The bowl-like C@FeS₂@NC (nitrogen doped carbon layer) composites were prepared via a multi-step process, namely the silicon dioxide microspheres were firstly coated with phenolic resin and then converted into carbon shell at high temperature, soon after which were subjected to solvothermal reaction, dopamine coating, high temperature vulcanization and sodium hydroxide etching. This composite material has an open three-dimensional bowl-like structure, which can well release the stress caused by volume change. Its large specific surface area (70.67 m²·g^-1) has a lot of active sites. The double carbon shell composite consisted of an inner and an outer carbon shells, as a stable mechanical framework, can enhance the electrical conductivity, while the outer NC has a good protective effect. When this composite material is used as the negative electrode of lithium-ion battery, the discharge specific capacity and charge specific capacity of the first turn are 954.3 mAh·g^-1 and 847.2 mAh·g^-1, respectively at the current density of 0.2 A·g^-1, and the corresponding Coulomb efficiency of the first turn is 88.78%. After 100 cycles, the discharge specific capacity is stable at 793.8 mAh·g^-1.

Firstly, hexagonal crystalline CdS multilayer flower-like microspheres were synthesized by hydrothermal reaction, next on the surface of which ZnO nanorods were grown on to form uniform ZnO/CdS composite, and thirdly ZnO/CdS/Ag ternary semiconductor photocatalyst was prepared by depositing Ag nanoparticles onto ZnO nanorods by photoreduction method. The prepared ZnO/CdS/Ag photocatalyst was characterized by scanning electron microscope and transmission electron microscope, while its photoelectric property, active group capture characteristics, photocatalytic degradability for methylene blue (MB) and antibacterial property were also examined. The results show that ZnO nanorods uniformly grow on the surface of CdS microspheres, and Ag nanoparticles were deposited on the surface of ZnO nanorods. ZnO/CdS/Ag ternary photocatalyst has good visible light response, low impedance and high photocurrent density. ZnO/CdS/Ag composite photocatalyst can simultaneously produce hydroxyl and superoxide radicals and other reactive oxygen groups. The degradation rate of methylene blue (MB) on ZnO/CdS/Ag ternary photocatalyst in 30 min is higher than 90%. The sterilization rate of 0.25 mg/mL ZnO/CdS/Ag to Gram-negative bacteria (Escherichia coli) is higher than 96%, and gram-positive bacteria (Staphylococcus aureus) can be completely destroyed.

The in-plane tensile strength of six carbon fiber reinforced resin-based composites with different needle punching processes decreases with the increase of needle punching density and needle punching depth. The fiber fracture at the needle punching regions can make the defects instability propagation in the material, which can induce the tensile failure of material. Based on the in-plane tensile test results and fiber cumulative damage theory, a theoretical model for analyzing in-plane tensile strength of needle punched composites are established by introducing fiber volume reduction coefficient. The prediction results of this model are consistent with the experimental results. It is found that the number of broken fiber clusters is related to the volume reduction coefficient. The model can be used to predict the in-plane tensile strength of composites with different needling processes, and to guide the design of the needle punching preforms.

Ni-based superalloys with high W content are widely used to fabricate gas turbine blades because of their high temperature mechanical properties and lower cost. The γ΄-phase is the most important strengthening phase in Ni-based superalloys, which affects the deformation behavior during tensile process. Although the influence of γ΄-phase has been studied extensively, there are few investigations on the deformation mechanism of K416B superalloy with different morphologies of γ΄-phase. Hence, the effect of γ΄-phase morphology on the mechanical behavior of K416B superalloy was assessed in the present work. The average size of γ΄-phase scattered in the as-cast alloy was about 200 nm, which could impede the mobility of dislocations in the matrix so that the yield strength increased. After heat treatment, two sizes of γ΄-phase precipitated from the matrix, the size of them were 1 μm and 100 nm respectively. During room temperature tensile deformation of the alloy after being subjected to heat treatment, dislocations could fully share the primary γ΄-phase particles, and even detour the secondary γ΄-phase particles per Orowan mechanism, therewith the yield strength of the alloy decreased. The life of as-cast K416B is longer than that of the heat-treatment counterpart. It can be interpreted that the secondary γ΄-phase particles coarsened rapidly during the durable test. Additionally, the precipitation of nano W₆C particles along the γ-γ΄ interface depleted tungsten in the alloy, which reduced the mismatch between γ and γ΄ phases, resulting in the damage of the durable life of K416B alloy.

Firstly, mullite powders were Ni-P plated by electroless plating, and next, subjected to a heat treatment at 850℃. Then coatings of blank- and Ni-P plated-mullite powders were plasma sprayed on 304 stainless steel, respectively. The friction and wear properties of the coatings at 800℃ were tested by a tribometer. The Ni-P plated powders and the plasma spraying coatings were characterized by means of SEM, XRD and Vickers microhardness tester. The results show that the optimized process parameters for electroless plating were as follows: the bath with pH 5.5 composed of NiSO₄·6H₂O 20 g/L, NaH₂PO₂·H₂O 30 g/L, Na₃C₆H₅O₇·2H₂O 20 g/L and NH₄Cl 20 g/L, the plating was conducted at 80℃for 1 h. The plated Ni-P layer on the surface of mullite powder was uniform and compact, and the heat treatment made the layer change from amorphous to crystalline consisted of Ni and Ni₃P. The sprayed mullite coating was mainly composed of mullite phase and γ-Al₂O₃ phase, and the sprayed coating of Ni-P plated powders was mainly composed of Ni, AlNi₃, Ni₃P and mullite. The introduction of Ni-P plating for mullite powders could enhance the hardness of the sprayed coating from 417.5 HV_0.2 to 500.1 HV_0.2. The sprayed coating of Ni-P mullite powders presented a good wear resistance superior to that of the blank ones. Correspondingly, the Ni-P plated powder coating has significantly lower friction coefficient with a wear rate of 13×10^-4mm³/(N·m), which was only 0.59 times of that for the mullite coating. After wear test, obvious ploughs and local spallations could be observed on the surface of mullite coating, while the surface of the Ni-P plated powder coating was smooth with less spallation. Besides, the wear forms of the two coatings were mainly plastic deformation and abrasive wear.

The precipitation behavior of second phase in non-oriented silicon steel during normalization treatment at 900~1000℃ was investigated by means of scanning electron microscope (SEM) observation and energy dispersive spectrometer (EDS), and thermodynamic and kinetic calculations. The result show that the second phases in non-oriented silicon steel are mainly AlN with a small amount of MnS. The critical nucleation radius (d*) of AlN and MnS particles increases with the increase of precipitation temperature for different matrix phases, namely α-phase, γ-phase and (α+γ) two-phase respectively, which accord with three different precipitation nucleation mechanisms i.e. uniform nucleation, grain boundary nucleation and dislocation nucleation. By taking the second phase nucleation behavior at the same temperature as comparison, among others the critical nucleation work of grain boundary nucleation of AlN is the smallest, the relative nucleation rate is the largest, so grain boundary nucleation is easy to occur in (α+γ) two-phase area. Besides, the critical nucleation radius of MnS on the dislocation line is the smallest, the relative nucleation rate is large, and the initial precipitation temperature is low, therefore, the dislocation nucleation is dominated for MnS precipitates in the α-phase matrix.

To evaluate the fatigue properties of carburized Cr-Ni gear steel, very high cycle fatigue tests were carried out at room temperature by stress ratios of 0 and 0.3. The fatigue failure modes of carburized Cr-Ni gear steel can be differentiated into interior fatigue failure with fine granular area (FGA) and surface fatigue failure with surface smooth area (SSA). According to the observation results of sites of inclusions and fatigue fracture morphology of the tested steels, therewith the interior very high cycle fatigue failure mechanism is clarified. Based on the cumulative damage method and the dislocation energy method, two kinds of interior fatigue strength prediction models for carburized Cr-Ni gear steels were established by taking the formation mechanism of fine granular area and the evaluated maximum size of inclusions into consideration. Based on the relationships between the relative size of FGA and the stress intensity factor of inclusion and stress ratio, the two fatigue strength prediction models were further modified, and the l_FGA-S-N curves for the maximum size of inclusions was given. The results show that the fatigue strength prediction model based on the cumulative damage method and the dislocation energy method can be used to evaluate the interior fatigue strength of carburized Cr-Ni gear steel by various stress ratios, however the prediction accuracy of the model based on the dislocation energy method is higher.

The phase transformation and mechanical properties of two steels of ZG04Cr13Ni4Mo with 12% Cr and 13% Cr, which being subjected to 893 K one-stage tempering and 893 K + 863 K two-stage tempering respectively, were investigated by means of thermal dilatometer, XRD and tensile tester, in order to clarify the effect of Mo and Cr, the two key alloying elements in ZG04Cr13Ni4Mo martensitic stainless steel, a candidate material used widely for hydraulic turbine runners. The results show that with the increase in Mo and Cr content, the A_s temperature (the beginning temperature of austenitization) decreases gradually. For steels with different Mo contents, the amount of martensite converted into reversed austenite in the heating and isothermally holding stage may definitely different with that by directly cooling down to ambient temperature after tempering, when they are subjected to primary tempering at 893 K within the intercritical temperature zone. Therefore, due to such difference in microstructure evolution, when Mo content increases from ~0.3% to ~0.6%, the yield strength of ZG04Cr13Ni4Mo steel containing 12% Cr decreases slightly, while the ultimate tensile strength increases slightly; in the contrast, the yield strength and tensile strength of ZG04Cr13Ni4Mo steel containing 13% Cr all slightly increased after 893K tempering with the same change in Mo content.

The effect of the anneal temperature on the microstructure, micro-texture and mechanical properties of the hot rolled Ti-6Al-4V alloy were investigated. The results show that the as rolled Ti-6Al-4V alloy presents a bimodal microstructure. The content of equiaxed α-phase increased after annealing. The content of secondary α-phase tented to decrease, whilst to be gradually spheroidized. The microstructure transformed into equiaxed structure after annealing at 900℃. With the increase of anneal temperature, the preferred orientation of α-phase were changed. Correspondingly, the micro-texture changed from B-type to mixed texture, then to B-type again. The crystal directions dispersed when the sample anneal at 800℃. The texture consisted of {0001}<3\overline{\mathrm{1}}\overline{\mathrm{2}}0>, {0001}<9\overline{\mathrm{8}}\overline{\mathrm{1}}0>, {0001}<3\overline{\mathrm{1}}\overline{\mathrm{2}}0> and {0001}<1\overline{\mathrm{2}}10>. The relationship between the mechanical performance and the annealing temperature were assessed via tensile tests. It follows that with the increased of annealing temperature, the tensile strength increased but the yield strength decreased, spontaneously, the ratio of yield strength to tensile strength decreased. In a word, the comprehensive mechanical properties of the alloy may be enhanced through proper annealing process.