Based on the mineralogical characterization for the polymetallic sulfide ore, the way to improve silver recovery was studied. The results showed that silver was the most valuable metal whose grade was 448.82 g/t Ag, while 0.118% Cu, 1.65% Pb and 1.06% Zn may be comprehensively utilizated. The main silver-bearing minerals were argent and aregentite which accounted for 87.18% of total silver. Argentite and other metal minerals were distributed in the gangue minerals in complex forms. Argentite grains of 33.76% minus 50 μm indicated that a fine grinding scheme was necessary to enhance the degree of dissociation, and meanwhile selective grinding must be considered to prevent a complete grinding of coarse grains. The optimum regrinding fineness in the Cu flotation was determined as 73% minus 37 μm, while grains of 68.5% minus 74 μm in one-stage grinding remained unchanged as much as possible. Consequently, silver recovery increased to 2.68%, as well as the content of Pb simultaneously decreased from 7.26% to 2.68% in the Cu concentrate. From the lead pyrometallurgical point of view, recovering larger amounts of silver and lead at the expense of decreasing the grade of lead to a suitable level is not only economically viable for the plant, but also convenient for subsequent processing. Silver and lead recovery increased to 13.18% and 12.58%, respectively, while the Pb grade decreased from 53.1% to 46.12% for the Pb concentrate.

The effects of CaO and Na₂CO₃ on the reduction of high silicon iron ores at 1 250 °C were studied. The experimental results showed that the metallization rate was significantly hindered by the addition of CaO and Na₂CO₃, particularly at the early stage of roasting, compared to the rate without additives. In the absence of additives, iron oxides were quickly reduced to metallic iron, and fayalite was difficult to form. When CaO and Na₂CO₃ were added, the low reducible iron-containing silicate compounds formed and melted, subsequently retarding the metallization process. The inhibition of Na₂CO₃ was more noticeable than that of CaO, and higher Na₂CO₃ doses resulted in stronger inhibition of the increased metallization rate. However, when Na₂CO₃ was added prior to CaO, the liquid phase formed, which facilitated the growth of the metallic phase. To reinforce the separation of the metallic phase and slag, an appropriate amount of liquid phase generated during the reduction is necessary. It was shown that when 10% CaO and 10% Na₂CO₃ were added, a high metallization rate and larger metallic iron particles were obtained, thus further decreasing the required Na₂CO₃ dosage.

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na₂CO₃ and CaCO₃ additives. The functions of Na₂CO₃ and CaCO₃ during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO₃ also decreases the P content of direct reduced iron (DRI) by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na₂CO₃ promotes hematite reduction and improves the iron recovery (ε_Fe) by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε_Fe in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.

We investigated synthesis and characterization of melamine-urea-formaldehyde (MUF) microcapsules containing n-alkane mixture as phase change core material for thermal energy storage and low- temperature protection. The phase change microcapsules (microPCMs) were prepared by an in situ polymerization using sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) as emulsifiers. Surface morphology, particle size, chemical structure, and thermal properties of microPCMs were, respectively, characterized by using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). Low-temperature resistance performances were measured at -15, -30, -45, and -60 °C after microPCMs were coated on a cotton fabric by foaming technology. The results showed that spherical microPCMs had 4.4 μm diameter and 100 nm wall thickness. The melting and freezing temperatures and the latent heats of the microPCMs were determined as 28.9 and 29.6 °C as well as 110.0 and 115.7 J/g, respectively. Encapsulation of n-alkane mixture achieved 84.9 %. TGA analysis indicated that the microPCMs had good chemical stability below 250 °C. The results showed that the microencapsulated n-alkane mixture had good energy storage potential. After the addition of 10 % microPCMs, low-temperature resistance duration was prolonged by 126.9%, 145.5%, 128.6%, and 87.5% in environment of -15, -30, -45 and -60 °C, respectively as compared to pure fabric. Based on the results, phase change microcapsule plays an effective role in lowtemperature protection field for the human body.

Thermodynamic stability, microvoid distribution and phases transformation of natural pozzolana opal shale (POS) were studied systematically in this work. XRD analysis showed that opal-CT, including microcrystal cristobalite and tridymite, is a major component of POS. DTA and FT-IR indicated that there were many hydroxyl groups and acid sites on the surface of amorphous SiO₂ materials. FE-SEM analysis exhibited amorphous SiO₂ particles (opal-A) covering over stacking sequences microcrystal cristobalite and tridymite. Meanwhile, MIP analysis demonstrated that porosity and pore size distribution of POS remained uniform below 600 °C. Because stable porous microstructure is a key factor in improving photocatalyst activity, POS is suited to preparing highly active supported.

The properties of Al/conductive coating/α-PbO₂-CeO₂-TiO₂/β-PbO₂-WC-ZrO₂ composite anode for zinc electrowinning were investigated. The electrochemical performance was studied by Tafel polarization curves (Tafel), electrochemical impedance spectroscopy (EIS) and corrosion rate obtained in an acidic zinc sulfate electrolyte solution. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDXS) were used to observe the microstructural features of coating. Anodes of Al/conductive coating/α-PbO₂-CeO₂-TiO₂/β-PbO₂, Al/conductive coating/α-PbO₂-CeO₂-TiO₂/β-PbO₂- WC, Al/conductive coating/α-PbO₂-CeO₂-TiO₂/β-PbO₂-ZrO₂, and Pb-1%Ag anodes were also researched. The results indicated that the Al/conductive coating/α-PbO₂-CeO₂-TiO₂/β-PbO₂-WC-ZrO₂ showed the best catalytic activity and corrosion resistant performance; the intensity of diffraction peak exhibited the highest value as well as a new PbWO₄ phase; the content of WC and ZrO₂ in coating showed the highest value as well as the finest grain size.

Mg_0.2Zn_0.8O (MZO)/La_0.67Ca_0.33MnO (LCMO) heterostructure was deposited on p⁺-Si substrates by sol-gel spin coating technique. The Ag/MZO/LCMO/p⁺-Si devices exhibit a bipolar, reversible, and remarkable current-voltage characteristic at room temperature. An obvious multilevel resistive switching effect is observed in the devices. The dominant conduction mechanism of the devices is trap-controlled space charge limited current. The resistance ratio of high resistance state and low resistance state of the devices is about six orders of magnitude, and the degradation is invisible in the devices after 250 successive switching cycles. The present results suggest that the Ag/MZO/LCMO/p⁺-Si devices may be a potential and multilevel candidate for nonvolatile memory application.

The microstructure, tensile property and wear resistance of 7075 aluminum matrix composite reinforced with TiC particles prepared by in-situ reaction casting were investigated. The effect of TiC reinforcement on wear behavior was analyzed. The wear mechanism was also discussed. A micro-mechanism model of reaction kinetics for synthesis of TiC was acquired. Results show that TiC could increase the tensile and yield strength, but decrease the elongation. Besides, TiC particles improve the property of wear resistance of 7075 aluminum alloy. The wear mechanisms include abrasive wear and adhesive wear in wear test process.

The yttrium iron garnet (YIG) thin films prepared by the sol-gel method and rapid thermal annealing (RTA) process for integrated inductor are investigated. The X-ray diffraction (XRD) results indicate that the YIG film annealed above 650 °C is poly-crystalline with single-phase garnet structure. Moreover, it can be found that the initial permeability μ _i, saturation magnetization M _S and coercivity H _c of these YIG films increase with increasing RTA temperature. Low temperature annealing after crystallization can further improve the magnetic properties of YIG film. Thereby, a planar integrated inductor in the presence of Si substrate/SiO₂ layer/Y_2.8Bi_0.2Fe₅O₁₂ thin film/Cu spiral coil structure is fabricated successfully by the standard IC processes. Due to the magnetic enhancement originated from YIG film, the inductance L and quality factor Q of the inductor with YIG film are improved in a certain frequency range.

The synthesis of Bi₂S₃ hierarchical nanostructure was reported by a solvothermal reaction using ethylene disulfhydrate as the sulfur source and chelating reagent. The as-synthesized samples were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and photoluminescence (PL). The XRD, Raman, and XPS data confirmed that the as-synthesized sample belongs to orthorhombic phase Bi₂S₃. The SEM observations displayed that Bi₂S₃ hierarchical nanostructure assembled from nanorods. A 410 nm ultraviolet photoluminescence (PL) emission of as-synthesized Bi₂S₃ was observed when the sample was excited with wavelength of 320-330 nm. The Bi₂S₃ hierarchical nanostructure also shows a significant enhancement of photocatalytic capability toward degrading methyl orange (MO) under UV light, the photodegradation of MO reaches 95% within 180 min.

Octahedral CoO with nanostructures decorated with Ag nanoparticles was prepared via a facile solvothermal approach. After being annealed at 500 °C for 1 h, an electrochemical capacitor material of Co₃O₄ decorated with Ag₂O was obtained. The cyclic voltammetry and galvanostatic charge-discharge were used to evaluate the electrochemical properties of the as-prepared products. The results indicated that the as-prepared samples exhibited fine pseudo-capacitive performance, and the surface modifications of Ag₂O can significantly increase the capacitance of the Co₃O₄ material. The specific capacitance of Ag₂O/Co₃O₄ composite electrode was up to 217.6 F·g⁻¹, which was 3.35 times as high as that of pure Co₃O₄. Moreover, Ag₂O/Co₃O₄ composite showed an excellent cycle performance, and 65.3% of specific capacitance was maintained after 200 cycles.

The atomic geometry, structure stability, electronic and magnetic properties of VSe₂ were systematically investigated based on the density functional theory (DFT). Varying from 3D to 2D four VSe₂ structures, bulk 2H-VSe₂ and 1T-VSe₂, monolayer H-VSe₂ and T-VSe₂ are all demonstrated as thermodynamically stable by lattice dynamic calculations. More interestingly, the phase transition temperature is dramatically different due to the lattice size. Finally, owing to different crystal structures, H-VSe₂ is semimetallic whereas T-VSe₂ is totally metallic and also they have different magnetic moments. Our main argument is that being exfoliated from bulk to monolayer, 2H-VSe₂ transforms to T-VSe₂, accompanied by both semimetallic-metallic transition and dramatic magnetic moment variation. Our calculations provide a novel structure phase transition and an efficient way to modulate the electronic structure and magnetic moment of layered VSe₂, which suggests potential applications as high-performance functional nanomaterial.

Hydraulic characteristic is a good indication of binder hydration, which determines the strength development of cemented paste backfill (CPB). Therefore, the hydraulic characteristic should be communicated with the mechanical property to provide an advanced knowledge that can help mine workers make a rational strategy and reduce the mining cycle. An experimental program was performed to obtain the hydraulic (monitored by suction and volumetric water content) and mechanical properties (unconfined compressive strength (UCS) test) of CPB at the 28 days curing age. According to the monitoring and testing results, the relationships between the hydration reaction rate and volumetric water content (VWC), suction and VWC, suction and UCS were established. The hydration degree showed a liner rise as the VWC decreased. Curves of the VWC and UCS were featured with a nonlinear reduction and nonlinear growth (both are exponential functions) as the suction rising, respectively. These established relationships validated the strong correlative mechanism of hydraulic and mechanics behavior for CPB. Also, the results of the present research indicated that the hydraulic characteristics and mechanical property were strongly coupled. These correlations and couplings will be of great importance to understand the hardening process of CPB and bring to a safe CPB field operation.

This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement (SAC)-based planting cementitious material. The effect of natural zeolite on the performance of SAC-based planting material was investigated. The water-retention performance, porosity, compressive strength, and alkalinity had been tested and TG-DSC analysis had been adopted in this paper. Experimental results showed that zeolite was effective to improve the water-retention capacity and 10%, 20% and 30% natural zeolite increased the pore volume of the hardened pastes by 10.6%, 26.0%, and 38.6%, especially pore size below 0.1 μm was increased by 9.7%, 26.2% and 17.5%. And 10% zeolite was beneficial to the compressive strengths of cementitious material and 1, 3, and 28 d compressive strength reached up to 35.9, 55.0, 80.3 MPa. Furthermore zeolite decreased the alkalinity of pore fluid of hardened cementitious material, while the addition of zeolite reached up to 30%, the alkalinity of pore fluid of hardened cementitious material decreased by 8.9%. Therefore zeolite was suitable for improving the performance of SAC-based planting cementitious material.

As a decorative material, magnesium oxychloride cement was used as a photocatalyst supporter to purify the pollutants indoors. Due to excellent adsorption properties of activated carbon (AC), the photocatalytic composties, TiO₂/AC, were prepared and introduced into the porous magnesium oxychloride cement (PMOC) substrate to composite a sort of photocatalytic cementitious material (PCM). The optimal composite processes were assessed by gas chromatograph, using toluene as the target. By comparing the perspective of toluene purification and thorough decomposition, it can be found that the optimal mass ratio for TiO₂/AC composites is 4/25, and the heat treatment to TiO₂/AC sample at 350 °C can play the optimal synergetic role of adsorbents in photocatalytic process. The synergistic effect of TiO₂, AC and magnesium oxychloride cement (MOC) was also evaluated by gas chromatograph. One-take molding process was adopted to introduce the TiO₂/AC into PMOC substrate, and its optimal mass fraction was 4 wt%, while the appropriate density of substrate was 0.35 g/cm3. Toluene degradation showed that the prepared PCM can degrade pollutants efficiently. The appropriate treatment process of TiO₂/AC, mass of TiO₂/AC, substrate density, and stable pore structure should be coordinated to maximize the adsorption-photodegradation performance. The combination of photocatalytic materials, adsorbents, and building materials provided a new idea for the application of photocatalysis.

Composition, morphology, and structure of hydration products in hardened pastes of three kinds of blended cement (cement-silica fume, cement-quartz powder and cement-silica fume-quartz powder) hydrated under different curing regimes (standard curing, 90 °C steam curing, 200 °C and 250 °C autoclave curing) were investigated by X-ray diffraction and field emission scanning electron microscope equipped with EDAX system. Results showed that the main hydration products in three kinds of hardened pastes under standard curing condition are all C-S-H gels, CH, and AFt. Under 90 °C steam curing condition, the main hydration products of cement-silica fume and cement-silica fume-quartz powder are C-S-H gels, whereas those of cement- quartz powder are C-S-H and CH. Under 200 or 250 °C autoclave curing condition, no obvious crystallized CH phase is found in hardened pastes of three kinds of blended cement, and C-S-H gels are transformed into one or more crystalline phases such as tobermorite, jennite, and xonotlite. The chemical composition and morphology of these crystalline phases depend on the composition of mixture and autoclave temperature.

Discarded train brake shoes mainly consist of steel-backed friction material. To be better reutilized, its essential features and its interaction in cement-based material need to be studied. Consequently, particle size analysis, SEM, IR and TGA were used to investigate two types of waste brake shoes, i e, mechanical grinding friction reclaimed material of waste brake-shoe (G-FRMWBS) and pyrolysis-friction reclaimed materials of waste brake-shoe (P-FRMWBS). The latter exhibited less organic content, larger range of particle size distribution and smaller medium particle diameter. Both types contained inorganic particles of spherical and irregular shapes, striped with steel fiber. Upon isometric substituting fine aggregates, G-FRMWBS lifted the strength of mortar effectively that was increased by 16.6% and 17.5% when the replacing rate was 5%; the value went up to 19.2% and 19.2% when the replacing rate was 10%. Moreover, inclusion of FRMWBS enhanced the chloride penetration resistance, and optimized the pore characteristic and ITZ (interfacial transition zone) as well.

The influences of rare earth elements (cerium and lanthanum) on the microstructure and phases of Al-3.0 wt%Mg alloys used for electromagnetic shielding wire were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The mechanical properties and electrical resistivity were also investigated. The results indicated that a certain content of rare earth could improve the purification of the aluminum molten, enhance the strength, and reduce the electrical resistivity of Al-3.0 wt%Mg alloys. The strength reached the top value when RE content was 0.3 wt% while the alloy with 0.2 wt% RE addition had the smallest electrical resistivity. The elongation varied little when RE addition was no more than 0.2 wt%. But the excessive addition of rare earth would be harmful to the microstructure and properties of Al-3.0 wt%Mg alloys.

The microstructure and mechanical properties of low carbon bainite high strength steel plate were studied via different cooling paths at the pilot scale. There was a significant increase in mechanical properties, and notably, the yield strength, tensile strength, and toughness at -40 °C for the tested steel processed by ultra-fast cooling were 126 MPa, 98 MPa and 69 J, respectively, in relation to steel processed by accelerated cooling. The ultra-fast cooling rate not only refined the microstructure, precipitates, and martensiteaustenite (M/A) islands, but also contributed to the refinement of microstructure in thick plates. The large size M/A constituents formed at lower cooling rate experienced stress concentration and were potential sites for crack initiation, which led to deterioration of low-temperature impact toughness. In contrast, the acicular ferrite and lath bainite with high fraction of high-angle grain boundaries were formed in steel processed by ultra-fast cooling, which retarded cleavage crack propagation.

The main objective of this paper is to evaluate the effects of asphalt concrete types on the microstructural characteristics at high-temperature. Suspend-dense structure and Skeleton-dense structure were selected to investigate the deformation of pavement at meso-scale. The internal microstructures of typical asphalt concretes, AC, SUP and SMA, were scanned by X-ray CT device, and microstructural changes before and after high-temperature damage were researched by digital image processing. Adaptive threshold segmentation algorithm(ATSA) based on image radius was developed and utilized to obtain the binary images of aggregates, air-voids and asphalt mastic. Then the shape and distribution of air-voids and aggregates were analyzed. The results show that the ATSA can distinguish the target and background effectively. Gradation and coarse aggregate size of asphalt mixtures have an obvious influence on the distribution of air-voids. The movements of aggregate particles are complex and aggregates with elliptic sharp show great rotation. The effect of gradation on microstructure during high-temperature damage promotes the research about the failure mechanism of asphalt concrete pavement.

Atmospheric corrosion behavior of pure Al 1050A, 5A02 and 6A02 aluminum alloys exposed to a tropical marine environment for 4 years was investigated. Synergetic effect of Cl^- deposition rate and time of wetness resulted in an abnormal increase in weight loss and a significant fluctuation in corrosion rate. Pitting corrosion occurred on the three metals. Pits on 5A02 alloy were easy to initiate and inclined to propagate laterally to form higher corrosion area and shallower corrosion pits, while pits on 6A02 alloy presented the opposite appearances. This was further confirmed by the cyclic polarization experiments.

Aiming at overcoming the low plasticity of magnesium alloy at room temperature, we researched viscous warm pressure bulging(VWPB) of AZ31B magnesium alloy based on the excellent thermal stability of viscous medium under the warm forming condition. The potential improvements of plastic deformation ability and forming quality of AZ31B magnesium alloy are expected with the aid of thermal characteristics of viscous medium. During bulging process the velocity field variation and pressure stress field distribution of viscous medium are observed at different temperatures through which the effect of temperature on the mechanical property of viscous medium and AZ31B magnesium alloy are analyzed. The results show that the formability of AZ31B magnesium alloy increases first and then decreases as the temperature increases and it is the best at 200 °C. On the other hand, the viscous medium which can build non-uniform pressure stress field also exhibits a good flow property at elevated temperature, and it is helpful to improving the formability of AZ31B magnesium alloy.

The spark plasma sintering (SPS) method was used to study the mechanism of reaction interface between Zr and Ti₃AlC₂ with electric current going through it. It was found that electric current greatly reduced the bonding temperature of Zr and Ti₃AlC₂. By the micro-structure analysis of the interface through SEM/EDS, it was found that Al atoms diffused from the Ti₃AlC₂ substrate into the Zr side and reacted with Zr to form the Zr-Al compounds at the interface, which is the strengthening mechanism of Ti₃AlC₂-Zr bonding. The thickness of reaction layers (Zr-Al alloy) was from 0.879 to 13.945 mm depending on different sintering condition. Current direction, heating rate, soaking time, pulse patterns all influenced the diffusion of Al atoms which affected the joining quality of Zr and Ti₃AlC₂.

Titanium matrix composites reinforced with α-Al₂O₃ and TiB₂ particles were fabricated by in situ synthesis from a Ti-Al-B₂O₃ system. The reaction processes and microstructure were analyzed by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the reactions in the Ti-Al-B₂O₃ system can occur spontaneously and consist of three steps: 1) 15Al + 7B₂O₃ → 7α-Al₂O₃ + AlB₁₂ + 2B; 2) 14B + 2Al → AlB₁₂ + AlB₂ and 3) 7Ti + AlB₁₂ + AlB₂ → 7TiB₂ + 2Al. The final reinforcements were composed of α-Al₂O₃ and TiB₂ particles, which were uniformly distributed in the titanium matrix.

Ultra fast cooling (UFC) processing after hot deformation was conducted on X70 and X80 linepipe steels. Tensile and charpy impact properties of both steels have been investigated in this work. The results have shown that the mechanical properties satisfy all the standard requirements of the X70 and X80 steels. UFC results in a presence of microstructure containing quasi polygonal (QF), acicular ferrite (AF) and granular bainite (GB). The alloying elements and UFC enhance the strengthening contribution caused by solid solution, dispersion, dislocation and precipitation strengthening. The size and distribution of precipitates in the linepipe steels are fine and dispersed. MA is also homogeneously dispersed due to UFC. Average grain size in the X80 steel is finer than that in the X70 steel. The volume fractions of secondary phases in the X80 steel are greater than those in the X70 steel. The X80 steel remains finer and more dispersed precipitates compared to the X70 steel. As a result, the tensile properties of X80 steel are higher than those of X70 steel. The Charpy absorbed energies of X70 and X80 steels at -10 °C reached 436 and 460 J, respectively. They reached 433 and 461 J at -15 °C, respectively. This is mainly attributed to the presence of larger amounts of AFs in the X80 steel. A microstructure of AF for the X80 steel results in combining high strength and high toughness.

High strength, ductility, and superplasticity Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr (wt%) alloy was prepared by sequentially applying rapid solidification, extrusion, and reciprocating extrusion (REX). The microstructure of the alloy after 2-pass REX consisted of fine grains smaller than 0.7 μm and nanometer strengthening particles. The refined grains resulted from recrystallization during which the nanometer particles played an important role in restrain grain growth. The mechanical properties of the material were investigated at room and elevated temperatures. High tensile yield strength of 336 MPa and elongation of 27% were obtained at room temperature. At elevated temperatures, the highest elongation of 270% was obtained at 250 °C and an initial strain rate of 3.3×10^-3 s^-1, and LTS and HSRS were achieved. The high strength, ductility, and superplasticity were attributed to the refined unique microstructure.

The isothermal compression tests were carried out on Gleeble-3500 thermal-mechanical simulation machine in a temperature range of 298-473 K and strain rate range of 0.001-10 s^-1. The experimental results show that the flow stress data are negatively correlated with temperature for temperature softening, and the strain rates sensitivity of this composite increases with elevating temperature. Based on the experimental data, Johnson-Cook, modified Johnson-Cook and Arrhenius constitutive models were established. The accuracy of these three constitutive models was analyzed and compared. The results show that the values predicted by Johnson-Cook model could not agree well with the experimental values. The prediction accuracy of Arrhenius model is higher than that of Johnson-Cook model but lower than that of the Modified Johnson-Cook model.

The hardness, the tensile and the high-cycle fatigue (HCF) performances of 7075 aluminum alloy were investigated under temper T651, solution treated at 380 °C for 0.5 h and aged at different temperatures (150, 170, 190 °C) for 10 hours. The optimal microstructures and the fatigue fracture surfaces were observed. The results show that the hardness and the tensile performances are at their optimum at T651, but the fatigue life is the shortest. The hardness and the elongation are the lowest after solution treatment. With the aging temperature increasing (150-190 °C), the HCF is improved. The crack is initiated from the impurity particles on the subsurface. Treated at 170 °C,the area of the quasi-cleavage plane and the width of parallel serrated sections of the crack propagation are the largest. With increasing aging temperature, the dimple size of finally fracture surfaces becomes larger and the depth deeper.

The element Ni in the Mg₂Ni alloy is partially substituted by M (M = Cu, Co, Mn) in order to ameliorate the electrochemical hydrogen storage performances of Mg₂Ni-type electrode alloys. The nanocrystalline and amorphous Mg₂₀Ni_10-xM _x (M = None, Cu, Co, Mn; x = 0-4) alloys were prepared by melt spinning. The effects of the M (M = Cu, Co, Mn) content on the structures and electrochemical hydrogen storage characteristics of the as-cast and spun alloys were comparatively studied. The analyses by XRD, SEM and HRTEM reveal that all the as-cast alloys have a major phase of Mg₂Ni but the M (M = Co, Mn) substitution brings on the formation of some secondary phases, MgCo₂ and Mg for the (M = Co) alloy, and MnNi and Mg for the (M = Mn) alloy. Besides, the as-spun (M = None, Cu) alloys display an entirely nanocrystalline structure, whereas the as-spun (M = Co, Mn) alloys hold a nanocrystalline/amorphous structure, suggesting that the substitution of M (M = Co, Mn) for Ni facilitates the glass formation in the Mg₂Ni-type alloys. The electrochemical measurements indicate that the variation of M (M = Cu, Co, Mn) content engenders an obvious effect on the electrochemical performances of the as-cast and spun alloys. To be specific, the cyclic stabilities of the alloys augment monotonously with increasing M (M = Cu, Co, Mn) content, and the capacity retaining rate (S20) is in an order of (M = Cu) > (M = Co) > (M = Mn) > (M = None) for x≤1 but changes to (M = Co) > (M = Mn) > (M = Cu) > (M = None) for x≥2. The discharge capacities of the as-cast and spun alloys always grow with the rising of M (M = Co, Mn) content but first mount up and then go down with increasing M (M = Cu) content. Whatever the M content is, the discharge capacities are in sequence: (M = Co) > (M = Mn) > (M = Cu) > (M = None). The high rate discharge abilities (HRDs) of all the alloys grow clearly with rising M (M = Cu, Co) content except for (M = Mn) alloy, whose HRD has a maximum value with varying M (M = Mn) content. Furthermore, for the as-cast alloys, the HRD is in order of (M = Co) > (M = Mn) > (M = Cu) > (M = None), while for the as-spun (20 m·s^-1) alloys, it changes from (M = Co) > (M = Mn) > (M = Cu) > (M = None) for x = 1 to (M = Cu) > (M = Co) > (M = None) > (M = Mn) for x = 4.

The ultrasonic pulse signal resonance features in layered carbon fiber reinforced plastic (CFRP) within voids were researched. The frequency domain model of acoustic wave propagation in multilayered medium was established. Then the reflection coefficient of multilayered CFRP within voids was numerically calculated. The results are as follows. When the CFRP laminate is tested by ultrasonic whose center frequency is close to the CFRP inherent resonant frequency, the ultrasonic may generate resonance phenomenon in CFRP. If CFRP contains evenly distributed voids, the frequency of resonant signal and its amplitude all decrease with the increase of porosity. For the thick section CFRP within local concentrated voids, the local concentrated voids near testing surface will cause signal frequency reduction and the decrease of its amplitude. But the voids which exist in layers far away from testing surface almost have no influence on signal resonance. The ultrasonic pulse echo testing was conducted for thick section CFRP specimen. The analysis results of testing signals were in accordance with the results of the numerical calculation, showing that the reflection coefficient frequency response model can effectively explain the ultrasonic resonance phenomenon in layered CFRP within voids.

A reconstruction method is proposed for the polyurethane foam and then a complete numerical method is developed to predict the effective thermal conductivity of the polyurethane foam. The finite volume method is applied to solve the 2D heterogeneous pure conduction. The lattice Boltzmann method is adopted to solve the 1D homogenous radiative transfer equation rather than Rosseland approximation equation. The lattice Boltzmann method is then adopted to solve 1D homogeneous conduction-radiation energy transport equation considering the combined effect of conduction and radiation. To validate the accuracy of the present method, the hot disk method is adopted to measure the effective thermal conductivity of the polyurethane foams at different temperature. The numerical results agree well with the experimental data. Then, the influences of temperature, porosity and cell size on the effective thermal conductivity of the polyurethane foam are investigated. The results show that the effective thermal conductivity of the polyurethane foams increases with temperature; and the effective thermal conductivity of the polyurethane foams decreases with increasing porosity while increases with the cell size.

Multi-walled carbon nanotubes (MWCNTs) reinforced hollow glass microspheres (HGMs)/epoxy syntactic foam was fabricated. The effects of ultrasonication on the density, compression strength, and water absorption properties were studied. Better dispersed MWCNTs can be obtained after ultrasonication treatment, but an increasing viscosity will lead to a larger amount of voids during syntactic foam preparation especially when the content of HGMs is more than 70 vol%. The existing voids will decrease the density of epoxy syntactic foam. However, the ultrasonication does not change the compression strength much. Ultrasonication treatment will decrease the water absorption content due to the better dispersion and hydrophobic properties of MWCNTs. But a significant increase of water absorption content occurs when HGMs is more than 70 vol%, which is attributed to the higher viscosity and larger amount of voids.

The nature of the pull-out system of carbon nanorope/polyethylene (CNRP/PE) composite is studied by using molecular dynamics approach. The deformation of the CNRP/PE composites in pull-out process is exhibited. The influence of twisting deformation on the interfacial interaction of the composites is investigated. The results show that the energy of the pull-out system is conserved; and the interfacial bonding is weak resulting in a sliding failure of the CNRP inside PE matrix.

A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact (CAI) tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.

A novel hybrid type photosensitive resin for stereolithography in 3D printing was prepared with bisphenol A type epoxy diacrylate (EA-612), tripropylene glycol diacrylate (TPGDA), ethoxylated trimethyolpropane triacrylate(EO₃TMPTA), cycloaliphatic diepoxide(ERL-4221), polycaprolactonepolyol(Polyol-0301),1-hydroxy-cyclohphenyl ketone(Irgacure184), and a mixture of triarylsulfonium hexafluoroantimonate salts (Ar₃SS_bF₆). The novel hybrid type photosensitive resin was the photosensitive resin of an epoxy-acrylate hybrid system, which proceeded free radical polymerization and cationic polymerization in ultraviolet (UV) laser. Cuboid parts and double-cantilever parts were fabricated by using a stereolithography apparatus with the novel hybrid type photosensitive resin as the processing material, and the dimension shrinkage factor and the curl factor were tested. The shrinkage factor was less than 2.00%, and the curl factor was less than 8.00%, which showed that the accuracy of the fabricated parts was high with the photosensitive resin for stereolithography in 3D printing.

In order to improve poly-β-hydroxybutyrate (PHB) production in activated sludge, the anaerobic/aerobic alternative operating sequencing batch reactor (SBR) process was applied in this paper to accumulate PHB. Effects of nutritional conditions and carbon concentration on PHB accumulation were studied. Results indicated that PHB accumulation reached the highest level and accounted for 11.2 % under anaerobic condition for phosphate limitation and 20.84 % under aerobic condition for nitrogen and phosphate limitation of mixed liquor suspended solid (MLSS), respectively. In addition, 4 g/L was proved to be the optimum carbon concentration in both anaerobic and aerobic experiments, and the PHB accumulation reached 17.1 % (anaerobic, phosphorus limitation) and 60.4 % (aerobic, nitrogen and phosphorus limitation) of MLSS, respectively. PHB could be successfully extracted with sodium hypochlorite and chloroform method from the activated sludge. In addition, the infrared spectrum showed that the PHB sample extracted was of high purity.

The potential application of a designed self-assembly peptide CH₃CO-Pro-Thr-Phe-Cys-Phe-Lys-Phe-Glu-Pro-NH₂ (named as P1) as a carrier of 5-Fluorouracil (5-Fu) for controlled release in vitro was studied. 5-Fluorouracil (5-Fu) was selected as a representative anticancer drug due to its extensive use in treating digestive system cancer and breast cancer. The interaction between P1 and 5-Fu was detected by fluorescent quenching experiments and atomic force microscopy (AFM). The quenching mechanism of 5-Fu and P1 system was dynamic by performing fluorescent quenching experiments at different temperatures. The thermodynamic analysis demonstrated that the interaction between 5-Fu and P1 was hydrophobic interaction. The complexes prepared by the interaction between peptide and 5-Fu appeared as large granular particles of about 20 nm in height under AFM (denoted as5-Fu-P1), 24 times larger than the original 5-Fu particles. According to the results, an interaction model was proposed. Furthermore, 5-Fu-P1 complexes exhibited an efficient controlled release of 5-Fu in vitro. The research suggested that P1 might be a candidate carrier for drug delivery, providing a substitution agent for 5-Fu.