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Amino acids modified hydroxyapatite (AA/HAP) composites were synthesized in the presence of different concentrations of serine (Ser), aspartic acid (Asp) and glutamic acid (Glu). The composites were characterized by Fourier transform infrared spectrometer, X-ray diffractometer (XRD) and transmission electron microscope (TEM), and were evaluated in the in vitro remineralization of acid-etched bovine enamel. The results show that amino acids (AA)can interfere with the growth of HAP crystal plane, resulting in the increase of the solubility and decrease of the ordered structure of the HAP crystals. XRD patterns and TEM analysis show that AA has a significant inhibitory effect on the[100] crystalline direction of HAP.Meanwhile, the HAP composites modified by AA have refined crystalline size when compared with the HAP without AA. The cytotoxicity of the materials was evaluated by CCK-8 assay and the results show that the relative cell activity of AA/HAP composites is better than the HAP. Field emission scanning electron microscope images show that the HAP without amino acids and the HAP modified with two different concentrations of amino acids both can repair the surface lesions of bovine enamel. While only the AA/HAP synthesized in the presence of 10 mmol·L-1 Ser, Asp and Glu generates a dense remineralization layer with a thickness of approximately 22 μm in the subsurface restoration, and obtains the best surface microhardness recovering.

Amino acids modified hydroxyapatite (AA/HAP) composites were synthesized in the presence of different concentrations of serine (Ser), aspartic acid (Asp) and glutamic acid (Glu). The composites were characterized by Fourier transform infrared spectrometer, X-ray diffractometer (XRD) and transmission electron microscope (TEM), and were evaluated in the in vitro remineralization of acid-etched bovine enamel. The results show that amino acids (AA)can interfere with the growth of HAP crystal plane, resulting in the increase of the solubility and decrease of the ordered structure of the HAP crystals. XRD patterns and TEM analysis show that AA has a significant inhibitory effect on the[100] crystalline direction of HAP.Meanwhile, the HAP composites modified by AA have refined crystalline size when compared with the HAP without AA. The cytotoxicity of the materials was evaluated by CCK-8 assay and the results show that the relative cell activity of AA/HAP composites is better than the HAP. Field emission scanning electron microscope images show that the HAP without amino acids and the HAP modified with two different concentrations of amino acids both can repair the surface lesions of bovine enamel. While only the AA/HAP synthesized in the presence of 10 mmol·L-1 Ser, Asp and Glu generates a dense remineralization layer with a thickness of approximately 22 μm in the subsurface restoration, and obtains the best surface microhardness recovering.

The catalytic flame retardant system has the characteristics of the low addition amount, high char formation efficiency, stable carbon structure at high temperature and so on. The research on flame retardant method and mechanism of the catalytic flame retardant system has become more and more important. In this paper, the status of research and development on catalytic flame-retardant polymer systems at home and abroad was reviewed. The applications research progress on metal oxides, carbon materials, metal salts, montmorillonite, molecular sieves and boron phosphors in catalytic flame-retardant polymer systems was introduced. The catalytic mechanism in the char-forming process of condensed phase was discussed. At last, it was pointed out that the development trend of catalytic flame retardant polymer materials is to develop new carbon materials represented by graphene and to achieve superfine and organic of catalytic flame retardant.

This article presents an experiment and simulation study on the effect of Z-pin reinforced on the pull-off and sheat carrying capacity of fiber placement composite T-joints,we used CMT5504 to conduct the pull-off test meanwhile we used MTS to conduct the shear test. we studied Z-pin reinforced And non-reinforced test-pieces,drawing Load-displacement curves.The pull-off test results donate that Z-pin can effectively improved the pull-off carrying capacity of T-joints and slow the decrease of the load significantly after pick loading compared to the non-reinforced T-joints. The failure location is between stiffener and interlayer. The shear test results donate that Z-pin can effectively improve the shear carrying capacity of T-joints. The failure location of Z-pin reinforced test is between skin and interlayer and the failure location of non-reinforced test is bwtween stiffener and interlayer. On this basis,we created pull-off and shear model of T-joint specimens. The interface failure was simulated with cohesive zone model,and the effect of Z-pin was simulated with nonlinear springs inserted into the interface. The numerical results agree well with the test data and shows that the model is effective.

At present， most smart wearable devices are smart watches， wristbands， etc.， which have the problems of high rigidity， poor comfort and frequent charging， making it difficult to meet the requirements of ergonomics and clothing comfort. They cannot be worn for a long time to achieve all-weather monitoring. Textile triboelectric nanogenerator （T-TENG） can be integrated into shoes and clothing as flexible power sources and self-powered sensors， making it an ideal wearable device for active human health monitoring and enforcement. However， most of the reported T-TENG need to be packaged and then integrated into clothing before use， resulting in a reduced air permeability of clothing. In addition， most of the current studies are in the laboratory stage， and the properties of T-TENG such as durability， sensitivity and stability in actual use are not fully considered. In this paper， the basic working mode， material selection， manufacturing method， integrated footwear and clothing mode， and application scenarios of T-TENG were reviewed. The preparation methods of T-TENG for nanofiber membrane and textile composite materials， fiber/yarn-based T-TENG， and fabric-based T-TENG were mainly discussed. New strategies for the development and integration of comfortable T-TENG in the future were proposed， including the large-scale preparation of T-TENG， the integration of T-TENG and traditional clothing， the compatibility of T-TENG monitoring accuracy and comfort， and the durability and stability of T-TENG.

Nano-TiCp/GH3536 composite powders were prepared by mechanical alloying （MA） and thermal plasma spheroidization （TPS） methods. The flowability， bulk density， particle size distribution， sphericity， and microstructure of the composite powders before and after MA-TPS treatment were studied by Hall flow meter，Scott volumeter， XRD， particle size analyzer， scanning electron microscope， and transmission electron microscope. The results show that the preformed powders obtained by MA-5 h treatment are irregular shape powders with non-uniform adhesion of nano-TiC particles on the surface of the GH3536 substrate. Compared with the original GH3536 powders， the number of equiaxed grains in the preformed powders increases and the crystal grains are refined， but the flowability and bulk density decrease.The nano-TiCp/GH3536 composite powders obtained by the second TPS treatment are spherical， and the original irregular nano-TiC particles are spheroidized and uniformly distributed inside the GH3536 substrate. After removing the submicron particles with an average particle size of 183.27 nm， the flowability， bulk density， and sphericity of TPS composite powders are further improved.The TEM images of submicron particles show that the nanoscale GH3536 microspheres are uniformly coated with a layer of TiC， the structure is similar to the core-shell， and spherical TiC particles are found in the powder. The average spherical degree， average particle size， flowability， and bulk density of the nano-TiCp/GH3536 composite powders prepared by the two-step method are 0.965，33.65 μm，17.1 s/50 g，and 4.184 g/cm3， respectively.

Metal oxides are often used as electrode materials for supercapacitors because of their high capacity， low cost， suitability for commercialization， and environmental friendliness. In this study， Mn-MOF was used as a precursor and placed in ethanol for ion exchange and etching reaction with Co（NO3）2， followed by heat treatment in air， and finally highly crystalline CoMn2O4 two-dimensional nanorod structures were obtained on a carbon cloth（CC） substrate. SEM and XRD analyses of CoMn2O4/CC prepared with different Co（NO3）2 additions and Mn2O3/CC obtained by direct heat treatment were performed， and electrochemical properties were measured by cyclic voltammetry test， constant current charge/discharge test and AC impedance test. The results show that the parent structure of CoMn2O4/CC is relatively well preserved after 0.3 g Co（NO3）2 etching， forming a nano-hollow structure， and the vertical nanorod structures grow in situ on carbon cloth after heat treatment wrapping carbon fibers uniformly and densely， ensuring high mechanical stability and electrical conductivity due to the absence of any binder addition. The electrode material has an area specific capacitance of 809.8 mF·cm-2 at the current density of 1.2 mA·cm-2 and the capacitance retention is 79.1% after 5000 cycles at the current density of 5 mA·cm-2，showing potential application prospects.

10Cr13Co13Mo5Ni3W1VE (S280) martensitic ultra-high-strength stainless steel under aging at 200, 400, and 500 ℃ was used as the research object. Through XRD, TEM, EBSD and other test methods, combined with electrochemical test methods and X-ray photoelectron spectroscopy (XPS) tests, the microstructure evolution of S280 and the structural composition and corrosion resistance of the passivation film were analyzed. The relationship between the stability characteristics of the passivation film and the microstructure of the material was studied.The results show that S280 steel aged at 500 ℃ has fine and dispersed precipitates with rich Cr and Mo elements distributed in martensite laths. As the aging temperature increases, there is no obvious precipitation of retained austenite and reverse transformed austenite.At the potential (0.1-0.85 V) of forming a passivation film, the S280 passivation film is a p-type semiconductor in a pH=8.5 borate buffer solution, having a double-layer film structure.The outer layer is composed of loose and porous Fe/Cr hydroxide, and the inner layer is composed of dense Cr/Fe oxide whose composition is mainly Cr2O3.The electrochemical impedance test combined with Mott-Schottky analysis proves that S280 steel aged at 200 ℃ has the best corrosion resistance. Its corrosion resistance is affected by the grain boundary characteristics and the element segregation caused by the precipitated phase.

The closed-cycle process will generate a large number of radioactive aerosols, and its high humidity, high acidity, and high radioactivity lead to rapid failure and high replacement frequency of glass fiber high-efficiency filters. In order to solve the above problems, hydrophobic modification of the traditional glass fiber filter material was proposed to improve its tolerance to severe conditions. The low surface energy modifier (polydimethylsiloxane) was used to realize the chemical hydrophobicity of filter material. The microstructure was constructed by introducing SiO2 nanoparticles to further improve hydrophobicity. The modification effect was analyzed by means of SEM, FTIR and contact angle measuring instrument, and the filtration performance of the modified filter material was further studied. The research results show that the modification can effectively improve the hydrophobicity of the glass fiber filter material and improve its moisture resistance. The static contact angle of the simply chemically modified filter material can reach 146°, and the modified filter material after the introduction of SiO2 nanoparticles exhibit an angle of more than 150°. When the mass fraction of polydimethylsiloxane and SiO2 nanoparticles is 2.0% and 0.5%, respectively, the corresponding filter material GF-PS-0.5 shows the best acid resistance, which is mainly due to the synergy of chemical hydrophobicity and microstructural hydrophobicity. The hydrophobicity of GF-PS-0.5 remains stable after a sufficient amount of γ-irradiation, indicating its good radiation resistance. The modified filter material maintains excellent filtration performance, and the filtration efficiency exceeds 99.99%. The modification process can improve the tolerance of the glass fiber filter material without influencing the filtration performance, showing a good application prospect.

In order to study the corrosion resistance of three different superhydrophobic coatings (MZS-1, MZS-2 and ZnO@ZIF-8) on AZ91D magnesium alloy surface in 5% (mass fraction) NaCl solution. The microstructure, wettability and corrosion resistance of the superhydrophobic composite coating were tested and characterized by field emission scanning electron microscope, static contact angle tester, electrochemical workstation and salt spray tester, respectively. The results show that the corrosion of the superhydrophobic coatings does not occur until 192 h after salt spray treatment among the three types of superhydrophobic coatings, and the corrosion of the MZS-1 superhydrophobic coating is the most serious. The surface pitting of the MZS-2 superhydrophobic coating doesn't occur until 240 h later, and the contact angle is still high after salt spray treatment, so the corrosion resistance of the MZS-2 composite coating is the best.The polarization curve tests indicate that the corrosion current density of three superhydrophobic coatings are still one order of magnitude lower than that of the metal matrix after salt spray treatment for 240 h, showing excellent corrosion resistance. The superhydrophobic coating can effectively increase the corrosion resistance of metal materials.It can effectively prevent the infiltration of corrosive ions and provide long-term protection for the matrix because of its water repellency.

The MCrAlY(M=Ni, Co or NiCo)has become a widely used bond-coat material of thermal barrier coatings (TBCs) due to its advantages of high-temperature oxidation resistance and high thermal expansion coefficient, with the continuous increase in turbine inlet temperature of aero engines and gas turbines. However, the stress distribution at the interface between the bond and top coating in thermal barrier coatings becomes more complicated under a high-temperature service environment. The failure of the bond-coat leads to the spalling of the top coating, which limits the development of the thermal protection coating field. The development process of the bond-coat was briefly described.The failure behavior of the bond-coat interface due to high-temperature phase transition, increased thermal and growth stresses, and S-element diffusion was focused on, and the failure mechanism of the bond-coat interface was analyzed. The research on improving the bond-coat interface failure at home and abroad was summarized. The synergistic strengthening of MCrAlY by rare earth and nanoparticles is proposed, which provides a research direction for the future optimization design of thermal bond-coat systems.

The variation rule of deformation structure and magnetic properties of high strength non-oriented electrical steel with cold rolling were studied by field emission scanning electron microscopy(SEM+EBSD), rapid temperature tube furnace and AC magnetic properties measuring instrument. The results show that the rough strips with a large number of substructures and smooth strips with a small amount of deformation are formed in cold-rolled high strength non-oriented electrical steel. The rough strip has a γ orientation, mainly {111}〈110〉, and the smooth strip has a {112}〈110〉 and {001}〈110〉 orientation. In the rough strips, there are a lot of shear bands with width of about 2-3 μm, which show an angle of 20°-35°to the rolling direction. And the quantity increases gradually with the increase of the reduction rate. There is a certain misorientation between the shear band and the matrix. With the increase of the reduction rate, the shear band gradually changes from {111}〈110〉 to {223}〈110〉, and the misorientation between the shear band and the matrix gradually increases. After annealing, the texture of Goss and {111} increases, while the texture of {001} decreases. The rolling direction magnetic induction intensity increases, the transverse magnetic induction intensity decreases, the magnetic anisotropy is significant, and the iron loss decreases.

The foaming agent alkyl polyglucoside was added into graphene oxide dispersion to generate graphene oxide microbubble agglomerates, which were then combined with polyurethane sponge skeleton through impregnating, the as-obtained composite sponge was rapidly frozen in liquid nitrogen and reduced by hydrazine vapor to form the reduced graphene oxide/polyurethane composite sponge with special three-dimensional hierarchical porous structure as well as superhydrophobicity and flexible piezoresistive sensing performance. The results show that the reduced graphene oxide/polyurethane composite sponge-based flexible stress-strain sensor has a sensitivity of up to 3.8(gauge factor, GF), a response time as low as 45 ms. In addition, reduced graphene oxide/polyurethane composite sponge has good superhydrophobicity with water contact angle(WCA) up to 152.5°, which has potential application in the complex environment such as wet and underwater.

A γ′ phase strengthened NiCoCrFeAlTiMoW alloy was prepared in a vacuum arc melting furnace, and X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile testing machine were used to investigate the coarsening behavior and the evolution law and mechanism of mechanical properties of the γ′ phase after 200 h long-term aging at 750, 850 ℃ and 950 ℃.The results show that γ′ phase remains spherical during the aging process when the aging time is extended, γ′ phase size gradually increases and the solidification phenomenon occurs at 750, 850 ℃ and 950 ℃. The alloy has a high diffusion activation energy with a value of 357 kJ/mol.This is mainly due to the fact that the matrix is a high entropy solid solution with complex composition, and the diffusion of Al and Ti atoms in the matrix becomes difficult due to the hysteresis diffusion effect. The yield strength of the alloy gradually increases after aging at 750 ℃, the yield strength after aging at 850 ℃ first increases and then decreases, and gradually decreases after aging at 950 ℃. The change in the yield strength of the alloy is caused by the increase in the size of the γ′ phase, which leads to a shift in the precipitation strengthening mechanism of the alloy.

In order to solve the protection problem of metal parts surface, the mixed metal coating was prepared on 45# steel by cold spraying, and then synthesized into FeCrAlCu, FeCrAlCuNi, FeCrAlCuCo, FeCrAlCuNiCo HEA coating by induction remelting technology.The effect of the addition of Ni and Co on the phase composition, microstructure, hardness and wear resistance of the FeCrAlCu series HEA coating were investigated by XRD, SEM, EDS, TEM, microhardness tester and abrasive wear tester, etc. The results show that the coating of FeCrAlCu series HEA is composed of FCC+BCC phase, and the addition of Ni element can promote the formation of FCC phase, and the addition of Co element can promote the formation of B2 phase(AlCo).The microstructure of FeCrAlCu HEA coating is dendrite. With the addition of Ni and Co, the dendrite number in the coating increases and coarsenes obviously. When Ni and Co are added at the same time, the friction property of FeCrAlCuNiCo HEA coating is the best. The hardness of the coating is 565.5HV, the friction coefficient is 0.349, and the wear rate is 3.97×10-5 mm3·N-1·m-1.

The glass fiber fabric reinforced polytetrafluoroethylene (GF/PTFE) self-lubricating composite was investigated by using a high frequency and high load oscillating friction and wear tester MYB-500 to carry on a whole life wear test. The self-lubricating performance and damage characteristics were studied, and the wear debris and wear surface were analyzed by microscopic detection method to discuss the key factors affecting the self-lubricating stability and service life of material. Results show that the life cycle of GF/PTFE self-lubricating composite exhibits an obvious stage characteristics, and can be divided into three stages, including running-in, stable stage and failure stage based on the change of friction coefficient and wear depth. Real-time monitoring of friction coefficient and friction temperature can effectively reflect the self-lubricating performance and life stage of the material. The change of wear depth and wear surface analysis show that the wear exhibits notable non-uniformity. According to wear mechanism, the inhomogeneity of the initial thickness of the material has a significant influence on the inconsistency of the damage during the wear process as well as its life. Therefore, by improving the curing process, the stable stage in life cycle can be prolonged and the service life of the material can also be increased.

The time-temperature-transformation (TTT) diagrams of 7A36 aluminum alloy extruded plate were determined by an interrupted-quench method. The quenching precipitation behavior was investigated by calculate phase diagram(CALPHAD) combined with optical microscopy(OM), scanning electron microscopy(SEM), transmission electron microscopy(TEM), scanning transmission electron microscopy(STEM) and high-resolution transmission electron microscopy(HRTEM). The results show that the critical quenching rate for inhibiting the phase transition of 7A36 aluminum alloy by 0.5% is about 15.7 ℃/s. Based on 10%TTT diagram, the nose temperature is determined to be about 338 ℃ with the transformation time of about 22 s. The precipitation of η(MgZn2), T(Al2Zn3Mg3), S(Al2CuMg) or Cu-Zn rich Y phases can be found depending on different isothermal holding temperatures and time, and the precipitation behavior is described in the TTT curve, which is described as a time-temperature-precipitation diagram.η equilibrium phase tends to occur at grain boundary(GB) first and then at sub-grain boundary(SGB) and on dispersoids in the interior of grains, at higher isothermal holding temperature, the size of η phase is larger. The electrical conductivity increases first and then decreases with the increase of holding temperature; isothermal holding at 420 ℃, the increase of electrical conductivity is caused by precipitation of η phase and T phase, while at 330 ℃ and 240 ℃, the increase of electrical conductivity is due to the precipitation of η phase, T phase, S phase and Y phase.

In view of the heat dissipation of electronic components with high heat flux, five phase change heat transfer cold plates with different structures and processing methods were designed, the effects of cold plate structural parameters, heat flux, refrigerant flow rate, and heat source layout on heat transfer performance, resistance of cold plate, and the pump power consumption were experimentally studied. The results show that the designed perforated cold plate has excellent heat transfer performance. The designed perforated cold plate maintains a temperature difference of less than 25 ℃ between the heat source surface and the refrigerant inside the cold plate when dissipating a total heat output of 5 000 W and a heat flux of 38 W/cm2, with cold plate resistance less than 30 kPa and pump power consumption less than 35 W. The processing method of cold plate has a significant influence on its heat transfer effect. The cold plate should adopt integrated design as far as possible to reduce the link of heat transfer and avoid the contact thermal resistance caused by the chimerism of different materials. When multiple heat sources have different heat flux densities, placing the higher heat flux heat source closer to the inlet of the cold plate achieves better heat transfer efficiency.

Scanning electron microscopy, transmission electron microscopy and energy disperse spectrum were used to analyze the morphologies, microstructures and compositions of Hf-rich inclusions in DZ125 and DZ22 Ni-based superalloys. The solidification microstructures of Ni-based alloys with different Hf additions were investigated by simulation experiments, and the formation mechanism of Hf inclusions was clarified. The results indicate that there are irregular inclusions on the edges of DZ125 and DZ22 alloys. The white inclusions are HfO2 phase, and the accompanying gray inclusions mainly comprise Al2O3. The Hf has a strong tendency to accumulate in the alloy, and large size Hf-rich phase of above 100 μm can form in the alloy when the Hf content is high. With the decrease of Hf content, the Hf-rich phases become smaller and distributed more evenly. At high temperature, Hf has a high strong driving force of spontaneous reaction with oxygen in the alloy melt and ceramic shell/core oxides, leading to the formation of HfO2 inclusions on the casting surface. When the dispersion of Hf is insufficient, Hf tends to segregate at the interface of oxide ceramic phases and melt, reacting with Al2O3 in the ceramic and SiO2 in the silica sol binder at high temperature, resulting in the formation of HfO2 inclusions on the casting surface.

Considering the important effect of mineral composition, this article deduces the similarity criterion based on the dimensional method. Similar materials suitable for tuffs with different degrees of weathering in karst areas are made. By virtue of the orthogonal experiment, the mechanical behaviors of the similar materials with various mix proportions are systematically investigated. It provides an important reference and basis for the next proposed model tests on the stability of tuff strata in karst areas. The results indicate that a stable mechanical behavior can be achieved for the similar material made of quartz sand, cement, gypsum, limestone powder, diatomite, red clay, and water. Moreover, it is also found that the aggregate and the binder have an observable influence on the mechanical behavior of the similar material. With an increase in the amount of cement and gypsum, the homogeneity of the sample increases, failure mode in which the specimen shows lateral compression damage. However, with increasing the amount of quartz sand, there is a tendency that a weak structural plane will be generated within the sample. Thus, this similar material can be satisfactorily used for simulating limestone of different weathering degrees in a scaled model test.

Tea waste biochar/graphitic carbon nitride (TBC/g-C3N4) composites were prepared by high temperature thermal polymerization with tea waste as raw material and melamine as precursor. The morphology, structure and photoelectric characteristics of the photocatalysts were characterized by SEM, XRD, XPS, UV-Vis DRS, PL and EIS.The performance of TBC/g-C3N4 composites for photocatalytic reduction of U(Ⅵ) under visible light irradiation was studied, and the mechanism of photocatalytic reduction of U(Ⅵ) by TBC/g-C3N4 composites was discussed.The results show that when the mass fraction of TBC is 5%, the initial pH value is 4 and the amount of catalyst is 1 g/L, the removal rate of U(Ⅵ) by TBC/g-C3N4 composites is 99.64% after visible light irradiation for 30 min, which is much higher than that of g-C3N4 (58.8%).The removal rate of U(Ⅵ) is above 80% after five cycles, which indicates that TBC/g-C3N4 composites has an excellent photocatalytic stability.The addition of TBC makes the band gap of g-C3N4 reduced from 2.63 eV to 2.14 eV, widens the visible light absorption range, promotes the separation of photogenerated charge, reduces the recombination rate of photogenerated electron-hole pair, and thus enhances the photocatalytic activity of TBC/g-C3N4composites.This study provides a new idea to design and synthesizethe photocatalysts with efficient, low-cost and environmentally-friendly.

The application of magnesium alloy is limited due to its poor deformation ability and corrosion resistance.In order to extend its application，a novel Mg-0.12Ca-0.08Ba alloy was designed and prepared by low alloying method.The corrosion behavior of the as-prepared alloy in 3.5%NaCl solution was investigated by immersion test in NaCl solution，SEM，EDS analysis and electrochemical test.Results showed that with the increase of corrosion time，the surface of extruded and extruded annealed Mg-0.12Ca-0.08Ba alloy changed from local pitting to large-scale corrosion，and the corrosion products gradually increased.The corrosion products were mainly MgO and Mg(OH)2，the line roughness and surface roughness of the alloy surface increased significantly，and the hydrogen evolution rate decreased gradually.Compared with extruded magnesium alloy，the hydrogen evolution rate of annealed alloy was slower，the open circuit potential was higher，and the corrosion current was smaller，indicating that the corrosion resistance performance of annealed alloy was better.

Friction capacity is a principal characteristic in designing driven piles. Considering the complexities in analyzing the behavior of piles, many studies have recommended the use of machine learning for this purpose. However, the used methodologies need to be updated and improved with respect to recent computational advances such as the development of optimization algorithms. In this work, three metaheuristic algorithms, namely equilibrium optimizer (EO), biogeography-based optimization (BBO), and salp swarm algorithm (SSA) are deployed to optimize an artificial neural network (ANN) for predicting pile friction capacity based on pile geometry, effective stress, and shear strength. The findings indicate the suitability of the proposed algorithms. More specifically, in the training phase, the ANN supervised by SSA yielded the most accurate results, whereas in the testing phase, the BBO-ANN outperformed the two other models. The calculated mean absolute error, Pearson correlation coefficient, and root mean square error for the models are as follows: 6.0740, 0.9385, and 7.0678 for the EO-ANN, 6.1450, 0.9440, and 6.7343 for the BBO-ANN, and 5.9684, 0.9395, and 7.1322 for the SSA-ANN. It is shown that both SSA-ANN and BBO-ANN can serve as efficient tools for the reliable design of driven piles, providing efficient computational intelligence alternatives to traditional design methods.

This paper designed 7 groups of C40 crack resistant concrete mix and conducted experimental research on working properties, mechanical properties, deformation properties and crack resistance, with monolithic laminated wallboard technology. The test results find that: the shrinkage compensated concrete with curing agent in light sand shows that the curing agent in light sand gives full play to the synergistic expansion effect. While significantly improving the design strength of concrete, it effectively controls the crack generation in the solidification process of concrete specimens, which has good crack resistance and durability. From the aspect of concrete mix design, this study provides an effective solution to control the cracks of cast-in-place concrete structures in the process of application of assembled monolithic laminated wallboard technology.

A 3D model is established to simulate the bond performance of corroded RC beams, in which the non-uniform corrosion of tensile reinforcement and confinement conditions (characterized by the thickness-diameter ratios of 1.9–3.8 and stirrup confinement index of 0–8.3%) are investigated. In the 3D numerical model, fine modeling was adopted to consider the influences of corrosion on the steel-concrete interface and the non-uniform corrosion was considered by separating the tensile bars into two parts with inconsistent diameter loss. Meanwhile, a two-stage numerical analysis method was utilized, to reflect the corrosion-induced concrete cracking by applying forced displacement and subsequently analyzed their flexural bond performance. In comparison to the existing experiments, the proposed 3D numerical model is proved to be reasonable. In addition, the simulation results show that the increment of the (residual) bond strength generated by the increasing thickness-diameter ratio increases with the mass loss rate, while the increases of stirrup confinement index cause much more increases in the (residual) bond strength for the corroded RC beams than the un-corroded beams. Furthermore, a bond stress-slip relationship is proposed taking the non-uniform corrosion and confinement conditions into account, which correlates well with the experiments.

High-entropy alloys have attracted great attention in various fields due to their high-entropy effect, severe lattice distortion, slow diffusion and special and excellent material performance due to the combination of various alloying elements in equal or near-equal molar proportions. Its high strength and hardness, fatigue resistance, excellent corrosion resistance, radiation resistance, near-zero thermal expansion coefficient, catalytic response, thermoelectric response and photoelectric conversion make high-entropy alloys have potential applications in many aspects. High-throughput computation and machine learning technology have rapidly become powerful tools to explore the huge composition space of high-entropy alloys and comprehensively predict material properties. The basic concepts of high-throughput computing and machine learning were introduced in this paper as well as the advantages of first-principles calculation, thermodynamic/kinetic calculation and machine learning in the research of high-entropy alloys. The application research status of high-entropy alloy composition screening, phase and microstructure calculations and performance prediction were summarized. In the final part, the existing problems, and the solutions and future prospects of this field were summarized, including developing tools for first-principles calculations and machine learning of high-entropy alloys, building high-quality databases for high-entropy alloys and integrating high-throughput computing with machine learning to globally optimize the mechanical property and service performance of high-entropy alloys.

In order to explore the wear mechanism of Cr4Mo4V bearing steel under the condition of instantaneous dry friction， the silicon nitride ball and Cr4Mo4V steel disc friction pair were used to explore the influence of load changes on the friction characteristics of Cr4Mo4V bearing steel under the conditions of an ambient temperature of 300 ℃， a speed of 0.3 m/s and a sliding dry friction. Results showed that when the load increased in the range of 1.2～2.4 GPa，the friction coefficient of Cr4Mo4V bearing steel decreased from 0.89 to 0.42，while the wear rate increased from 2.05×10-6 mm3/(N·m) to 2.68×10-6 mm3/(N·m). Oxidation reaction occurred on the worn surface， and the types of oxides produced under different load conditions were different. Besides， the main wear mechanisms of Cr4Mo4V were oxidation wear and adhesion wear.

Aiming at the problem of fatigue life prediction of aluminum alloy wheel hub, a fatigue life prediction model considering damage accumulation is proposed and tested. The Finite Element Models of a wheel hub under bending fatigue test and radial fatigue test are established, and the main failure positions are studied by simulation analysis. The S-N curves of material and part are established by using the nominal stress method, and the average stress of the asymmetric cyclic load borne by the wheel hub is corrected by using the Morrow line. Considering the rotation process of the wheel hub, a theoretical model for predicting the fatigue life is constructed by using the linear cumulative damage theory. Taking an aluminum alloy wheel hub as an example, the life calculated by the theoretical model is 448.2 thousands revolutions. Compared with the fatigue life of 473.3 thousands revolutions given by the bending fatigue test, the error is about 5.6%, which verifies the effectiveness of the fatigue life prediction theoretical model.

When the rolling bearing has a local fault, it will produce a complex vibration response. From the objective reality and irregularity of the inner ring′s actual fault shape, the displacement excitation function is introduced to qualitatively analyze the gradual change of the ball position when it passes through the fault area, and a random number sequence is used to list the characteristics of the irregularity of the bottom. Considering the radial load of the bearing and the slipping phenomenon of the balls through the fault area, a bearing inner ring dynamics model of the local gradient fault is established, and the accuracy of the model is verified by comparing and analyzing the characteristic frequency values of the fault under different rotational conditions.

In order to study the fatigue crack propagation of the fuselage skin under uniform pressurized cyclic load, experiments were carried out with the self-made aircraft fuselage skin uniform pressurized fatigue device. Firstly, the stress intensity factor was calculated by the extended finite element method. Then, the deflection angle of the crack was calculated based on the maximum circumferential stress criterion and the strain energy density factor criterion, and the fatigue crack propagation path of the fuselage skin was predicted. Finally, the fatigue fracture was analyzed under scanning electron microscope. The results show that the crack propagation paths predicted by the two criteria are basically consistent with the crack propagation path obtained by experiment.The surface cracks of the fuselage skin are mixed mode cracks. With the increase of the crack length, KⅠ first increases and then decreases, KⅡ first decreases rapidly to around 0, then oscillates around 0, and finally increases rapidly when the lower hole is about to penetrate. Observing the fatigue fracture shows that the fatigue cracks are initiated by multiple fatigue sources. The crack propagation zone has typical quasi-cleavage fracture characteristics, and the fatigue crack growth rate first increases and then decreases with the increase of crack length. The instantaneous fracture zone is a typical dimple feature with different sizes.

Inconel 617 nickel-based superalloy with 3 mm wall thickness was welded by laser beam using two different heat input welding parameters. The microstructure of the welded joint was observed by optical microscope and scanning electron microscope, and the mechanical properties of the welded joint at room temperature (25℃) and high temperature (900℃) were tested. The results show that the laser welding heat input has a significant effect on the microstructure and mechanical properties of Inconel 617 welded joints. The front width of the laser weld obtained by high heat input (200 J/mm) process parameters is 3.88 mm. The grain size in the middle of the weld fusion zone is coarse, and the grain orientation is disordered. The secondary dendrite arm spacing in the middle of the weld is large (6.71 μm). The carbide particle size between the dendrites is coarse, and the solidification microsegregation of Mo, Cr alloy elements is serious. The width of heat affected zone is about 0.29 mm. The eutectic structure of γ+carbide is formed in the grain boundary and grain interior. This is because during the heating process of the welding, the spherical carbide particles and the surrounding austenite in the heat-affected zone liquefy and the eutectic structure is formed during the solidification process after welding. The front width of the laser weld obtained by low heat input (90 J/mm) process parameters is 2.28 mm, the grains inside the weld are columnar which is formed by epitaxial growth along the fusion line and directional solidification along the heat flow direction. The secondary dendrite arm spacing in the middle of the weld is small (2.26 μm), the carbide particles between dendrites are small, and the width of heat affected zone is about 0.15 mm. The tensile strength test at room temperature (25℃) shows that the welded joints obtained under high heat input fracture from the middle of the weld, and the tensile strength and elongation decrease, which is caused by the segregation of solid solution elements in the weld. The welded joints obtained under low heat input fracture from the base metal. At high temperature (900℃), all samples fracture from the base metal, which is due to the weakening of the grain boundary of the base metal at high temperatures.

As a carbon-free hydrogen-rich energy carrier, ammonia has gained increasing attention and application in the context of carbon peaking and carbon neutrality. This study evaluated the stress corrosion cracking (SCC) sensitivity of four target materials, A516-70, 16MnDR, 15MnNiDR, and Q370DR, in a liquid ammonia environment at 25 °C and 1.03 MPa by slow stress rate tests to determine their SCC sensitivity index. The microstructure, grain size, misorientation, hardness, strength, and micro-fracture morphology of these materials were compared to analyze the SCC mechanism. The results showed that 15MnNiDR exhibited significant SCC sensitivity while both 16MnDR and A516-70 demonstrated certain levels of SCC sensitivity in liquid ammonia. However, Q370DR showed no SCC sensitivity under these conditions. The misorientations observed align with the strains experienced by each respective carbon steel in liquid ammonia. An unstable passivation film formed on the surface of 15MnNiDR steel when exposed to liquid ammonia whereas Q370DR developed a stable oxide film which contributed to its weak SCC sensitivity.

In this study, a pre-matching method was developed based on measured performance parameters and theoretical calculations of turbochargers. First, the turbocharger of a natural gas engine was subjected to a comprehensive performance experiment. According to the experimental results, the maximum efficiencies of the turbine and compressor are 70% and 75%, respectively, and the efficiency of the turbine drops sharply from 70% to 56.6% as the pressure ratio increases from 1.25 to 2.4. In this thesis, a specific turbocharger pre-matching software has been developed in conjunction with a database. Three turbines and three compressors were selected from the self-developed database for matching and comparative study using this method. The simulation results showed that the maximum efficiency of turbine #1, #2 and #3 is 71.3%, 72.2% and 72.7%, respectively, and the efficiency of these three turbines is concentrated between 65% and 72.5%. Obviously, the maximum efficiency of the turbine has increased by 1.3–2.7% and the overall efficiency has improved after the pre-matching. Therefore, this developed pre-matching method can reduce time cost, improve work efficiency and engine performance, and is important for the design and development of turbochargers.

Reinforced concrete (RC) structures exposed to cryogenic temperature environment, the bond performance of rebar-concrete is related to the characteristics of concrete material and rebar. The mechanical characteristics of concrete material and rebar vary greatly at cryogenic temperatures. To illustrate the bond behavior of rebar-concrete at cryogenic temperatures, the pull-out specimens were simulated focusing on the coupling effects of cryogenic temperatures and confinements on the bond behavior. The model considers the surface characteristics of deformed reinforcement and the cryogenic temperature effects on the mechanical characteristics of materials. The confinements were applied to the specimens by carbon fiber-reinforced polymer (CFRP) and stirrup respectively, and the temperature ranges from 20 °C to − 120 °C. The effects of thickness diameter ratio (c/d), and confinements on the bond behavior at cryogenic temperatures were discussed. The results showed that at cryogenic temperatures, the failure modes are similar to those at 20 °C for the specimens with c/d ≤ 3.75. However, for the specimen with c/d = 4.0, the specimen at − 120 °C exhibits splitting failure due to the increase of brittleness. The bond strength at cryogenic temperatures is improved with the increasing c/d. The effects of confinements on the failure modes are small, but the bond strength is improved by the CFRP confinements and stirrup confinements. According to the numerical data, the developed bond strength model and bond stress-slip model considering the effects of confinements could provide better predictions of the bond behavior at cryogenic temperatures.

In order to study the effects of different sintering temperatures and heat treatment on the microstructure and properties of copper alloys, TiH2/Ti-doped Cu-Y2O3 composite powders were prepared by high-energy ball milling in this paper. After pressing-sintering-heat treatment, copper matrix composites were obtained. The microstructure of the composite was characterized by optical microscope (OM) and scanning electron microscope (SEM), and Vickers hardness tester was used to test its hardness and eddy current conductivity tester. The results show that after high-energy ball milling and mixed powder, elements Y, Ti and O are evenly distributed on the surface of the composite powder. The sintering temperature and heat treatment has an important influence on the microstructure and properties of TiH2/Ti-doped Y2O3 reinforced copper-based composites. The TiH2/Ti-doped Y2O3 reinforced copper matrix composites achieved the excellent properties after sintering at 850 ℃ for 2 h and aging at 450 ℃ for 3 h. The electrical conductivity and hardness of TiH2-doped Y2O3 reinforced copper-based composites are 86.9% IACS and 70.1 HV respectively, and the electrical conductivity and hardness of Ti-doped Y2O3 reinforced copper-based composites are 76.8% IACS and 73.6 HV.

As a new type of energy storage device, aqueous zinc-ion capacitors (AZICs) have excellent performance, such as high power density, high energy density, long cycle life and high safety.AZICs have a high application prospect in the field of civil electronic equipment and military electrified weapons and equipment, and are expected to become a new generation of energy storage scheme instead of lithium-ion batteries.In this paper, the recent advances of carbon-based materials for zinc ion capacitors, such as activated carbon, carbon nanotubes, graphene and biomass derived carbon were summarized. The zinc ion storage performance of MXenes was analyzed in detail, and the energy storage mechanisms of transition metal oxides were revealed. It is pointed out that developing the cathode materials with high capacity, high voltage tolerance and low temperature adaptability is of great importance.

To improve the mechanical properties and corrosion resistance of the hydraulic column in the mine, a semiconductor fiber-coupled laser was used to laser-clad iron-based alloy powder on a 27SiMn steel substrate (SUB). The microstructure, mechanical properties, and corrosion resistance of the obtained cladding layer (CL) were studied based on experiments. Results show that equiaxed grains at the top of the CL are fine and tightly arranged. Compared with the SUB, the CL average microhardness is increased by 0.3 times, the average friction coefficient is decreased by 0.12, and the wear amount is significantly reduced. The bonding strength between the CL and the SUB is good, and the tensile strength is increased by 10.82%. Compared with the SUB, the mechanical properties and corrosion resistance of the CL are better. The research has an important guiding significance for the practice of hydraulic column repair and strengthening engineering.

The carbon fiber (T300-6K) with a three-dimensional four-way braiding structure was selected as the reinforcement, and the 3D-Cf/6061Al composites at different braiding angles (10°, 20° and 30°) were prepared by the pressure infiltration method, and the effects of different braiding angles on the mechanical properties of the composites were discussed. It is found that the pressure infiltration avoids the weak bonding force between the carbon fiber and the aluminum matrix to a certain extent, so that a better infiltration effect can be obtained. The bending performance of the composites become worse with the increase of braiding angle. With the increase of braiding angle, the strain force of the composites also increases, and the greater the elongation is, the better the toughness is. When the braiding angle was larger, the transverse component force of the fiber was larger, the unevenness of the fiber fracture surface increases, the pulling phenomenon was obvious.

In order to investigate the interface stability of α-Fe/V4C3, the interface structure of three different atomic stacking sequences (Fe-on-C, Fe-on-V and Bridge) of (100)α-Fe/(100)V4C3 were optimized by using the first-principles calculations with pseudo potential plane wave method. The structural stability of α-Fe/V4C3 was measured by the work done of separation for the three configurations. The calculated interfacial separation work of the three configurations is 4.29, 1.43 eV and 2.70 eV, respectively, which larger interfacial separation work indicating stronger interface stability.Therefore, V4C3 precipitated in α-Fe mainly exists in the Fe-on-C configuration, and its interface stability is the strongest. The electronic structure properties of α-Fe/V4C3 were studied by calculating the density of states, differential charge density and electron localization function. The results show that in the Fe-on-C structure configurations, there is a charge-depleted zone for Fe atoms at the interface, and the lost charge transfer to the interface. Due to the strong electronegativity of C atoms, strong mixed ions/covalent bonds are formed at the interface, and the bond and interaction between Fe and C atoms are significantly stronger than that between Fe atoms and V atoms. Meanwhile, according to the total density of states and projected density of states, it is found that the Fe-d orbital and the C-p orbital hybridize in the -4.5 eV to -2.5 eV region, promoting the formation of the Fe—C covalent bond.

The friction and wear of mechanical parts mainly occurs on the surface of the material, and about 80% of the failures of parts are caused by surface wear.Friction and wear increase the loss of material and energy, and reduce the reliability and safety.Using laser cladding technology to prepare a high entropy alloy coating on the surface of the substrate can achieve a good metallurgical combination between the coating and the substrate, so as to achieve the purpose of improving surface wear resistance.The main factors affecting the wear resistance of the high entropy alloy coating are the mechanical and physical properties of the coating material (such as hardness, plasticity and toughness), defects generated during the cladding process (such as surface roughness, pores and cracks), friction conditions (such as high temperature environment and corrosive environment).In this paper, the influencing factors and strengthening mechanism of laser cladding high entropy alloy coatings were reviewed and summarized.First of all, the influence of laser process parameters (such as laser power, laser scanning speed, spot diameter) and post-treatment processes (such as heat treatment and rolling) on the quality and performance of the coating were explained.Secondly, the influence of component element selection, high temperature environment and corrosive environment on the wear resistance of the coating was described.Finally, the problems existing in the preparation of high entropy alloy coatings by laser cladding technology were analyzed, and the future development trends were forecasted, such as developing new materials based on far-equilibrium material design theory, using electric field-magnetic field synergy or laser-ultrasonic vibration composite technology to improve the wear resistance of coatings, etc.

Dry UMCA(Ultrasonic Mechanical Coating and Armouring)is a deposition coating technology that only needs to be carried out under normal temperature and pressure, and its principle is similar to mechanical alloying.Although the UMCA process is still in the preliminary exploration stage in the world, it has shown great potential in coating preparation due to its unique advantages.The experiment method of UMCA was introduced and the influence laws of process parameters on coating quality was summarized.It was found that the influence laws of different material combinations had both similarities and differences.And the reasons for the difference were mainly analyzed from the perspective of energy.Besides, the possible formation mechanism of the coating was analyzed in a broad sense.Finally, the problems to be solved urgently and the development direction of UMCA process were put forward.

The composite nanocontainer of corrosion inhibitor (MSN-QB) was prepared by loading octahydroxyquinoline (8-HQ) and benzotriazole (BTA) on mesoporous silica nanoparticles(MSN) simultaneously using vacuum adsorption and layer-by-layer self-assembly technology, and added to the epoxy coating to obtain a new coating (MQB). SEM, TEM, FT-IR, Zeta-potential and TGA were used to study the structure changes of the nanocontainer before and after loading corrosion inhibitors and the stimulus response release behavior of the corrosion inhibitors, and electrochemical test and salt spray test were used to study the improvement of coating protection performance by layer-by-layer self-assembly technique. The results show that the loadings of 8-HQ and BTA in MSN-QB are 6.8%(mass fraction) and 7.1%, respectively. MSN-QB has pH response characteristics. The release of 8-HQ and BTA are both inhibited under neutral conditions, but can be released under alkaline (pH=10) and acidic (pH=4) conditions. The release rate under alkaline conditions is higher. MQB coating has the best corrosion resistance. After immersed in 3.5%NaCl solution 20 d, the MQB coating has the largest|Z|0.01 Hz value(2.0×109 Ω·cm2), more than twice that of MQ+MB coating.

The surface topography of parts serves as a crucial role for machining quality. In order to achieve accurately prediction of the surface topography of precision milling, a surface topography simulation method based on wavelet packet analysis and frequency spectrum analysis of cutting vibration is proposed in this paper. In the paper, firstly, the ball-end milling is taken as the research object and the motion trace model of cutting edge changing with time based on the workpiece coordinate system is established. And then the vibration equation obtained by wavelet packet analysis and spectrum analysis is put into the model. Finally, the surface topography of the part is simulated and predicted by employing MATLAB. The comparisons between simulation and trial experiments suggest that the accuracy of the surface topography simulation prediction model based on wavelet packet analysis and frequency spectrum analysis of vibration signal offers a reference for the actual processing and production.

Based on the dynamics theory of rolling bearings, the fluid-solid-thermal three-phase coupled numerical analysis method is used to study the temperature field and strength of the cage in the ultra-low temperature environment. The influence of the temperature distribution, stress distribution and inlet flow rate of the cage on the fluid flow rate and fluid pressure is obtained. The results show that the temperature of the cage decreases with the increase of the inlet flow rate and the maximum temperature is at the circumferential position of the pocket; the cage stress increases with the increase of the inlet flow rate and the maximum stress is at the axial position of the pocket.Research can provide reference for solving bearing life extension and reliability problems in ultra-low temperature environment

Based on the three-dimensional W-M fractal function, a three-dimensional rough surface was bulidt by SOLIDWORKS, and then the three-dimensional ball-rough surface contact numerical model of torsional fretting with the energy wear law being introduced by the user subroutine UMESHMOTION was established by ABAQUS. Thus, the influence of initial surface roughness on the frictional wear process of torsional fretting was studied. Firstly, the reasonability of the rough surface model was verified by the analytical solution of dimensionless contact area in G-W model. Simultaneously, in comparison with experimental wear results, the accuracy and validity of the numerical model for predicting torsional fretting wear was proved. The research results show that the change of surface roughness has a significant effect on torsional fretting wear. To be specific, wear volume, friction dissipation energy, and wear rate all increase with the increase of surface roughness, which indicates that initial surface roughness can aggravate surface wear. And friction activation energy decreases with the increase of surface roughness. It is clear that the rougher the surface, the lower the threshold for wear activation. Therefore, reducing initial surface roughness can effectively alleviate the torsional fretting wear.

Requirements for the cockpit of military vehicles are constantly increasing as a result of escalating threats. The traditional transparent bulletproof armor based on glass have been unsatisfactory to relevant application requirements, and lighter and thinner transparent armor based on ceramics is becoming main option. Similar to other bulletproof armor, the main research fields of transparent bulletproof armor include:seek materials with higher performance for armor components; guide the structure design and ballistic test by experiment or computer simulation; understand the main performance of armor materials, the holistic performance of the armor system and the interaction between the components of the whole system more deeply. Based on this notion, the advantages and disadvantages, preparation technology, development, and application situation of the three kinds of ceramic materials commonly used in transparent armor were summarized. Among the three kinds of ceramics, sapphire has the best static parameters. As for the actual effect of bulletproof, the polycrystalline ceramics are better. The main reason for this phenomenon is that the different fragmentation modes of the two kinds of ceramics lead to the difference of projectile-target interaction effect. After that, the crack growth under high strain rate and bullet-proof property of single crystal, polycrystalline ceramics and glass were discussed. Under uniaxial, high strain rate compression, the crack propagation characteristics of materials are sensitive to impact energy/velocity. Polycrystalline ceramics has a composite failure mode of intergranular fracture and intragranular fracture. Under high energy impact, the damage zone of sapphire is similar to polycrystalline ceramics. Lower than critical energy, some sapphire plate orientations damage would be dominated. Finally, the material selection standards and structural design principles of each functional layer were summarized and prospected. Fine grain polycrystalline ceramic materials with high Young's modulus and high hardness are preferred for the strike-layer. Materials with good fracture toughness, high bending stiffness and the ability to localization of the damage within a narrow region should be selected for the intermediate layer. The materials of backing layer require ductility and low density. The bulletproof efficiency of the transparent-armor systems depends on the type and the degree of interaction/integration of different functional layers.

Owing to the excellent biocompatibility and corrosion resistance of titanium and its alloys in the biological environments, they are one of the best materials in the medical implant applications. Moreover, it has a lower elastic modulus (comparable to bone) than traditional metal implant materials which is an influential property due to the stress-shielding effect. There are some requirements for implant materials according to their clinical use and the periphery tissues. Hence, some factors should be considered, such as metal degradation, toxicity issues, surface characteristics, biocompatibility, and fusion with bone. Considering the above-mentioned information, titanium material design with superior performance to meet the essential clinical needs is an important challenge and attracts much attention from the academicians in the biomaterial field. This paper discusses the structural and performance characteristics of medical titanium alloys and the current research status in the direction of orthopedic applications. Furthermore, in future research, through changing the elemental composition, increasing the surface modification, and optimizing the production process, titanium alloy materials could have the excellent comprehensive performance to serve human beings better.

The surface damage resistance of chemically strengthened aluminosilicate glass is very important. The surface hardness and modulus are closely related to the damage resistance of glass. The micromechanical behaviors such as surface hardness and modulus of chemically strengthened aluminosilicate glass were analyzed by finite element method, and compared with the results of nanoindentation experiment. The results show that the load displacement curve of nanoindentation calculated by finite element method is in good agreement with the experimental results. According to the load displacement curve obtained by finite element simulation, Oliver and Pharr method was used to calculate the hardness and Young’s modulus. The calculated results are very close to the experimental values. The relationship between the yield strength of aluminosilicate glass and the stress-strain in the plastic region calculated by Larsson’s plastic formula is used in the simulation process. The simulation results are in good agreement with the experimental results, which indicates that the accuracy of the plastic parameters of aluminosilicate glass obtained by Larsson’s plastic formula is high. Finally, according to the stress distribution obtained by finite element simulation, the elastic-plastic deformation behavior of aluminosilicate glass before and after chemical strengthening was analyzed. The results show that the surface compressive stress layer produced by chemical strengthening has more influence on the elastic zone of aluminosilicate glass, but has less influence on the plastic zone.

Inspired by increasing demand of advanced pulsed power capacitors, the development of lead-free dielectric ceramic capacitors with high energy storage density and temperature-insensitive performance are extremely crucial. Herein, the lead-free relaxor ferroelectric ceramics based on (1-x) (Na0.5Bi0.5)0.6Sr0.4TiO3- xSr0.7La0.2ZrO3 [abbreviated as (1-x)NBST-xSLZ] are prepared by the solid-state reaction route. The large recoverable energy density (Wrec) of 3.45 J/cm3 and efficiency (η) of 90.1% are simultaneously realized in 0.86NBST-0.14SLZ ceramic due to increased breakdown strength. Furthermore, both the Wrec and η of 0.86NBST-0.14SLZ ceramic display superior of thermal stability (20–180 °C), frequency stability (1–1000 Hz), and cycle stability (104) within a satisfactory range of variation. In addition, the 0.86NBST-0.14SLZ ceramic can also achieve a large current density (CD) of 625 A/cm2, an ultrahigh power density (PD) of 50 MW/cm3 and a fast discharge rate (τ0.90) of 160.8 ns at 160 kV/cm. These results demonstrate that the 0.86NBST-0.14SLZ ceramic could be a highly competitive and eco-friendly relaxor ferroelectric material for next-generation pulsed power capacitors.

Supercapacitors have become a new type of energy storage device widely used due to their high efficiency, fast speed and good cycle stability, and electrode material is a key issue restricting their development. The porous niobium nitride fibers were prepared by electrospinning combined with reduction nitride technology using pentachloride as raw material, and Nb4N5||Nb4N5 symmetrical button capacitance was prepared. In order to improve the electrochemical performance of electrode material, NaHCO3 was added into Na2SO4 electrolyte. The results show that the prepared niobium nitride fiber exhibits a tetragonal phase, continuous and porous on the surface. The porous niobium nitride electrode has two mechanisms of electric double layer and pseudocapacitive energy storage. The specific capacitance of the capacitor increases to 187 F·g-1 with the NaHCO3 addition of 15 mmol·dm-3. The buffering effect inhibits the dissolution of niobium nitride, effectively reduces the solution resistance, the solution impedance R1 and the diffusion impedance WR reduce to 1.22 Ω and 1.47 Ω respectively and the ionic conductivity improves. The carrier concentration increases to 6.58×1024 cm3, and the relaxation time of the capacitor is shortened to 0.24 s at the same time.