The effect of aging on the mechanical properties of the 2195-T34 Al−Li alloy at different stress levels was investigated. When the stress was below the high-temperature yield strength (YS), the YS and elongation (EL) of the low-stress aged (LSA) and stress-free aged (SFA) specimens were similar. When the stress exceeded the high-temperature YS, the ultimate tensile stress (UTS) and EL of the specimens (HSA specimens) decreased significantly. This decrease suggested that an increase in stress reduced the damage resistance of the material. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations showed that variations in the effect of stress on the material properties were attributed to the combined effect of internal precipitate characteristics and Cu-rich precipitates at the grain boundary. The increase in stress induced the segregation of Cu atoms at the grain boundaries to form Cu-rich precipitates, facilitating the formation of precipitation-free zones (PFZ) at the grain boundaries. In addition, Cu-rich precipitates could act as damage nucleation sites, reducing the ductility of the material.

The aggregation of low-dimensional nanofillers in the host ceramic matrix significantly discounted their reinforcing efficiency. Herein, employing two-dimensional graphene (G) and one-dimensional SiC nanowire (SiC_nw), WC-G-SiC_nw ceramic composites were prepared through spark plasma sintering. The effects of sintering temperature, soaking time and pressure on the mechanical properties of the WC-based composites were reported. The influence of graphene and SiC_nw on the densification, microstructure and mechanical properties of the ceramic composites were investigated. The experimental results demonstrated that excellent mechanical properties were achieved for WC-0.15 wt.% G–0.45 wt.% SiC_nw prepared through sintering at 1900 °C for 15 min holding time and 60 MPa pressure, with a hardness of 25.6 GPa, a flexural strength of 1499 MPa and a fracture toughness of 11.6 MPa·m^1/2. The toughening mechanisms were mainly the combination of G and SiC_nw induced crack deflection, bridging and pullout. This study provided a simple toughening method in developing high-performance ceramic composites.

To study the effect of liquid cooling, including acid cooling and water cooling, on the microscopic characteristics of high-temperature granite, scanning electron microscopy and energy spectroscopy analysis tests (SEM-EDS) as well as mercury injection experiments were carried out on liquid-cooled granite. The SEM-EDS results show that the elemental composition is barely affected by water cooling, while acid cooling causes reductions in O, Si, and metallic elements. The pores and cracks were observed in both cases. Moreover, a more non-flat, loose, and rough surface is created under acid cooling conditions compared to water cooling. Mercury injection tests show an increase in porosity, pore volume, and specific surface area in liquid-cooled granite samples, while their fractal dimensions show an opposite trend. Acid cooling leads to significantly greater property changes than water cooling, owing to the dissolution effects of mud acid. The results demonstrate that the acid cooling process results in greater capacity of pore generation and expansion, as well as lower pore structure complexity, compared to water cooling.

The novel CO₂ static blasting method offered good prospects for application as it was more effective than mechanical rock breaking, less vibratory, less dusty and quieter than the traditional drill and blast method. We carried out both true triaxial CO₂ static blasting fracturing experiments and rock-breaking site vibration monitoring experiments to extract vibration signal characteristics, focusing on slope safety. The results show that: 1) the peak vibration velocity of CO₂ static blasting decayed rapidly and dropped below 30 mm/s at 6 m; 2) the principal frequency of the vibration waveform spectrum caused by CO₂ static blasting was higher than that of the drill-and-blast method; 3) the vibration velocity prediction formula used in the drill-and-blast method was applicable to CO₂ static blasting, and the prediction formula with elevation was more accurate. An HIG fracturing model for CO₂ static blasting is proposed, which provides a basic framework for research of new rock-breaking techniques. The vibration displacement of the slope under CO₂ static blasting is minimal, and more attention should be paid to the exothermic and temperature measurement of the polyenergy agent in the future.

This study aims to simulate pulsatile blood flow in the carotid artery with different stenosis severities and pulse rates. The effects of different severities of stenosis, pulse rates, and arterial wall properties on the surrounding fluid are investigated by using fluid-structure interaction (FSI) and arbitrary Lagrangian-Eulerian (ALE) methods. Carreau-Yasuda non-Newtonian and modified Mooney-Rivin hyperelastic models are applied for blood with non-Newtonian behavior and hyperelastic blood vessel’s wall, respectively. Results are presented in terms of wall radial displacement, pressure distribution, the axial velocity profile, and wall shear stress for blood. By increasing the stenosis severities, there would be a change in several parameters. Axial velocity, variation of blood pressure, the maximum wall shear stress, and wall radial displacement experience a growth. Furthermore, when the pulse rate grows in the stenosis severity of 75%, the maximum flow rate moments, maximum values for wall radial displacement, pressure, axial velocity, and wall shear stress increase as well. Using a hyperelastic model for the arterial wall, as opposed to elastic and rigid models, and treating the surrounding fluid as non-Newtonian and unsteady, allows us to achieve a more realistic simulation. In the stenosis having up to 50% of severity, red blood cells are under the enforcement of insignificant damage, while hemolysis is observed in the severe stenosis of 75%. By improving atherosclerosis, which leads to the development of elastic modulus from 500 kPa to 2 MPa, the 65% growth of the maximum value of shear stress at 60 bpm pulse rate and in the stenosis with 75% severity has been noticed. It can be demonstrated that hyperelastic models of the arterial walls lead to lower axial velocity, lower blood pressure, lower shear stress, and higher radial displacement, as opposed to rigid and elastic arterial walls.

Superhydrophobic surfaces have attracted considerable interest due to their various functions and wide applications. Most of the existing methods for preparing superhydrophobic surfaces are only applicable to one or several specific substrate materials, which have the disadvantage of substrate-dependent. Here, an approach for the fabrication of substrate-independent superhydrophobic surfaces based on femtosecond laser-chemical hybrid processing is proposed. Micro/nanostructures are constructed on substrates via femtosecond laser direct writing technology, followed by modification with stearic acid. The laser-treated samples coated with stearic acid (LTx-SA, x presents different samples) surfaces have excellent superhydrophobic and self-cleaning properties. Moreover, it is worth noting that the LTx-SA surfaces remain stable superhydrophobicity after heating substrate from 20 °C to 100 °C, washing substrate 10 times, and exposing substrate to air for 60 days. This work provides an efficient and facile strategy for achieving substrate-independent superhydrophobic surfaces.

Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness. The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials. This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years. The emergence of new raw material, the advancement of perparation methods and manufacturing techniques, and the potential applications of permanent ferrite materials are introduced and discussed. Specifically, nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources, and therefore it could be a promising development trendency.

As an industrial byproduct of smelter operations, smelting slag has brought certain environmental issues including without taking safety precautions or using appropriate management. Through a thorough analysis of the literature published in the last years, the latest research progress on the characteristics, resource utilization pathways, and safety utilization evaluation of non-ferrous metal smelting slag was introduced in this work. Key findings indicate that different ore concentrate materials, smelting conditions and types determine chemical and mineralogical characteristics of smelting slag. Moreover, smelting slag exhibits extremely high flexibility in various applications, not only as metal recovery and construction materials, but also as agricultural fertilizers and remediation agents. At the same time, the importance of conducting strict safety assessments under various utilization scenarios to mitigate its potential environmental risks is emphasized. In addition, this article also emphasizes the direction of future research, including creating a comprehensive and quantized environmental risk assessment method of heavy metals in soil-slag mixtures, as well as exploring more innovative utilization methods of smelting slag. Overall, this review is significant for promoting research on the use of smelting slag in environmental protection and sustainable resource utilization.

Exploitation of sustainable energy sources requires the use of unique conversion and storage systems, such as solar panels, batteries, fuel cells, and electronic equipment. Thermal load management of these energy conversion and storage systems is one of their challenges and concerns. In this article, the thermal management of these systems using thermoelectric modules is reviewed. The results show that by choosing the right option to remove heat from the hot side of the thermoelectric modules, it will be a suitable local cooling, and the thermoelectric modules increase the power and lifespan of the system by reducing the spot temperature. Thermoelectric modules were effective in reducing panel temperature. They increase the time to reach a temperature above 50 °C in batteries by 3 to 4 times. Also, in their integration with fuel cells, they increase the power density of the fuel cell.

Wire-arc additive manufacture (WAAM) has great potential for manufacturing of Al-Cu components. However, inferior mechanical properties of WAAM deposited material restrict its industrial application. Inter-layer cold rolling and thermo-mechanical heat treatment (T8) with pre-stretching deformation between solution and aging treatment were adopted in this study. Their effects on hardness, mechanical properties and microstructure were analyzed and compared to the conventional heat treatment (T6). The results show that cold rolling increases the hardness and strengths, which further increase with T8 treatment. The ultimate tensile strength (UTS) of 513 MPa and yield stress (YS) of 413 MPa can be obtained in the inter-layer cold-rolled sample with T8 treatment, which is much higher than that in the as-deposited samples. The cold-rolled samples show higher elongation than that of as-deposited ones due to significant elimination of porosity in cold rolling; while both the T6 and T8 treatments decrease the elongation. The cold rolling and pre-stretching deformation both contribute to the formation of dense and dispersive precipitated θ′ phases, which inhibits the dislocation movement and enhances the strengths; as a result, T8 treatment shows better strengthening effect than the T6 treatment. The strengthening mechanism was analyzed and it was mainly related to work hardening and precipitation strengthening.

One of the challenges for bimetal manufacturing is the joining process. Hence, transient liquid phase (TLP) bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75 µm for bonding time of 20, 40, 60, and 90 min. The bonding temperature of 860 °C was considered, which is under the β transus temperature of Cp-Ti. During TLP bonding, various intermetallic compounds (IMCs), including Ti₅Cr₇Fe₁₇, (Cr, Fe)₂Ti, Ti(Cu, Fe), Ti₂(Cu, Ag), and Ti₂Cu from 304L toward Cp-Ti formed in the joint. Also, on the one side, with the increase in time, further diffusion of elements decreases the blocky IMCs such as Ti₅Cr₇Fe₁₇, (Cr, Fe)₂Ti, Ti(Cu, Fe) in the 304L diffusion-affected zone (DAZ) and reaction zone, and on the other side, Ti₂(Cu, Ag) IMC transformed into fine morphology toward Cp-Ti DAZ. The microhardness test also demonstrated that the (Cr, Fe)₂Ti + Ti₅Cr₇Fe₁₇ IMCs in the DAZ on the side of 304L have a hardness value of HV 564, making it the hardest phase. The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa, respectively. The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.

Due to the long-term plate tectonic movements in southwestern China, the in-situ stress field in deep formations is complex. When passing through deep soft-rock mass under non-hydrostatic high in-situ stress field, tunnels will suffer serious asymmetric deformation. There is no available support design method for tunnels under such a situation in existing studies to clarify the support time and support stiffness. This study first analyzed the mechanical behavior of tunnels in non-hydrostatic in-situ stress field and derived the theoretical equations of the ground squeezing curve (GSC) and ground loosening curve (GLC). Then, based on the convergence confinement theory, the support design method of deep soft-rock tunnels under non-hydrostatic high in-situ stress field was established considering both squeezing and loosening pressures. In addition, this method can provide the clear support time and support stiffness of the second layer of initial support. The proposed design method was applied to the Wanhe tunnel of the China-Laos railway in China. Monitoring data indicated that the optimal support scheme had a good effect on controlling the tunnel deformation in non-hydrostatic high in-situ stress field. Field applications showed that the secondary lining could be constructed properly.

In this study, the dynamic stress concentration factors (DSCF) around a straight-wall arch tunnel (SWAT) were solved analytically utilizing the complex variable function methods and Duhamel’s integral. The effects of wavelength, incident angle, and blasting rising time on the DSCF distribution were analyzed. Theoretical results pointed out dynamic disturbances resulting in compressive stress concentration in the vertical direction and tensile stress in the incident direction. As the wavelength and rising time increased, there was a tendency for the amplitude of stress concentration to initially rise and then converge. Moreover, a series of 3D FEM models were established to evaluate the effect of different initial stress states on the dynamic failure of the tunnel surrounding rock. The results indicated that the failure of the surrounding rock was significantly influenced by the direction of the static maximum principal stress and the direction of the dynamic disturbance. Under the coupling of static and blasting loading, damage around the tunnel was more prone to occur in the dynamic and static stress concentration coincidence zone. Finally, the damage modes of rock tunnel under static stress and blasting disturbance from different directions were summarized and a proposed support system was presented. The results reveal the mechanisms of deep-buried rock tunnel destruction and dynamically triggered rockburst.

Aqueous zinc ion hybrid capacitors (ZIHCs) are considered one of the most promising electrochemical energy storage systems due to their high safety, environmental friendliness, low cost, and high power density. However, the low energy density and the lack of sustainable design strategies for the cathodes hinder the practical application of ZIHCs. Herein, we design the N and O co-doped porous carbon cathode by annealing metal-organic framework (ZIF-8). ZIF-8 retains the original dodecahedral structure with a high specific surface (2814.67 m²/g) and I _G/I _D ratio of 1.0 during carbonization and achieves self-doping of N and O heteroatoms. Abundant defect sites are introduced into the porous carbon to provide additional active sites for ion adsorption after the activation of carbonized ZIF-8 by KOH treatment. The ZIHCs assembled with modified ZIF-8 as the cathode and commercial zinc foil as the anode show an energy density of 125 W · h/kg and a power density of 79 W/kg. In addition, this ZIHCs device achieves capacity retention of 77.8% after 9000 electrochemical cycles, which is attributed to the diverse pore structure and plentiful defect sites of ZIF-8-800(KOH). The proposed strategy may be useful in developing high-performance metal-ion hybrid capacitors for large-scale energy storage.

Roof disaster has always been an important factor restricting coal mine safety production. Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics, which is an effective way to control the hard limestone roof. In this study, the effects of various factors on the reaction characteristics and mechanical properties of limestone were analyzed. The results show that the acid with stronger hydrogen production capacity after ionization (pK _a<0) has more prominent damage to the mineral grains of limestone. When pK _a increases from −8.00 to 15.70, uniaxial compressive strength and elastic modulus of limestone increase by 117.22% and 75.98%. The influence of acid concentration is manifested in the dissolution behavior of mineral crystals, the crystal defects caused by large-scale acid action will lead to the deterioration of limestone strength, and the strength after 15% concentration reformation can be reduced by 59.42%. The effect of acidification time on limestone has stages and is the most obvious in the initial metathesis reaction stage (within 60 min). The key to the strength damage of acidified limestone is the participation of hydrogen ions in the reaction system. Based on the analytic hierarchy process method, the influence weights of acid type, acid concentration and acidification time on strength are 24.30%, 59.54% and 16.16%, respectively. The research results provide theoretical support for the acidification control of hard limestone roofs in coal mines.