The effect of the microstructure of GH4742 superalloy after aging at 750℃ on the fatigue crack propagation behavior were investigated. The results show that during aging the primary block like γ′-phase grows up with a smooth boundary, the secondary petal-shaped γ′-phase breaks along the boundary, and the thrice γ′-phase re-dissolves into the matrix or coarsens into corner square like γ′-phase. The main fatigue crack easily propagates across the region without the primary γ′-phase or the secondary γ′-phase. With the increasing aging time the fatigue crack propagation rate increases. Within the near-threshold region the fatigue crack propagation rate is very sensitive to the microstructure. The smooth boundaries of the primary γ′-phase and the secondary γ′-phase lead to the increase of fatigue crack propagation rate, but the fatigue crack propagation resistance increases with the appropriate coarsening of the thrice γ′-phase within the low ΔK region. Because the range of stress intensity factor ΔK is higher in both the Paris region and the rapid propagation region, the influence of the microstructure on the fatigue crack propagation rate is decreased.

Nanocomposites of CuO/ZnO were synthesized with cetyltrimethylammonium bromide as a growth regulator by one-step hydrothermal method. The catalyst was characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectrometer (FL) and UV-Vis spectrometer (UV-Vis). The photocatalytic effect of the composite photocatalyst with different ratios of CuO to ZnO on the degradation efficiency of methyl orange under ultraviolet light irradiation, and the cyclic stability of the composite photocatalyst were investigated. The results show that CuO/ZnO photocatalysts are mainly composed of CuO nanoparticles and ZnO nanosheets. The proper amount of CuO can effectively adjust the light absorption performance of ZnO and enhance the efficiency of ultraviolet photocatalysis. Excess CuO (?7%) has inhibitory effect on ZnO ultraviolet catalytic efficiency. CuO/ZnO has good stability in the photocatalytic process.

The tension-tension fatigue fracture for Hi-lock bolts of Ti-38644 high strength Ti-alloy has been investigated using SEM and EDS in order to reveal the microscopic characteristics of crack initiation and crack propagation, as well as the mechanism related with fatigue life enhancement. The fatigue fracture zone for Hi-lock bolt of Ti-38644 Ti-alloy can be divided into three parts: fatigue crack initiation zone, crack propagation zone and instant break zone. The fatigue cracks initiate from the surface of weak part under the bolt head, then radially propagate in matrix. The sizes of fatigue cracks display a transition from microscopic to macroscopic, once in the propagation zone. The fatigue band extension becomes the main mechanism, meanwhile, the typical features of cleavage fracture can be observed. The fatigue life for Hi-lock bolt of Ti-38644 Ti-alloy is significantly affected by deformation layer at the fillet, which may enhance the fatigue life-time for the Hi-lock bolts of Ti-38644 Ti-alloy with such deformation layer. The mechanism of strengthen anti fatigue has also been discussed by comparing the microstructure observation data and fatigue test results from different Hi-lock bolts of Ti-38644 Ti-alloy.

The dendritic mesoporous silica particles (DMSPs) with Y-type mesochannels were synthesized via an oil-water biphase stratification reaction with decahydronaphthalene as the upper oil phase. The spherical DMSPs were then characterized by means of TEM, SEM, Low-angle XRD, nitrigen adsorption/desorption and particle size distribution. Results show that the prepared particles presented an average particle size of 72±6 nm with a narrow size distribution; The DMSPs presented three-dimensional central-radial mesochannels with an average pore inner diameter of 7.7 nm; The formed mesopores presented the lack of long-range order. After polishing with DMSPs abrasives, the root-mean-square roughness of oxidized silicon workpieces reduced from 0.76 to 0.21 nm. The maximum asperity height in sectional profiles decreased from 1.48 to 0.50 nm, and the maximum valley depth reduced from 1.86 to 0.45 nm. An average removal rate of 187 nm/min was achieved. Furthermore, the interfacial friction and wear behavior and contact adhesion effect of DMSPs abrasives were also discussed.

The structure of the oxide scale on the as received hot-rolled bridge steel Q345q and the corrosion behavior of the steel Q345q with oxide scale in three simulated atmospheric environments in Northwest China were studied by XRD, scanning electron microscopy, electrochemical technique and wet-dry alternating corrosion test. The results show that the hot-rolled oxide scale composes mainly of Fe₃O₄ and Fe₂O₃, which is porous with cracks and other defects. After the dry-wet alternating accelerated corrosion test of the steel Q345q with oxide scale, although the corrosion weight loss is the highest in NaHSO₃ solution, the free-corrosion potential increases with the corrosion time, and the free-corrosion current density decreases in the later stage of corrosion. As far as the morphology of the rust layer and the ratio of γ/α* are concerned, the rust layer formed on the steel presents good stability; However, in deicing salt solution, the corrosion rate is the smallest, but the steel suffered mainly from Cl^--dominated pitting corrosion with the corrosion characteristics of "large cathode and small anode". Its corrosion products contain such as β-FeOOH and HFeCl₄(H₂O)₆, which results in loose rust layer with poor protectiveness and increased free-corrosive current density; In deicing salt+NaHSO₃ solution, both pitting corrosion and general corrosion occur. Due to the synergistic effect of Cl^- and HSO₃^-, the autocatalytic effect of a part of Cl^- is reduced, but most α-FeOOH is converted from β-FeOOH, which resulted in the poor protective rust layer.

The tribological behavior of TC11 Ti-alloy was studied via an MPX-2000 type friction and wear tester with TC11Ti-alloy as pin and GCr15 steel as disc in conditions of applying different loads and incorporating various nano-lubricants onto the interface of pin/disc. The surface morphology, cross-section morphology, composition and structure of worn TC11 Ti-alloy were comparatively characterized by means of scanning electron microscopy with energy dispersive spectroscope and X-ray diffractometer. The results show that tribo-layer of nano-particulates could form on the worn surface of TC11 Ti-alloy when different type of nanomaterials were incorporated onto the sliding interface of the tribo-pairs. The stability of the tribo-layer depends on its composition and the relative content of each component. The multi-layered graphene (MLG) containing tribo-layer possessed poor stability and readily damaged because of its low load-bearing capacity. The Fe₂O₃ containing tribo-layer possessed good stability under lower loads, resulting in the reduced wear and increased friction. The double-layered tribo-layer composed simultaneously of MLG and Fe₂O₃ possessed high stability, which can be ascribed to the good lubrication and load-bearing capacity. As a result, the friction and wear performance of TC11 Ti-alloy was markedly enhanced. Especially the double-layered MLG/Fe₂O₃ nano-particulate tribo-layer with Fe₂O₃-rich nanocomposite possessed higher stability and thus the tribological properties of TC11 Ti-alloy could be much effectively improved.

ML40Cr steel for 8.8-grade bolts of power transmission towers was selected as research object in this paper. Considering the fatigue reliability of the bolts fastened under different pre-stresses, tension-tension fatigue and symmetric three-point bending experiments were conducted to investigate the fatigue properties and fatigue crack propagation behavior of ML40Cr steel samples, respectively. The experimental results show that the fatigue limits for smooth samples and notched samples of the ML40Cr steel are 263 MPa and 95 MPa, respectively when the 50% of tensile strength was adopted as the mean stress with different stress amplitudes. The effect of the mean stress on the stress-fatigue life (S-N) curve of the ML40Cr steel samples was investigated by the effective stress method and the corresponding fatigue notch sensitivity 0.31 was obtained. According to the results of symmetrical three-point bending tests the Paris formula of ML40Cr steel for 8.8 bolts is fitted as \mathrm{d}a/\mathrm{d}N={\mathrm{10}}^{-\mathrm{10}}{\left(?K\right)}^{\mathrm{2.2}}. Mechanisms of notch fatigue strength and crack growth of the ML40Cr steel for the bolts were also discussed.

Zn particles were surface modified with polystyrene sodium sulfonate doped poly3, 4-ethylene dioxythiophene (PSS-PEDOT). The corrosion performance of the as modified Zn powder was investigated by means of immersion test in 3.5%NaCl (mass fraction) solution and scanning electron microscope, of which the corrosion current density was found one order of magnitude smaller than that of the blank Zn powder. Then, the anticorrosion performance of the coating composed of acrylic resin incorporated with the modified Zn powder was characterized by means of salt spray test and electrochemical impedance spectroscope. It follows that less corrosion of Zn particles on the coating surface was observed and the cathodic protection duration of the coating was prolonged by 20% in contrast with the one incorporated with blank Zn powder. The increased corrosion resistance of Zn particles and enhanced electrical connections that decreased the Zn reactivity was proposed as the possible mechanism of the improved anticorrosion performance of the coating incorporated with modified Zn powder.

Microstructure- and texture-evolution of Ti65 Ti-alloy plate were investigated, and the tensile deformation mechanism of the plate after heat treatment with different texture were discussed. The results show that heat treatment has a significant influence on the evolution of microstructure and texture of the plate. Equiaxed-, duplex- and lamellar-microstructure would be obtained after different heat treatment. The plate with equiaxed microstructure presented a B/T texture, while the c-axis of the α-phase and the rolling direction (RD) met at a 70°~90° angle; similar texture could be found in duplex- and lamellar-microstructure, meanwhile a new texture that the c-axis of the α-phase paralleled to RD could be found in the alloy. Room temperature tensile strength of plates with duplex microstructure could be enhanced by the dislocations and sub-structures, while had little effect on tensile properties at high temperature. Texture was found to be the main factor affecting the anisotropy of tensile properties of Ti65 plates, the plate would possess good tensile properties without obvious anisotropy in tensile strength after heat treatment of 980℃/1 h/AC+700℃/4 h/AC.

Solution temperature (T) sensitivity for the volume fraction (V) of primary α-phase in the α+β-phase field of two Ti750 alloys with 0.25 Mo and 1.0 Mo (mass fraction%) were comparatively investigated. The results show that the variation of volume fraction of primary α-phase with temperature seems to follow a negative power function curve, with a slow initial reduction and then rapid reduction with the increase of temperature for both alloys. The V-T curve for the alloy with 0.25% Mo showed a steeper slope compared with the alloy with 1.0% Mo, indicating that with the increase of Mo addition, the decrease of solution temperature sensitivity may emerge for the volume fraction of the primary α-phase in the α+β-phase field of Ti750 alloys. In the two alloys with the same volume fraction of primary α-phase, the Al concentration in the primary α-phase of the alloy with 1.0% Mo is higher than that of alloy with 0.25 % Mo. In other word, Mo indirectly increases the thermodynamic stability of the primary α-phase and thus reduces the temperature sensitivity of the volume fraction of α-phase in Ti750 alloy.