Developing classes of Ag@C composites stand out for their one of a kind structure and novel physicochemical properties in later a long time. This review explores the current state-of-the-art progress in the preparation methods and the novel properties of Ag@C composites. We provide a definition of the stability of Ag@C composites, and propose strategies to improve the stability. Based on the later inquire, a summary and outlook toward the synthesis and applications of Ag@C composites are presented, aiming to accelerate the exploration of Ag@C composites and further stimulate the applications in various fields.

(CrFeCoNi) high-entropy alloy (HEA) was reinforced with various contents of WC particles from 5 wt% to 20 wt%, and prepared by powder metallurgy. The mixed powders were compacted under 700 MPa and then sintered at 1200 ° C in a vacuum furnace for 90 min. Density, phase composition, and microstructure of sintered samples were investigated. Hardness, compressive strength, wear resistance and coefficient of thermal expansion (CTE) were estimated. The results revealed the improvement of the density with the addition of WC. XRD results revealed the formation of new FCC chromium carbide phases. Scanning electron microscopy (SEM) results show a good distribution of the carbide phases over the alloy matrix. The CTE was decreased gradually by increasing the WC content. Compressive strength was improved by WC addition. A mathematical model was established to predict the behavior of the strength of the HEA samples. The hardness of the investigated HEAs was increased gradually with the increasing of WC content about 20.35%. Also, the wear rate of HEA without WC is 1.70×10⁻⁴ mm³/(N·m), which is approximately 4.5 times the wear rate of 20 wt% WC HEA (3.81×10⁻⁵ mm³/(N·m)), which means that wear resistance was significantly improved with the increase of WC content.

In this paper, the indirect thermal tensile experiments of 7075 aluminum alloy including the pre-deformation process at room temperature and the final heat tensile process were carried out, the plastic deformation behavior and forming limit of the material in the compound forming process were investigated considering three pre-deformation amounts 4%, 9%, 14%, two strain rates 0.001 s⁻¹, 0.01 s⁻¹ and four forming temperatures 300 °C, 350 °C, 400 °C, 450 °C. In the indirect hot forming process, the material is sensitive to the pre-deformation, strain rate, and forming temperature, when the strain rate is 0.01 s⁻¹, the pre-deformation amount is 4%, and the forming temperature is 400 °C, respectively, the maximum tensile deformation is 50 mm. Finally, taking the process in which the forming temperature is 450 °C as an example, according to the observation of the microstructure appearance of fracture, the fracture type in the hot forming process was judged as the ductile fracture. By analyzing the microstructure of the specimen treated with the quenching and artificial aging process, the eutectic T (AlZnMgCu) phase and α(Al) matrix formed a network of non-equilibrium alpha binary eutectic.

In the present study, the effects of microstructure, grain size, and texture after thermomechanical processing on the corrosion behavior of AISI 321 austenitic stainless steel (ASS) were studied. The as-received, coarse-grained steel ((35±3) µm) was subjected to 20%, 50% and 90% thickness reduction through cold rolling at liquid nitrogen temperature, followed by annealing at 750, 950 and 1050 °C for 15 min. Recrystallization occurred after annealing at 750 °C, and with the increasing of annealing temperature to 950 °C and 1050 °C, secondary recrystallization (abnormal grain growth) and grain growth were observed. The results showed that, after 20% thickness reduction, corrosion resistance increased significantly (21.1 kΩ·cm²) compared with the as-received condition (3.9 kΩ·cm²) due to the enhancement of γ-fiber and the creation of ∑3 boundaries. In contrast, the corrosion resistance decreased with the increasing of thickness reduction to 90% during rolling, but still depicted higher corrosion resistance compared with the as-received specimen. After annealing the 90% cold rolled (CR) specimens at 750 and 950 °C, the corrosion resistance increased in comparison with the as-received sample as a result of the more uniform microstructure, appearance of Goss and brass texture components, and grain refinement. However, significant grain growth ((112±76) µm) followed by a non-uniform structure was observed after annealing at 1050 °C and resulted in the lowest corrosion resistance (1.3 kΩ·cm²).

Based on the diffusion channel, the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed (χ=0, 1.5 wt%, 3.0 wt% and 7.0 wt%). The results show that the introduction of Si makes the reaction interface change from the lingual-tooth interface of hot-dip Al to the flat interface of hot-dip Al-Si. It also reduces the thickness of the alloy layer in the coating, especially the Fe₂Al₅ layer. When the Si content is 1.5 wt% or 3.0 wt%, the diffusion channel crosses the conjugate line of the two-phase region (FeAl₃+liquid phase) into the FeAl₃ single-phase region, and then moves to the region with higher Si content. Next, the diffusion channel cuts off the conjugate line of FeAl₃ phase, τ₁/τ₉ phase, and Fe₂Al₅ phase, which promotes the form of τ₁/τ₉ phase. The formed τ₁/τ₉ phase inhibits the diffusion between Fe and Al atoms. When the Si content is 7.0 wt%, the diffusion channel passes through the two-phase region (liquid phase+τ₅) and enters the τ₅ single-phase region. The form of τ₅ single-phase region has a strong inhibitory effect on the interatomic diffusion of Fe and Al, thereby reducing the thickness of the coating, especially the Fe₂Al₅ layer.

In this paper, the combined addition of copper or iron and sulphate ions onto TiO₂ prepared by a simple sol-gel method is studied for formic acid photocatalytic conversion. A wide structural and morphological characterization of the different photocatalysts was performed by X-ray diffraction (XRD), N₂-physisorption for BET surface area measurements, scanning and transmission electronic microscopies (SEM and TEM), UV-Vis diffuse spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS), in order to correlate the physico-chemical properties of the materials to their photocatalytic efficiencies for formic acid oxidation. Results have shown important differences among the catalysts depending on the metal added. Sulphated TiO₂/Cu (1%Cu) was the best photocatalyst obtaining about 100% formic acid conversion in only 5 min. The appropriate physico-chemical features of this photocatalyst, given by the addition of combined copper and sulphate ions, explain its excellence in photocatalytic reaction.

Two kinds of bronze-graphite-MoS₂ self-lubricating materials with copper-coated MoS₂ and uncoated MoS₂ were prepared by powder metallurgy. Friction and wear experiments were carried out under 4 N and 10 N loads respectively, and the effects of copper-coated MoS₂ on the friction performances of the materials were studied. Results showed that the way of copper-coated on the surface of MoS₂ could reinforce the bonding between MoS₂ and matrix, and inhibited the formation of MoO₂. Moreover, both materials formed a MoS₂ lubricating film on the surface during the friction process. While the lubricating film formed after copper coating on MoS₂ was thicker and had uneven morphology, it was more conducive to improving the friction performance of the material. Compared with conventional materials, the wear rate of copper-coated materials was reduced by one order of magnitude, and the friction coefficient was also reduced by 22.44% and 22.53%, respectively, when sliding under 4 N and 10 N loads. It shows that copper-coated MoS₂ can improve friction properties of bronze-graphite-MoS₂ self-lubricating materials furtherly.

Since the volume variation of silicon particles during cycling, the binding spots between Cu current collector and silicon anode raised to be one of the critical binding problems. In this work, an amino-modified Cu current collector (Cu*) is fabricated to tackle this issue. The amino groups on Cu* surface increase its hydrophilicity, which is conducive to the curing process of aqueous slurry on its surface. Meanwhile, these amino groups can form abundant amide bonds with carboxyl groups from the adopted polyacrylic acid (PAA) binder. The combined action composed of the covalent bond and mechanical interlocking could reduce the contact loss inside the electrode. However, high concentration silane coupling agent treatment will weaken the surface roughness of Cu* and weaken mechanical interlocking. What is more, the insulation of silane coupling agent reduces the conductivity of Cu and increases the impedance of battery. Considering the effect of silane coupling agent comprehensively, electrochemical performance of Cu*−0.05% is best.

Acid mine drainage (AMD) has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem. However, there are few studies focusing on the formation of AMD under moderately thermophilic conditions, hence we employed X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium, and explored the role of free and attached microorganisms in the formation of AMD. The consortium mainly comprised Acidithiobacillus caldus, Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans. The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day, and the copper dissolution rate of bornite dissolution reached 91.8% on the 24th day. SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms. XRD and XPS results showed that ore residues contained jarosite, and the dissolving residue of bornite contained elemental sulfur. The dominant bacterial genus in pyrite dissolution was A. caldus, and L. ferriphilum in bornite dissolution. To sum up, microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.

In order to improve the recovery of tungsten ores containing tin minerals, anisic hydroxamic acid (p-methoxy benzohydroxanic acid, PMOB) was synthesized and introduced as novel collector in the flotation of scheelite, wolframite and cassiterite. The flotation performance and adsorption mechanism were investigated by micro/batch flotation, zeta potential measurements and density functional theory (DFT). The micro flotation results showed that the recoveries of scheelite, wolframite and cassiterite using PMOB as collector are 97.45%, 95.77% and 90.08%, respectively, and the corresponding recoveries are 91.00%, 84.30% and 84.67% for benzohydroxamic acid (BHA). The batch flotation results revealed that the collector dosage could be reduced by about 45% for PMOB compared with BHA, in the case of similar flotation indicators. Zeta potential measurements indicated that PMOB could be adsorbed on the mineral surfaces by chemisorption. Moreover, density functional theory (DFT) calculation results showed that the substituent group −OCH₃ endues PMOB stronger electron donation ability and hydrophobicity compared with benzohydroxamic acid (BHA), p-methyl benzohydroxamic acid (PMB) and p-hydroxyl benzohydroxamic acid (PHB).

Electrolytic manganese residue leachate (EMRL) contains plenty of Mn²⁺ and NH₄⁺−N, and phosphogypsum leachate (PGL) contains large amounts of PO₄³⁻−P and F⁻. Traditional methods of EMRL and PGL discharge could seriously damage the ecological environment. In this study, an innovative method for cooperative removal Mn²⁺, NH₄⁺−N, PO₄³⁻−P, F⁻ from PG and POFT was studied. The result showed that Mn²⁺, PO₄³⁻−P and F⁻ were mainly removed in forms of Mg₃Si₄O₁₀(OH)₂, Mn₃O₄, Mn₃(PO₄)₂, Mg₃(PO₄)₂, CaSO₄·2H₂O, MnF₂, MnOOH and Ca₂P₂O₇·2H₂O, when LG−MgO was used to adjust the pH value of the system to 9.5, and the volume ratio of EMRL and PGL was 1:4, as well as reaction for 1 h at 25 °c. NH₄⁺−N was mainly removed by struvite precipitate, when the molar ratio of N:Mg:P was 1:3:2.4. The concentrations of Mn²⁺, NH₄⁺−N and F⁻ were lower than the integrated wastewater discharge standard. The concentration of PO₄³⁻−P decreased from 254.20 mg/L to 3.21 mg/L. This study provided a new method for EMRL and PGL cooperative harmless treatment.

Beach titanomagnetite (TTM) provides a cheap alternative source of Fe and Ti, but this ore is difficult to process to make suitable concentrates for the blast furnace. Recently studies showed that it is feasible to separate Fe and Ti by coal-based direct reduction. In this study, beach TTM was selected as the research object, the effects of reducing agents on reducing atmosphere in coal-based direct reduction of beach TTM were analyzed, and the role of volatiles was also studied. The results showed that when bitumite and coke were used as reducing agents of TTM, the CO produced from volatiles was involved in the reduction reaction, and the generated CO₂ provided the raw material for the reaction of TTM. The reduction effect of bitumite was better than that of coke. The reason is that bitumite+TTM had a higher gas generation rate and produced a higher CO partial pressure, while coke+TTM had a lower gas generation rate and produced a lower CO partial pressure. When graphite was used as a reducing agent, there was a solid-solid reaction in the early stage in the reaction. With the continuous accumulation of CO₂, the Boudouad reaction started and accelerated. Graphite+TTM also produced a higher CO partial pressure.

Shear-sliding mode (mode II) fracture of rocks is a vital failure form in deep underground engineering. To gain deep insight into the anisotropic shear fracture behaviors of a typical shale under high normal stress conditions, a series of direct shear tests were conducted on double-notched specimens in three typical bedding orientations (i.e., the arrester, divider, short-transverse orientations) and under five normal stresses. The mode II fracture toughness (K_IIc) is found to exhibit a significant 3D anisotropy. The maximum K_IIc is obtained in the divider orientation, followed by those in the arrester and short-transverse orientations. In contrast, the 3D anisotropy in the critical mode II energy release rate (G_IIc) is not as significant as that in K_IIc, and G_IIc in the arrester orientation is quite close to that in the divider orientation. The anisotropy in the prepeak input energy accumulated during shearing is found to be exactly consistent with that in G_IIc, which has not been noted before. Furthermore, the anisotropies in the mode II fracture resistances will, unexpectedly, not be weakened by the high normal stress. Owing to the layered structures, tensile cracks are involved during the mode II fracture process, resulting in the formation of rough fracture surfaces.

Lots of field investigations have proven that layer-crack structure usually appears during the excavation process of deep rock or coal mass. To provide experimental data for studying the formation mechanism of layer-crack structure, this study researches the influence of lateral pressure on the mechanical behavior of different rock types. Four rock types have been tested and the formation mechanism of macro-fracture surface is analyzed. Results indicate that the brittleness and burst proneness of rock or coal material are stronger than that of gypsum material due to the different mineral compositions and structures. When the lateral pressure is less than 10% uniaxial strength, the peak stress and elastic modulus increase with the increase of lateral pressure; but when the lateral pressure is larger than 10% uniaxial strength, the two parameters decrease slightly or keep steady. This is because when the lateral pressure reaches a certain value, local failure will be formed during the process of applying lateral pressure. Under the condition of low lateral pressure, the failure of the specimen is dominated by the tensile mechanism; under the condition of relatively high lateral pressure, the area of the specimen close to the free surface is tensile splitting failure, and the area far from the free surface is shear failure.

Roof pre-splitting is an effective method to control the roof with potential rock burst risk. In this study, three-point bending tests were carried out by using fine sandstone specimens with different pre-cracked lengths as test objects, and digital speckle correlation method (DSCM) and acoustic emission (AE) technology were used to track the entire process of crack propagation. The effect of pre-cracks on the fracture of rock beams was evaluated, and the mechanical mechanism of the rock beam fracture process was analyzed. The rock beam pre-splitting design method was developed, and the application effect of the method was proved by the microseismic monitoring data obtained from the 10303 working face of Jining No. 2 coal mine in China. The results show that the loading time history curve of pre-cracked beams exhibits obvious residual characteristics. Compared with the intact rock beam, the tensile strength, and maximum tensile strain of 35 mm pre-cracked rock beam are decreased by 32.4% and 33.1%, respectively and the acoustic emission b value is increased by 30.2%. According to the pre-splitting design method of rock beam, the maximum and average microseismic energy of the 10303 working face after pre-splitting construction are reduced by 25.6% and 6.4%, respectively, with excellent prevention and control effect of thick roof.

In order to simultaneously measure the initiation toughness of pure mode I and mode II cracks in one specimen, a large-size double-cracked concave-convex plate (DCCP) specimen configuration was proposed. Impacting tests were implemented in the drop plate impact device. Strain gauges were employed to measure impact loads and crack initiation time. The corresponding numerical model was established by using the dynamic finite difference program AUTODYN, and the experimental-numerical method and ABAQUS code were utilized to obtain the initial fracture toughness of the crack. Using experiments and numerical research, we concluded that the DCCP specimen is suitable for measuring the initial fracture toughness of pure mode I and mode II cracks at the same time; the dynamic initiation toughness increases with the increase of loading rate and the crack initiation time decreases with increasing loading rate; the initiation toughness of mode II crack is 0.5 times that of mode I crack when subjected to the same loading rate. For the pre-crack in the vicinity of the bottom of a sample, when its length increases from 20 to 100 mm, the dynamic initiation toughness of the pure mode I crack gradually decreases, and the longer the lower crack length is, the easier the crack would initiate, but the dynamic initiation toughness of pure mode II crack varies little.

for deep tunnel projects, selecting an appropriate initial support distance is critical to improving the self-supporting capacity of surrounding rock. In this work, an intuitive method for determining the tunnel’s initial support distance was proposed. First, based on the convergence-confinement method, a three-dimensional analytical model was constructed by combining an analytical solution of a non-circular tunnel with the Tecplot software. Then, according to the integral failure criteria of rock, the failure tendency coefficients of hard surrounding rock were computed and the spatial distribution plots of that were constructed. On this basis, the tunnel’s key failure positions were identified, and the relationship between the failure tendency coefficient at key failure positions and their distances from the working face was established. Finally, the distance from the working face that corresponds to the critical failure tendency coefficient was taken as the optimal support distance. A practical project was used as an example, and a reasonable initial support distance was successfully determined by applying the developed method. Moreover, it is found that the stability of hard surrounding rock decreases rapidly within the range of 1.0D (D is the tunnel diameter) from the working face, and tends to be stable outside the range of 1.0D.

This paper presents the one-dimensional (1D) viscoelastic consolidation system of saturated clayey soil under continuous drainage boundaries. The fractional-derivative Merchant (FDM) model has been introduced into the consolidation system to simulate the viscoelasticity. Swartzendruber’s flow law is also introduced to describe the non-Darcian flow characteristics simultaneously. The generalized numerical solution of the 1D consolidation under continuous boundaries is given by the finite difference scheme. Furthermore, to illustrate the effectiveness of the numerical method, two simplified cases are compared against the current analytical and numerical results. Finally, the effects of boundary parameters and model parameters on the viscoelastic consolidation were illustrated and discussed. The results indicated that the boundary parameters have a significant influence on consolidation. The larger the values of boundary parameters, the faster the whole dissipation of the excess pore-water pressure and soils’ settlement rate. Fractional-order and viscosity parameter have little effect on consolidation, which are primarily significant in the middle and late consolidation phases. With the increase of the modulus ratio, the whole consolidation process becomes faster. Moreover, considering Swartzendruber’s flow delays the consolidation rate of the soil layer.

In the long distance transportation of slurry filled for mining filling, there exist complex variation rules of pressure and flow velocity, pipe distribution location and other influencing factors. Electrical capacitance tomography (ECT) is a technique for visualizing two-phase flow in a pipe or closed container. In this paper, a visual detection method was proposed by image reconstruction of core, laminar, bubble and annular flow based on ECT technology, which reflects distribution of slurry in deep filling pipeline and measures the degree of blockage. There is an error between the measured and the real two-phase flow distribution due to two factors, which are immature image reconstruction algorithm of ECT and difference of flow patterns leading to degrees of error. In this paper, convolutional neural networks (CNN) is used to recognize flow patterns, and then the optimal image is calculated by the improved particle swarm optimization (PSO) algorithm with weights using simulated annealing strategy, and the fitness function is improved based on the results of the shallow neural network. Finally, the reconstructed binary image is further processed to obtain the position, size and direction of the blocked pipe. The realization of this method provides technical support for pipeline detection technology.

The wide-field electromagnetic method is widely used in hydrocarbon exploration, mineral deposit detection, and geological disaster prediction. However, apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data, making geophysical inversion and interpretation challenging. The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve. To address this, a high-frequency information extraction method is proposed based on time-domain signal reconstruction, which helps to record a complete current data sequence; moreover, it helps estimate the crystal oscillator error for the transmitted signal. Considering the recorded error, a received signal was corrected using a set of reconstruction algorithms. After processing, the high-frequency component of the wide-field electromagnetic data was not upturned, while accurate high-frequency information was extracted from the signal. Therefore, the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data.

Consideration of the travel time variation for rescue vehicles is significant in the field of emergency management research. Because of uncertain factors, such as the weather or OD (origin-destination) variations caused by traffic accidents, travel time is a random variable. In emergency situations, it is particularly necessary to determine the optimal reliable route of rescue vehicles from the perspective of uncertainty. This paper first proposes an optimal reliable path finding (ORPF) model for rescue vehicles, which considers the uncertainties of travel time, and link correlations. On this basis, it investigates how to optimize rescue vehicle allocation to minimize rescue time, taking into account travel time reliability under uncertain conditions. Because of the non-additive property of the objective function, this paper adopts a heuristic algorithm based on the K-shortest path algorithm, and inequality techniques to tackle the proposed modified integer programming model. Finally, the numerical experiments are presented to verify the accuracy and effectiveness of the proposed model and algorithm. The results show that ignoring travel time reliability may lead to an over- or under-estimation of the effective travel time of rescue vehicles on a particular path, and thereby an incorrect allocation scheme.

The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades, resulting in uneven frost heaving deformation on the subgrade surface, which in turn causes static irregularity in the slab track. Based on the hydraulics theory, a thermal-hydro-mechanical (THM) coupled model of frozen soil is established and verified. We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track System III slab tracks under uneven frost heaving deformation. The results show that, because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation, which is the key factor causing uneven frost heaving of subgrade. Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface, leading to differences in the deformation of the slab track structure: Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line, and these become consistent in north-south directions. Therefore, when selecting railway lines in seasonal frozen areas, the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades.