org/10.3390/pr13082453 - 3 Aug 2025
Viewed by 208
Abstract
Deep coalbed methane (CBM) reservoirs are characterized by high hydrocarbon content and are considered an important strategic resource. Due to their inherently low permeability and porosity, horizontal well drilling is commonly employed to enhance production, with the length of the horizontal section playing [...] Read more.
Deep coalbed methane (CBM) reservoirs are characterized by high hydrocarbon content and are considered an important strategic resource. Due to their inherently low permeability and porosity, horizontal well drilling is commonly employed to enhance production, with the length of the horizontal section playing a critical role in determining CBM output. However, during extended horizontal drilling, wellbore instability frequently occurs as a result of drilling fluid invasion into the coal formation, posing significant safety challenges. This instability is primarily caused by the physical intrusion of drilling fluids and their interactions with the coal seam, which alter the mechanical integrity of the formation. To address these challenges, interpenetrating and semi-interpenetrating network (IPN/s-IPN) hydrogels have gained attention due to their superior physicochemical properties. This material offers enhanced sealing and support performance across fracture widths ranging from micrometers to millimeters, making it especially suited for plugging applications in deep CBM reservoirs. A self-degradable interpenetrating double-network hydrogel particle plugging agent (SSG) was developed in this study, using polyacrylamide (PAM) as the primary network and an ionic polymer as the secondary network. The SSG demonstrated excellent thermal stability, remaining intact for at least 40 h in simulated formation water at 120 °C with a degradation rate as high as 90.8%, thereby minimizing potential damage to the reservoir. After thermal aging at 120 °C, the SSG maintained strong plugging performance and favorable viscoelastic properties. A drilling fluid containing 2% SSG achieved an invasion depth of only 2.85 cm in an 80–100 mesh sand bed. The linear viscoelastic region (LVR) ranged from 0.1% to 0.98%, and the elastic modulus reached 2100 Pa, indicating robust mechanical support and deformation resistance. Full article
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