Enhancing Li2S deposition and oxidation kinetics in lithium-sulfur batteries, especially the potential-limiting step under lean electrolyte, can be effectively achieved by developing conductive catalysts. In this study, by using ZnMoO4 as precursors, Zn-doped molybdenum carbide microflowers (Zn-Mo2C) composed of speared porous sheets are fabricated with a hierarchically ordered structure. Density functional theory calculations indicate that Zn doping shifts the d-band center on Mo atoms in Mo2C upward, promotes the elevation of certain antibonding orbitals in Mo─S bonds above the Fermi level, enhances d-p interaction between lithium polysulfides (LiPSs) and catalysts, weakens both S─S and Li─S bonds of LiPSs. Incorporating Zn significantly reduces the Gibbs free energy barrier for the rate-limiting step of the Li2S2 → Li2S conversion, from 0.52 eV for Mo2C to just 0.05 eV for Zn-doped Mo2C. Thus, the synthesized Zn-Mo2C demonstrates impressive bifunctional electrocatalytic performance, significantly advancing sulfur reduction and Li2S decomposition. Moreover, this modification enhances charge transfer within the Zn-Mo2C/LiPSs system, synergistically accelerating the kinetics of Li2S4 to Li2S reduction and Li2S oxidation. The Zn-Mo2C/S cathode demonstrates impressive electrochemical performance, achieves remarkable cycling stability with a minimal capacity decay of 0.021% per cycle over 1000 cycles at 5 C, underscoring its potential for high-energy applications.

The designed SPI can change the interface impedance and enhance the combustion performance of the propellant by regulating the current density.

Lightweight, highly integrated and miniaturized modern high-power electronic devices put forward higher requirements on the heat removal efficiency of heat sinks. Herein, the bidirectional carbon hierarchical structure consisting of high crystalline carbon (HCC) layer and carbon nanotubes (CNTs) reinforced aluminum foam (AF) composites were prepared by the combination process of dopamine annealing and plasma enhanced in-situ growth. The hybrid carbon reinforcements establish two high-speed thermal conduction paths on the surface of the aluminum skeleton, enhancing the skeleton axial transport efficiency. The calculation results of non-equilibrium molecular dynamics (NEMD) reveal that the utilization of an optimal thickness of HCC layers can effectively strengthen the axial thermal conduction flux of the skeletons while minimizing the detrimental impact on radial heat flow from aluminum substrate to CNTs caused by thermal resistance. The composites exhibit the effective thermal conductivity of 43.17 ​W ​m−1 ​K−1, which is 5.6 times higher than that of the pristine AF. The instantaneous cooling rate of 16.1 ​K ​s−1 and the cooling efficiency of 34.6 ​% demonstrate the superior heat dissipation performance of the composites compared to other similar carbon phase reinforcing heat sinks. Therefore, the composites prepared in this work holds promising potential for heat removal applications.

The demand for lightweight heat dissipation design in highly miniaturized and portable electronic devices with high thermal density is becoming increasingly urgent. Herein, highly thermal conductive carbon nanotubes (CNTs) reinforced aluminum foam composites were prepared by catalyst chemical bath and subsequent in-situ growth approach. The dense CNTs show the intertwined structure features and construct high-speed channels near the surface of the skeletons for efficient thermal conduction, promoting the transport efficiency of heat flow. The regulation of the process leads to a proportion increase in the (1 1 0) crystal plane of the aluminum substrate. The calculation results of non-equilibrium molecular dynamics (NEMD) demonstrate that (1 1 0) crystal plane is conducive to enhancing thermal boundary conductance thus the desirable equivalent thermal conductivity is obtained in the model system. Moreover, the phonon behaviors at the heterointerface observed in phonon density of states spectrums (PDOS) show that the interface system with (1 1 0) crystal plane possesses the superior coupling effect suggesting the brilliant transmission capacity. The theoretical results of NEMD and PDOS provide a microscopic explanation for the high thermal conductivity observed in the prepared composites with a high content of Al (1 1 0) crystal plane. The composites exhibit a thermal conductivity of 30.63 W center dot m-1 center dot K-1, improved by-300 % as compared to unmodified aluminum foam. The cooling efficiency of 28.63 % obtained in the composites indicates outstanding heat dissipative performance among other similar works. The composites prepared in the work could hold bright prospects for the thermal management field.

In practical applications, C/C composites often need to be joined to metals. However, one major issue that needs to be addressed is the high residual stress in heterogeneous joints. To enhance the interfacial bonding between C/ C composites and metals, this study has utilized ultrafast high -temperature shock (UHS) to selectively oxide C/C composites, resulting in the formation of a zig-zag microstructure on the surface. By achieving an extremely short processing time of only 30 s, the efficiency of oxidation process has been improved by several hundred times, leading to a reduction in the rate of weight loss to less than 3%. After brazing, the filler penetration zone is formed, which effectively increases the bonding area between filler and C/C composites, improves pinning effect and alleviates residual stress. Notably, the joints demonstrate a shear strength of 25.3 MPa, which is 1.9 times higher compared to the original joints without employing oxidation process.

A novel surface modification and joining method utilizing ultrafast high-temperature shock (UHS) has been investigated to achieve interfacial bonding between C/C composites and TC4 alloy by using Joule heating effect. The process involves surface selective oxidation of the C/C composites and subsequent ultrafast joining, both achieved within short time periods of 30 s and 20 s, respectively. Surface selective oxidation created annular gaps on the C/C composite surface which increased the contact area between the filler alloy and the base material, while suppressing the propagation of cracks. Joule heating of the C/C composites induced a non-equilibrium temperature field, which melted the filler alloy and facilitated interfacial joining through heat conduction. Notably, the temperature of TC4 metal (CTE -9.5 x 10-6 K-1) was significantly lower than that of the C/C composites (CTE -1.5 x 10-6 K-1), thus suppressing the expansion of TC4 near the heterointerface due to the self-limiting effect exerted by the cold end. As a result, the thermal expansion matching was improved and the residual stress in C/C-TC4 heterostructure was relieved. The shear strength of optimal joints reached 31.7 MPa, representing a 2.4 times increase compared to the conventional joining method.

The practical application of Li-S batteries encounters hurdles in maintaining cycling durability and rate capability under realistic conditions. Electrostatic self-assembly stands as a captivating avenue for exploring new frontiers in nanoscale catalysis. Leveraging renewable bio-oil both as a carbon source and self-polymerization precursor, ultrafine Mo2C nanocrystals anchored on bio-oil-derived 3D hierarchical carbon matrix (Mo2C@-BOC) are fabricated by a facile NaCl template-assisted electrostatic self-assembly and followed annealing procedure. Densely anchored ultrafine Mo2C nanocrystals, intertwined with highly conductive carbon nanosheets, unveil an enhanced exposure of catalytically active sites for lithium polysulfide immobilization, conversion, and supply amply nucleation sites to mediate the fast precipitation of Li2S2/Li2S. Attributed to these favorable features, Li-S cells based on the as-designed catalytic host attain satisfactory cyclability with a minimum capacity fading rate of 0.0144 % over 1000 cycles and excellent rate capability. Decent performance can be achieved even at a high sulfur loading of 8.0 mg cm-2 and a low electrolyte-to-sulfur ratio of 3.5 mu L mg-1. This strategy for solving the shuttle effect under high sulfur loading provides a promising solution for the further development of high-performance Li-S batteries. This work provides a rational strategy for solving the shuttle effect under high sulfur loading and sheds light on the great potential of Mo2C@BOC for developing more practical Li-S batteries.

The realm of high-performance supercapacitor electrodes grapples with the inherent limitations of biomass-derived carbons: an inadequate count of ion adsorption locales and sluggish ion mobility. Attaining scalability in the synthesis of hierarchical porous carbon (HPC) with precisely defined pore architectures remains an enduring challenge. This review showcases the successful synthesis of HPC from bio-oil on a large scale, accomplished through a MgO template-assisted self-assembly polymerization, followed by sequential pyrolysis and KOH activation strategies. The optimized carbon (HPC1.5-4) achieves a potent specific surface area of 2069 m(2) g(-1 )and a pore volume of 1.30 cm(3) g(-1) with hierarchical micro-, meso-, and macropores, thus providing ample ion adsorption sites and ion diffusion pathways. Three-electrode supercapacitor fabricated by HPC1.5-4 presents a high specific capacitance of 296 F g(-1) at 1 A g(-1), outstanding rate capability, and satisfactory cyclic durability. Furthermore, the symmetric supercapacitor in the Na2SO4 electrolyte harvests a high energy density of 18.9 Wh kg(-1) at 469.4 W kg(-1).

Thermal interface materials are crucial for addressing the hot issues of a rapid increase in thermal density in narrow and limited service spaces. Flexible and designable epoxy resin (EP) based composites are competitive choice yet lacks desirable thermal conductivity (-0.2 W m-1 K-1) and mechanical properties (tensile strength: -19.6 MPa). Herein, EP-based composites with a reinforced three-dimensional (3D) interconnected carbon material architecture were prepared by in-situ growing 1D carbon nanotubes (CNTs) on the surface of 2D carbon fiber braid (CFB) and infiltrating matrix EP. CNTs not only promote the wettability between carbon fibers inside CFB and EP but also observably bridge the adjacent carbon fibers. The analysis of numerical models reveals the prominent contribution of 3D CFB/CNTs network to a significant increase in thermal conductivity. Nonequilibrium molecular dynamics (NEMD) indicates the high intrinsic thermal conductivity of CNTs in both systems: single CNT model and CNT/Ni model. The coupling behavior of high-frequency phonons at the interface contributes to the in-plane thermal transport. The in-plane thermal conductivity of 7.86 W m-1 K-1 and the through-plane thermal conductivity of 5.85 W m-1 K-1 are obtained in the composites with 23.2 wt% hybrid fillers, increased by 3830 % compared to neat EP. The tensile (58.93 MPa) and compressive strength (138.83 MPa) are also enhanced, meeting practical demands. These properties even perform no obvious changes after 100 cycles of bending. The stable and reliable EP-based composites with outstanding comprehensive performance designed by this work have enormous application potential in the advanced heat dissipation system.

Efficient multi-path heat dissipation is urged to be designed for balancing the heat density generated in highly integrated electronic devices. Herein, aluminum foam/carbon composites were fabricated by chemical bath and annealing method to realize the effect of strengthening the effective thermal conductivity while retaining the convective heat transfer characteristics of the porous structure. The results show that the continuous and high crystalline carbon coating can be obtained in the optimized composites prepared with 350 g dopamine addition at 600 degrees C annealing temperature. When compared with amorphous carbon, the phonons in crystalline carbon can carry more energy during the heat transport in terms of high phonons density of states, and their scattering behavior can be alleviated. A smaller temperature gradient is further established in the system. Hence, a desirable thermal conductivity, 21.44 W m- 1 K-1, is obtained in the optimized composites, which is almost 3 times that of pristine aluminum foam (7.67 W m- 1 K-1). Additionally, the remarkable cooling efficiency of 24.71% in comparison to other studies, suggests that aluminum foam/carbon composites hold great potential as thermal management materials in addressing the issue of intense heat generation.

Ceramics are difficult to machine into complex shapes due to their high hardness and brittleness. In practical applications, ceramics often need to be jointed to themselves or metals. Traditional joining processes such as brazing and diffusion bonding are inefficient and costly, greatly limiting their practical applications. To solve the problems, current work explores the characteristics, applications, and prospects of unconventional and efficient joining techniques of ceramics. The joining processes are classified by heat sources, including resistance brazing, flash joining, laser welding/brazing, arc welding, and microwave joining. Additionally, current work provides solutions for resistance brazing of non-conductive ceramics, microwave joining of low dielectric loss ceramics, and laser welding of transparent ceramics. Among these techniques, USP laser welding is one of the most promising rapid joining techniques due to its ability to effectively reduce heat affected zone and residual stress.

Surface structure of C/C composites has been regulated through electrochemical corrosion at room temperature to modify the residual stress and improve the joining strength when brazed to Nb. The unique crevice corrosion in C/C composites is investigated to reveal the change of corrosion depth and fiber size. The interlacing zone of carbon fiber reinforced brazing alloy replaces the reaction layer in the original joint. Joining area is increased dramatically and the continuous crack will be hindered. The interlacing zone eliminates the stress concentration and relieves the residual stress through reducing the property mismatch. All advantages contribute to the joining quality of C/CNb. Shear strength of C/CNb joint with 80 μm depth reached 37.7 MPa, which was 1.2 times higher than that of original joint. Surface structure design of C/C composites not only expands the application in structure component, but also exhibits the promising application in energy field.

The brush surface structure of SiCf/SiC has been designed to obtain the robust SiCf/SiC-alloy joint by reducing the residual stress and improving interface bonding. SiC fibers are exposed through thermal corrosion at a low temperature, forming the transition layer of SiC fiber-reinforced AgCuTi. The transition layer replaces the original plate reaction layer, which increases the joining area effectively and forms the 3D network of the reaction layer. The crack propagation is hindered, and SiC fibers increase the interfacial bonding. The residual stress is reduced by decreasing the property mismatch between SiCf/SiC and alloy with this transition layer. All these improvements contribute to the high shear strength. The shear strength of joints reached 41.4 MPa with the transition layer of 67 mu m, twice higher than that of original joints of 20.7 MPa.

We studied the long-term corrosion behavior of carbide/316L stainless steel joints brazed with AgCuX alloys (X = Ti, In). The results show that the Cu-based solid solution (Cu (s,s)) in the brazing alloy is the weak link of corrosion germination. Ti increases the Fermi level and decreases the *H adsorption energy (delta G(*H)) of Cu(s,s), thus leading to a higher thermodynamic tendency of hydrogen evolution. In contrast, In decreases the Fermi level and the d band center of Cu (s, s) leading to a positive delta G(*H), which improves the corrosion resistance. The results agree with the mechanical performance tests.

In this study, alumina added silica glass was fabricated by rapid sintering synthesis. The alumina added samples consist of amorphous matrix phase and dispersed mixed phases including mullite and cristobalite. Dispersed strengthening phases do not induce cracks, instead, improve the overall mechanical properties. At the same time, alumina added sample maintains a similar good corrosion resistance compared with pure silica glass sample. This work provides a modification method to enhance the mechanical property of silica glass without damaging its corrosion resistance.

提出了一种能够引导末端执行器以期望速度跟踪目标的轨迹规划方法.该方法可以实现避障并满足关节限制要求.基于轨迹规划方法,设计了一种利用自由飘浮空间机器人跟踪与捕获章动自旋卫星的自适应控制策略.此外,该控制策略还考虑了最优能耗、测量误差和优化误差.首先,为了使执行器的跟踪误差和机械臂的能耗最小,将空间机器人的控制策略描述为一个关于关节速度、力矩和避障距离的不等式约束优化问题.然后,推导出一个系数为下三角矩阵的显式状态方程,并对目标函数进行解耦和线性化.设计了一种关节速度和力矩分段优化方法去代替传统的凸二次规划方法求解最优问题,这种方法具有较高的计算效率.最后,利用李雅普诺夫稳定性理论验证了所提控制方法的收敛性.

C/C composites are brazed to GH3536 superalloy with BNi2+Ni interlayer based on in-situ alloying conception. Through the liquid-solid reaction and diffusion, the original microstructure of C/C/Cr23C6/Ni(s,s)+Cr3Ni2+Ni-Si + Cr9Mo21Ni20/GH3536 is transformed into C/C/Cr7C3/Ni(s,s)/GH3536. High Ni (s,s) content increases the deformability and uniforms the composition of joint. Residual stress caused by the property mismatch is modified through deformability increase. Both increases the joining strength consequently. The phase of low melting point diffuses into Ni interlayer, which improves the high temperature performance efficiently. The optimal range of Ni interlayer is from 150 μm to 300 μm. The highest shear strength of joint reaches 32.6 MPa and 20.1 MPa at room temperature and 1000 °C, respectively.

Co-based coating has been fabricated on Ti-6Al-4V (TC4) titanium alloy by laser cladding. The phase composition and microstructure of the coating were analyzed using metallurgical microscope (MM), scanning electron microscope (SEM), x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM), respectively. The microhardness, high temperature wear resistance and corrosion resistance of the coating were investigated by performance tests. The results show that the coating was mainly composed of CoTi, CoTi2 and Co0.5Cr1.5Ti crystalline phases and an amorphous phase. The microhardness of the coating was twice that of the titanium alloy substrate. The value of friction and wear coefficient of the coating was lower and more stable, and the wear mass loss decreased by 52% as compared with the substrate in the high-temperature friction and wear test. The oxidative wear mechanism in the condition of high temperature friction and wear was studied. Moreover, the coating exhibited better corrosion resistance than the substrate in both NaCl and H2SO4 electrolyte solutions.