Search Results (174)

430 stainless steel exhibits soft magnetic properties, excellent formability, and corrosion resistance, making it widely used in industrial applications. This study investigates the effects of different cold working rates on the properties of 430 stainless steel subjected to various magnetic annealing atmospheres (F-1.5Si, F-1.5Si-10%, F-1.5Si-40%, F-1.5Si-10% (MA), F-1.5Si-40% (MA), F-1.5Si-10% (H₂), and F-1.5Si-40% (H₂)). The results indicate that increasing the cold working rate improves the material’s mechanical properties; however, it negatively impacts its magnetic and corrosion resistance properties. Additionally, the magnetic annealing process improves the mechanical properties, while atmospheric magnetic annealing optimizes the overall magnetic performance. In contrast, magnetic annealing in a hydrogen atmosphere does not enhance the magnetic properties as effectively as atmospheric magnetic annealing. Still, it promotes the formation of a protective layer, preserving the mechanical properties and providing better corrosion resistance. Furthermore, regardless of whether magnetic annealing is conducted in an atmospheric or hydrogen environment, materials with 10% cold work rate (F-1.5Si-10% (MA) and F-1.5Si-10% (H₂)) exhibit the lowest coercive force (286 and 293 A/m in the 10 Hz test condition), making them ideal for electromagnetic applications. Full article

This study systematically investigated the corrosion evolution and protective mechanisms of X80 pipeline steel in Xinjiang’s saline soil environments under freeze–thaw cycling conditions. Combining regional soil characterization with laboratory-constructed corrosion systems, we employed electrochemical impedance spectroscopy, potentiodynamic polarization, and surface analytical techniques to quantify temporal–spatial corrosion behavior across 30 freeze–thaw cycles. Experimental results revealed a distinctive corrosion resistance pattern: initial improvement (cycles 1–10) attributed to protective oxide layer formation, followed by accelerated degradation (cycles 10–30) due to microcrack propagation and chloride accumulation. Synchrotron X-ray diffraction analyses identified sulfate–chloride ion synergism as the primary driver of localized corrosion disparities in heterogeneous soil matrices. A comparative evaluation of asphalt-coated specimens demonstrated a 62%–89% corrosion rate reduction, with effectiveness directly correlating with coating integrity and thickness (200–500 μm range). Molecular dynamics simulations using Materials Studio revealed atomic-scale ion transport dynamics at coating–substrate interfaces, showing preferential Cl⁻ permeation through coating defects. These multiscale findings establish quantitative relationships between environmental stressors, coating parameters, and corrosion kinetics, providing a mechanistic framework for optimizing protective coatings in cold-region pipeline applications. Full article

Bioactive compounds have shown significant potential in the management of obesity and metabolic syndrome (MetS). This study investigates the effects of antioxidant lipids (ALω-3), synthetized through enzymatic acidolysis using non-specific lipase B from Candida antarctica under supercritical CO₂ conditions. These lipids were derived from a concentrate of rainbow trout (Oncorhynchus mykiss) belly oil, rich in long-chain polyunsaturated omega-3 fatty acids (LCPUFAn-3), and cold-pressed maqui seed oil (MO, Aristotelia chilensis (Mol.) Stuntz). Their effects were then evaluated in a murine high-fat diet (HFD) model. The fatty acid profile, tocopherol and tocotrienol content, and thin-layer chromatography of ALω-3 were analyzed. After 8 weeks on an HFD, male C57BL/6 mice were divided into four groups and switched to a control diet (CD) with the following supplements for 3 weeks: Glycerol (G), commercial marine Omega-3 (CMω-3), a mixture of LCPUFAn-3 concentrate + MO (Mω-3), or ALω-3. The total body and organ weights, serum markers, and liver and visceral fat pro-inflammatory marker expression levels were assessed. ALω-3 contained 13.4% oleic, 33.9% linoleic, 6.3% α-linolenic, 10.7% eicosapentaenoic, and 16.2% docosahexaenoic fatty acids. The β, γ, δ-tocopherol, and β, γ-tocotrienol values were 22.9 ± 1.4, 24.9 ± 0.2, 6.8 ± 0.7, 22.9 ± 1.7, and 22.4 ± 4.7 mg·kg⁻¹, respectively, with α-tocopherol detected in traces. ALω-3 supplementation increased serum Trolox equivalent capacity, significantly reduced serum GPT levels (p < 0.01), and enhanced postprandial glucose tolerance (p < 0.001), although it did not alter insulin resistance (HOMA-IR). These findings indicate ALω-3′s potential for mitigating the glucose intolerance, liver damage, and oxidative stress associated with obesity and MetS, highlighting the need for additional research to explore its potential health benefits. Full article

Modular and prefabricated buildings are advantageous in terms of construction, transport, energy efficiency, fixed costs, and the use of environmentally friendly materials. Our research aims to analyze, evaluate, and optimize a lightweight perimeter structure with an integrated active thermal protection (ATP). We have developed a mathematical–physical model of a wall fragment, in which we have analyzed several variants through a parametric study. ATP in the energy function of a thermal barrier (TB) represents a high potential for energy savings. Cold tap water (an average temperature of +6 °C, thermal untreated) in the ATP layer of the investigated building structure increases its thermal resistance by up to 27.24%. The TB’s mean temperature can be thermally adjusted to a level comparable to the heated space (e.g., +20 °C). For the fragment under consideration, optimizing the axial distance between the pipes (in the ATP layer) and the insulation thickness (using computer simulation) reveals that a pipe distance of 150 mm and an insulation thickness of 100 mm are the most suitable. ATP has significant potential in the design of sustainable, resilient, and climate-adaptive buildings, thereby meeting the UN SDGs, in particular the Sustainable Development Goal 7 ‘Affordable and Clean Energy’ and the Goal 13 ‘Climate Action’. Full article

This study prepared epoxy–clay nanocomposites (ECNs) by incorporating organophilic clays modified with either non-redox cetyltrimethylammonium bromide (CTAB) or redox-active aniline pentamer (AP), then compared their anticorrosion performance on metal substrates in saline environments. The test solution contained 2 wt% alkaline copper quaternary (ACQ) wood preservatives. Cold-rolled steel (CRS) panels coated with the ECNs were evaluated via electrochemical impedance spectroscopy (EIS) in saline media both with and without ACQ. For CRS coated with unmodified epoxy, the Nyquist plot showed impedance dropping from 255 kΩ to 121 kΩ upon adding 2 wt% ACQ—indicating that Cu²⁺ ions accelerate iron oxidation. Introducing 1 wt% CTAB–clay into the epoxy increased impedance from 121 kΩ to 271 kΩ, while 1 wt% AP–clay raised it to 702 kΩ. This improvement arises because the organophilic clay platelets create a more tortuous path for Cu²⁺ and O₂ diffusion, as confirmed by ICP–MS measurements of Cu²⁺ after EIS and oxygen permeability tests (GPA), thereby slowing iron oxidation. Moreover, ECN coatings containing AP–clay outperformed those with CTAB–clay in corrosion resistance, suggesting that AP not only enhances platelet dispersion but also promotes formation of a dense, passive metal oxide layer at the coating–metal interface, as shown by TEM, GPA, and XRD analyses. Finally, accelerated salt-spray exposure following ASTM B-117 yielded corrosion behavior consistent with the EIS results. Full article

Foamed asphalt cold recycled mixtures can provide an effective approach for the reutilization of reclaimed asphalt pavement (RAP), but conventional asphalt foaming technology primarily exploits matrix asphalt as the raw material. To address this issue, this study explores rubberized asphalt with cold recycling technology to develop a foamed rubber asphalt cold recycled mixture (FRCM). The semi-circular bending (SCB) test was employed to investigate its cracking resistance. Load–crack mouth opening displacement (CMOD)–time curves under various temperatures were analyzed, and digital image technique was resorted to monitor crack propagation and growth rates. Fracture toughness, fracture energy, and flexibility index were compared with those of traditional foamed matrix asphalt cold recycled mixture (FMCM). The results show that, under the same test temperature, the FRCM exhibits slower crack propagation; larger peak load; and higher fracture toughness, fracture energy, and flexibility index in comparison with the FMCM. These improvements are more pronounced at low temperatures. For both mixtures, fracture toughness and fracture energy are decreased with increasing the temperature, while the flexibility index shows the opposite trend. The rigid zone accounts for a larger portion of fracture energy at low temperatures. The findings provide technical references for improving the cracking resistance of cold recycled asphalt layers using rubberized asphalt. Full article

Intense ultraviolet (UV) radiation is often accompanied by large temperature differences in high-altitude cold regions. Therefore, investigating the aging behavior of SBR asphalt under intense UV radiation and large temperature differences is crucial for prolonging the lifespan and maintenance of styrene–butadiene rubber (SBR)-modified asphalt pavements in high-altitude cold regions. This study investigated the aging process of SBR-modified asphalt by analyzing the chemical components, microstructures, and micromechanics of both base and SBR-modified asphalt under combined effects. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), gel permeation chromatography (GPC), and atomic force microscopy (AFM) were utilized to analyze this evolutionary process. The results indicated that the chemical components and microstructural properties of the SBR-modified asphalt underwent significant changes during the aging process under the combined effects of intense UV radiation and large temperature differences. The SBR-modified asphalt exhibited the same aging trend for both the chemical composition and microstructure of the matrix asphalt. However, its aging process in the SBR-modified asphalt was notably slower. This delay was primarily caused by the mesh structure of the SBR-modified asphalt, which created an initial buffer period during aging. Additionally, the degradation of SBR replenished the lost components in the asphalt colloid and inhibited the aging process. The research results indicated that the SBR-modified asphalt exhibited superior aging and cracking resistance with respect to the matrix asphalt. However, the critical cracking time for the surface cracks in the SBR-modified asphalt was earlier than that in the matrix asphalt under the combined effects. It was suggested to use the “modulus ratio” (defined as the Young’s modulus ratio of the surface asphalt layer to the underlying asphalt layer) to quantitatively assess the risk of surface cracking, with a higher modulus ratio indicating a greater risk of cracking or a higher degree of cracking. Full article

To investigate the performance degradation of emulsified asphalt cold recycled mixtures (CRM) during service, this study selected a 10 km section of the cold recycled layer (CRL) from the Changjiu Expressway reconstruction project as the research subject. The deterioration patterns of key pavement performance indicators—including the Pavement Condition Index (PCI), Riding Quality Index (RQI), Rutting Depth Index (RDI), and Pavement Structure Strength Index (PSSI)—were analyzed in relation to cumulative equivalent axle loads over a 7-year service period. Concurrently, comparative evaluations were conducted on the mechanical properties, water stability, high-temperature performance, low-temperature crack resistance, and fatigue characteristics between in-service and laboratory-prepared emulsified asphalt CRM. The results demonstrate that after seven years of service, the emulsified asphalt cold recycled pavement maintained excellent performance levels, with PCI, RQI, RDI, and PSSI values of 92.6 (excellent), 90.1 (excellent), 88.5 (good), and 93.4 (excellent), respectively. Notably, while the indirect tensile strength and unconfined compressive strength of the CRL increased with prolonged service duration, other performance metrics—including the tensile strength ratio, shear strength, fracture work, and fracture energy—exhibited an initial improvement followed by gradual deterioration. Additionally, increased traffic loading during service led to a reduction in the residual fatigue life of the CRM. Interestingly, the study observed a temporary improvement in the fatigue performance of CRM during the service period. This phenomenon can be attributed to three key mechanisms: (1) continued cement hydration, (2) secondary hot compaction effects, and (3) diffusion and rejuvenation between fresh and aged asphalt binders. These processes collectively contributed to the partial recovery of aged asphalt strength, thereby improving both the mechanical properties and overall road performance of the CRM. The findings confirm that cold recycled pavements exhibit remarkable durability and maintain a high service level over extended periods. Full article

High-entropy alloys (HEAs), such as the Cantor alloy, are considered for various structural applications owing to their excellent corrosion resistance and high strength at low temperatures, typically below −70 °C, including cryogenic conditions. However, during metalworking, introducing stresses and grain refinement can reduce the corrosion resistance of HEAs. Recrystallization heat treatment relieves these stresses and homogenizes the grain structure, thereby restoring their corrosion resistance and physical properties. However, inadequate heat treatment can result in a microstructure in which coarse and refined grains coexist; thus, the corrosion resistance is diminished and the physical properties are compromised. Therefore, a proper heat treatment is essential for achieving the desired corrosion resistance and mechanical properties of HEAs. In this study, a cold-rolled high-entropy Cantor alloy was subjected to heat treatment for various durations, and the conditions were analyzed. The microstructure and electrochemical behavior were examined. The results indicated that the grains coarsened after a heat treatment time of 5 min and the residual stresses decreased for 15 min. The potential increased from −0.20 to −0.09 V, whereas the resistance of the passive layer increased from 39 to 56 kΩ. These findings confirm that in the Cantor alloy, residual stress reduction and recrystallization begin after 5 min of heat treatment at 1100 °C, which contributes to the recovery of corrosion resistance. The corrosion resistance of the Cantor alloy can be effectively controlled through heat treatment. This underscores the importance of optimizing the heat treatment process in the manufacturing of Cantor alloys. Full article

Expansive soils have significant characteristics of expansion by water absorption, contraction by water loss. Under the freeze–thaw (F-T) cycles, the engineering diseases are more significant, and the serious geotechnical engineering incidents are induced extremely easily. The aim is to investigate the mechanical response characteristics of geogrid-reinforced expansive soils (GRES) under F-T cycles. Based on a series of large-scale temperature-controlled triaxial tests, influencing factors were considered, such as the number of F-T cycles, the geogrid layers, and the confining pressure. The results showed that: (1) Friction between the expansive soil and geogrid and the geogrid’s embedded locking effect indirectly provided additional pressure, limited shear deformation. With the increase in reinforced layers, the stress–strain curve changed from a strain-softening to a strain-hardening type. (2) Elastic modulus, cohesion, and friction angle decreased significantly with increasing number of F-T cycles, whereas dynamic equilibrium was reached after six F-T cycles. (3) The three-layer reinforced specimens showed the best performance of F-T resistance, compared to the plain soil, the elastic modulus reduction amount decreases from 35.7% to 18.3%, cohesion from 24.5% to 14.3%, and friction angle from 7.6% to 4.5%. (4) A modified Duncan–Zhang model with the confining pressure, the F-T cycles, and the geogrid layers was proposed; the predicted values agreed with the measured values by more than 90%, which can be used as a prediction formula for the stress–strain characteristics of GRES under freeze–thaw cycling conditions. The research results can provide important theoretical support for the practical engineering design of GRES in cold regions. Full article

Flow-induced vibration (FIV) characteristics are key factors in enhancing heat transfer. However, challenges such as insufficient heat transfer enhancement and the fatigue strength of the tube bundle persist in the context of improving the heat transfer in elastic tube bundle heat exchangers. This study proposes a novel passive heat transfer enhancement paradigm for elastic tube bundles based on externally induced self-excited oscillations of fluid. By constructing a non-contact energy transfer system, the external oscillation energy is directed into the elastic tube bundle heat exchanger, achieving dynamic stress buffering and breaking through the steady-state flow heat transfer boundary layer. A three-dimensional fluid–structure interaction numerical model is established using Star CCM+2021.3 (16.06.008) to conduct a comparative analysis of the flow characteristics and heat transfer performance between the original structure without an oscillator and the improved structure equipped with a fluid oscillator. The results indicate that the improved structure, through the periodic unsteady jet induced by the fluid oscillator, significantly enhances the turbulence intensity of the shell-side fluid, with the turbulent kinetic energy increasing by over 50%. The radial flow area is notably expanded, thereby reducing the thermal resistance of the boundary layer. At cooling fluid velocities of 6 to 9 m/s, the heat transfer capability of the improved structure is enhanced by more than 50%. Compared with the original structure, the new structure, due to the loading of an external oscillation structure, causes the cold air to present a periodic up and down jet phenomenon. This jet phenomenon, on the one hand, increases the heat exchange area between the cold air and the outer surface of the tube bundle, thereby enhancing the heat exchange capacity. On the other hand, the large-area impact of the fluid reduces the thickness of the boundary layer, lowers the thermal resistance and thereby enhances the heat exchange capacity. Furthermore, this improved structure buffers the mechanical vibrations through self-excited oscillations of the fluid medium, ensuring that the stress levels in the tube bundle remain below the fatigue threshold, effectively mitigating the failure risks associated with traditional active vibration strategies. Full article

This paper investigates the frost heave and thaw settlement characteristics of the pipe–soil system during the freeze–thaw cycle, along with the underlying mechanisms. A numerical simulation platform for the complex pipe–soil system was developed using the heat conduction equation, moisture migration equation, and stress–strain equation, all of which account for the ice–water phase change process. The simulations were performed with the coefficient-type partial differential equation (PDE) module in COMSOL Multiphysics. By employing coupled thermal–hydraulic–mechanical (THM) simulation methods, the study analyzed the changes in volumetric water content, volumetric ice content, moisture migration patterns, and temperature field distribution of a water pipeline after three years of service under real engineering conditions in the cold region of northern Xinjiang, China. The study also examined the effects of parameters such as pipeline burial depth, specific heat capacity, thermal conductivity, permeability of saturated soil, and initial saturation on the displacement field. The results show that selecting soil layers with high specific heat capacity (e.g., 1.68 kJ/kg·°C) and materials with high thermal conductivity (e.g., 2.25 W/m·°C) can reduce surface frost heave displacement by up to 40.8% compared to low-conductivity conditions. The maximum freezing depth near the pipeline is limited to 0.87 m due to the thermal buffering effect of water flow. This research provides a scientific reference and theoretical foundation for the design of frost heave resistance in water pipelines in seasonally frozen regions. Full article

Reflection cracks significantly compromise the service life of half-rigid asphalt pavements in cold regions. This study introduces SAKIII warm-mixed rubber–asphalt mixture (SAKIII WMRA Mix) as a stress absorption layer to address this issue. Through orthogonal tests, regression analysis, and performance comparisons with SBS-modified asphalt, the material composition, low-temperature cracking resistance, and fatigue performance of WMRAM were systematically evaluated. The results show that SAKIII WMRA Mix maintains superior road performance with 30 °C lower mixing/compaction temperatures compared to traditional hot-mix asphalt mixture. At −10 °C, its low-temperature cracking resistance improves by 40% and fatigue life extends by 35% over the SBS-modified asphalt mixture. Mechanistically, SAKIII WMRA Mix reduces reflection crack propagation by 30% and prolongs pavement service life by over 25% under equivalent traffic/climate conditions. Additionally, it decreases energy consumption by 15–20% and provides a sustainable solution for cold-region road construction. This research establishes optimized mix design methods and performance criteria for WMRAM, offering theoretical support and practical guidance for reflective crack mitigation in cold climates. The proposed technology effectively balances mechanical properties, energy efficiency, and environmental benefits, making it especially suitable for cold areas where thermal stress dominates road damage. Full article

This study investigated the formation mechanism of the Kahui Geothermal Field in Western Sichuan, China, using geophysical and geochemical approaches to elucidate its geological structure and geothermal origins. This study employed a combination of 2D and 3D inversion techniques involved in natural electromagnetic methods (magnetotelluric, MT, and audio magnetotelluric, AMT) along with the analysis of hydrogeochemical samples to achieve a comprehensive understanding of the geothermal system. Geophysical inversion revealed a three-layer resistivity structure within the upper 2.5 km of the study area. A geological interpretation was conducted on the resistivity structure model, identifying two faults, the Litang Fault and the Kahui Fault. The analysis suggested that the shallow part of the Kahui Geothermal Field is controlled by the Kahui Fault. Hydrochemical analysis showed that the water chemistry of the Kahui Geothermal Field is of the HCO₃−Na type, primarily sourced from atmospheric precipitation. The deep heat source of the Kahui Geothermal Field was attributed to the partial melting of the middle crust, driven by the upwelling of mantle fluids. This process provides the necessary thermal energy for the geothermal system. Atmospheric precipitation infiltrates through tectonic fractures, undergoes deep circulation and heating, and interacts with the host rocks. The heated fluids then rise along faults and mix with shallow cold water, ultimately emerging as hot springs. Full article

A possible way to solve the problem of energy saving in construction is to introduce energy-efficient buildings at the design stage and, in particular, during retrofit. Therefore, the purpose of this study is to conduct a theoretical analysis of thermal resistance and energy loads on a building in cold climatic conditions. The study of these values was carried out in the ANSYS software package and the Maple computer algebra system, respectively. This study examines four types of structures: the existing facade of a building constructed in 1966, a traditional ventilated facade, and two designs featuring alternating insulation layers with enclosed air channels and with or without heat-reflecting screens in the insulation layer. The results of this study show that the new design incorporating heat-reflecting screens in the insulation layer is 1.15 times more energy-efficient in terms of thermal resistance than the proposed design without such screens. The effectiveness of the proposed new design with heat-reflecting screens in the insulation layer is also confirmed through an analysis of the thermal protection of the building, where the auxiliary indicators, specific characteristics, and complex values of energy efficiency and energy load of the building show greater efficiencies of 1.6, 1.03, and 1.05 times, respectively, compared to the other studied structures. The comprehensive research results presented in this study indicate that the use of energy-efficient wall structures for the retrofit of external enclosures can significantly improve the thermal performance of buildings. It was also determined that the use of such wall structures can significantly enhance the building’s overall energy efficiency rating. The findings of this study highlight that the proposed solutions can contribute to significant energy savings in buildings, while the newly developed structures can serve as valuable additions to the existing catalog of energy-efficient external wall designs. Full article