Abstract:Cu/Al bi-metal plates were produced by asymmetrical cold rolling and subsequent annealing treatments were applied to the as-rolled bi-metal plates. The effects of annealing temperature on the bond strength, locations and compositions of de-bonding failure layer development of the samples were investigated by using Instron tensile testing machine, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). The study revealed that diffusion annealing generally did not improve the bond strength of Cu/Al bi-metal plates. The thickness of diffusion layers reached 7.31 μm when annealed at 350 ℃ for 2 hours and 15.53 μm when annealed at 500 ℃ for 2 hours. Through microstructural inspection, it was found that fractures of the as-peeled materials appeared in the Al-rich layer near the middle of the diffusion layers. Further investigations indicated that the major compositions of fracture layers were CuAl and CuAl2 phases. Brittle intermetallic phases generally determined the bond strength of Cu/Al bi-metal plates. Furthermore, bond strength was also related to the original cracks and no-bonding area formed during cold rolling. When annealing temperature fell below 350℃, Cu/Al bi-metal plates displayed relatively better bonding properties.

Abstract:By using the impact abrasive wear testing machine to simulate the actual working conditions of high manganese steel parts, the wear mechanism of high manganese steel under different impact loads was investigated with scanning electron microscopy and other equipment. The result indicates the grain of the high manganese steel is smaller after the heat treatment process, which firstly heats the high manganese steel to 550 ℃ for 1.5 hours, secondly heats it to 650 ℃ for 2 hours, and then heats it to 1 080 ℃ for 2 hours, and quenches it at last. The relate impact load of 2J/mm2 is the critical impact load of high manganese steel. High manganese steel fully plays its work hardening effect when the relate impact load is above the critical impact load. There are two wear mechanisms: cutting mechanism and pit mechanism. After impact abrasive wear test, there are a large number of slip bands in high manganese steel, and the slip bands' density increases when the relate impact load increases. When the relate impact load is 2 J/mm2, the cross slip is found in the grains.

Abstract:The microstructures and mechanical properties of SiCp/2024 composite processed by repetitive upsetting and extrusion (RUE) were investigated through tensile testing, optional microscopy(OM),scanning election microscopy(SEM) and transmission election microscopy(TEM). The results showed that the matrix was effectively refined during the repetitive deformation, the distribution of SiC particles was improved, and some SiC particles were broken by shear force. Due to alternating shear deformation, the dislocation on the matrix was reorganized and annihilated, and then some small sub-grains were formed. Compared with the as-extruded SiCp/2024 composite, the tensile strength increased from 271 MPa to 378 MPa after 4 passes, and the yield strength increased from 203 MPa to 260 MPa. The fracture of the composite after RUE mainly resulted from interfacial debonding and SiC particles breakage.

Abstract:The glass transition involves a minor change in the internal energy, and yet the physical and mechanical properties of a glass change dramatically. In order to determine the evolution of the atomic structure through the glass transition, in-situ synchrotron X-ray scattering measurements as a function of temperature on metallic glass were conducted. It is found that the thermal expansion at the atomic level is smaller than the macroscopic thermal expansion, and significantly increases above the glass transition temperature (Tg). It is also found that the relative change of the quantity(N represents the number of atom pairs), with significantly longer interatomic distances for the nearest atomic pairs, increases above Tg. These phenomena consist with the interconnecting zone connected tight-banded-cluster amorphous model. This model contains essentially three major parts: (I) clusters with tight bonding; (II) loosely bonded free volume regions between clusters; and (III) interconnecting zones, which interconnect the clusters.

Abstract:In-situ and three-dimension carbon coated LiFe0.96Ti0.02PO4/C cathode material was synthesized in solid-state method with polyvinyl alcohol (PVA) as the carbon source and supervalent Ti4+ as doping ion. The microstructures were characterized with XRD, SEM, TEM and EDS. The electrochemical performances were investigated with cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge test. The results show that the pyrolytic carbon of PVA possesses excellent electronic conductivity and can be the best candidate for coating LiFePO4 easily in an in-situ and three-dimensional way. Through the comprehensive modification of in-situ and three-dimensional carbon coating and Ti4+ doping, the active material possesses excellent low temperature and high rate electrochemical performances without reducing its intrinsic high temperature structure stability. The discharge capacities at the rate of 0.1 C under 0 ℃ and 5 C under 30 ℃ are 128.7 mAh/g and 97.4 mAh/g, respectively.

Abstract:The mechanical properties of Recycled Aggregate Concrete (RAC) with different mixing approaches were comparatively investigated. Based on the experiments on the Interfacial Transition Zone (ITZ) of RAC by nanoindentation technique and scanning electron microscopy, the results indicate that, for the new ITZ with Normal Mixing Approach (NMA), the elastic modulus distribution appears to decrease significantly from the old paste matrix surface, while for the new ITZ with Two-Stage Mixing Approach (TSMA), there is no obvious trend indicating that the elastic modulus increases or decreases with the increase of distance. For the old ITZ, the elastic modulus increases as the distance increases from original aggregate surface. The TSMA can improve the microstructures of the new ITZ by reducing the volume fraction of voids and calcium hydroxide. Correlating the nanomechanical properties of ITZ and microstructure with the compressive strength of RAC, it can be concluded that TSMA can enhance the mechanical properties of RAC by improving the mechanical properties and microstructure of the new ITZ.

Abstract:Electrical pulse technology has been researched to accelerate the sulfate attack in cement based materials under different temperatures, but the acceleration mechanism of sulfate attack by action of electrical pulse is not involved. By comparing accelerated sulfate attack by electrical pulse with conventional attack, the distribution and migration of sulfate ion under the action of electrical pulse were studied, and the microstructure of erosion product was tested by using X-ray diffraction (XRD). The test result indicated that more sulfate ion was transferred into sample by action of electrical pulse, and sulfate ion was enriched in an area within 2 cm at the cathode. The corrosion product before 28 days is ettringite and gypsum. It is concluded that the sulfate attack of cement based materials is accelerated under the action of electrical pulse by the speed migration and reaction of sulfate ion.

Abstract:The effects of ordinary Portland cement (OPC) on setting time, mechanical behaviors and working performances, including water absorption, softness efficiency, corrosion-resistance and arasion-resistance of ceramic gypsum model, were investigated. The mechanisms were characterized with the measurements of X-ray diffraction, scanning electron microscopy (SEM) and DSC/TG. The results showed that the amount of water demand was reduced and the setting time was shortened by adding OPC. Besides, the strength at the later stage of hydration was significantly increased by the amount of OPC rising which remarkably enhanced the performances of corrosion-resistance, softness efficiency and arasion-resistance. The mechanisms indicated that CaSO4·2H2O(DH), AFt and C-S-H gel were the main hydration production. The interconnection between needle, clavuligerus DH and acicular AFt crystals together with the filling of C-S-H into pore space led to a more compacted crystal-gel microstructure, which enhanced the macro-performances of gypsum hardened paste. In addition, DTA-TG results indicated that the dehydration temperature of DH was also improved from 140 ℃ to 150 ℃ due to the more compact microstructure of gypsum hardened paste. What's more, the morphology of gypsume was modified to be grainy, noodles-shape and stumpy.

Abstract:A finite element model of rod porcelain insulator containing semi-elliptical surface crack was established in ANSYS solid modeling method. Three dimensional 20 node isoparametric degenerative singular elements were used to simulate the stress singularity of the crack tip, and the stress intensity factor (SIF) of crack front on porcelain insulator under bending was calculated in 1/4-node method. The rule of crack size, location and various load versus KI was obtained. The results have shown that, under the same condition, the maximum of crack front SIFs appears at the deepest point between the lower flange port and the first umbrella skirt, and the value of KI decreases with the increase of crack shape ratio, while increases with the increase of crack depth and load.

Abstract:Ti/steel clad plate is usually prepared by high energy plasma spray technology, which is hard to avoid pores and cracks degrading the performance of Ti film. Therefore, several kinds of representative commercial organic coatings and nano-modified acrylic coating were used for the hole sealing treatment. The surface structure of Ti film and combination with organic coatings were observed by SEM. Moreover, electrochemical test and salt spray tests were conducted to compare different corrosion resistances of Ti/steel clad plates with organic coatings. In conclusion, the results showed that nano-modified acrylic coating was more suitable as a hole sealing coating for Ti/steel clad plates due to the synergistic protection of sprayed Ti film and nano-modified acrylic coating.

Abstract:The electrodeposition laws of Ni-Mo alloy in alkaline citrate solution were studied with potentiostatic deposition and cyclic voltammetry. Potentiostatic deposition indicated that the presence of MoO42- could reduce the deposition overpotential of Ni, and the deposition current efficiency of Ni-Mo alloy was lower than Ni in Ni deposition bath as the potential moved negatively. Cyclic voltammetry indicated that, as the content of Ni2+ increased, both the first reduction peak for Ni deposition and the deposition peak of Ni-Mo alloy moved to more positive potentials, and as the content of MoO42- increased, the deposition peak of Ni-Mo alloy moved to more negative potentials.

Abstract:In order to find a new type of PLLA high temperature crystallization nucleating agent, three kinds of palladium compounds, palladium chloride, Bis (triphenylphosphine) palladium (II) dichloride and 1,4-Bis (diphenylphosphino) butane-palladium (II) chloride were selected to add to PLLA, and PLLA / palladium compounds were prepared by melt blending based on different contents of palladium compounds. This work presented the effect of palladium compounds on the crystallization behavior and crystalline structure of PLLA with differential scanning calorimetry (DSC), polarizing optical microscope (POM) and X-ray diffraction (XRD).The results revealed that palladium chloride, Bis (triphenylphosphine) palladium (II) dichloride hindered the crystallization and 1,4-Bis (diphenylphosphino) butane-palladium(II) chloride promoted the crystallization. In the cooling crystallization process, when the amount of 1,4-Bis (diphenylphosphino) butane-palladium (II) chloride was 0. 8%, the corresponding crystallization peak temperature (Tc) rose from 103.92 ℃ to 126.57 ℃ and crystallization enthalpy (△Hc) increased from 31.52 J/g to 52.82 J/g, respectively. In the study of isothermal crystallization, the results showed that the Avrami exponent n was between 3 and 4, which implied the crystal morphology was spherulitic, and this means the crystal growth manner, crystalline structure and crystal form did not change. All these suggest that 1,4-Bis (diphenylphosphino) butane-palladium(II) chloride is a new type of PLLA nucleating agent, and more research is needed to understand its nucleation mechanism.

Abstract:This paper calculated the phase diagrams of nine ternary systems including K+, Mg2+, Na+, Cl- and NO-3 and their binary systems by using a Pitzer-Simonson-Clegg thermodynamic model. The binary model parameters were fitted with experimental water activity and osmotic coefficient data, and the ternary model mixture parameters were obtained by regressing the experimental solubility data of the ternary salt-water systems. All model parameters and equilibrium constants of the solid phase were expressed as the functions of temperature. Furthermore, the positions of invariant points over the range of temperature from 273.15 K to 364.15 K of the ternary system KCl-KNO-3-H2O were accurately predicted, and the predicted vapor pressures over aqueous solutions which are saturated with the invariant points of this system were in good agreement with literature data. And the water activities of the saturated solution of the ternary systems KNO3-NaNO3-H2O and NaCl--NaNO3-H2O at 363.15 K were predicted and compared with experimental data. On the basis of these, we neglected the quaternary model parameters and just used the binary and ternary parameters to predict the isotherms of the quaternary systems K+, Mg2+∥Cl-, NO-3-H2O, K+, Na+∥Cl-, NO-3-H2O, Mg2+, Na+∥Cl-, NO-3-H2O and K+, Na+, Mg2+∥NO-3-H2O, and to predict the vapor pressure of saturated solution of the system K+, Na+∥Cl-, NO-3-H2O over the temperature range from 278.15 K to 323.15 K. The predicted values were in good agreement with experimental data.

Abstract:This paper studied the technology of removing calcium and magnesium ions from manganese sulfate leaching solution prepared in two-ores method with poor pyrolusite. The results are as follows: using 30% P204 added 70% sulfonated kerosene as the extraction solvent, saponification rate 60%, temperature 25 ℃, phase ration(O/A)3∶1, and keeping pH of solution about 6.0 at the beginning, the extraction yields of the calcium and magnesium ions are 99.37% and 90.62% respectively. Calcium and magnesium ions content can be reduced to less than 100 ppm, and high purity manganese sulfate solution from which calcium and magnesium ions have been removed deeply can be obtained. In the loaded organic phase via 4.0 mol/L sulfuric acid stripping, metal ions were stripped completely. The economically feasible process of using the leaching purification liquid and stripping liquid to preparation of high purity manganese compounds was designed, and the whole process of integrated application of manganese sulfate leaching solution was achieved.

Abstract:To investigate the effect of modification by SDS on the roasting-assisted clinoptilolite of physic-chemical properties and ammonia nitrogen removal performance from secondary effluent, natural clinoptilolite was modified by SDS-firing. The results have shown that SDS decoration can greatly improve the denitrification performance of roasted zeolite. SDS modified roasted zeolite has a better removal rate of nearly 98.79%, an increase of about 30% over the roasted samples. By scanning electron microscopy (SEM) and energy spectrum analysis (EDS), X-ray diffraction (XRD), specific surface area and pore size analysis, infrared spectra analysis (IR), and cation exchange capacity (CEC), the characterizations of the zeolite before and after being modified were analyzed. SDS modification made the surface of the zeolite particles loosen, there were more channels, and pore volume and pore diameter were increased. The silica alumina ratio of zeolite decreased, the Na ion content of the composite zeolite increased, the diffraction peak intensity weakened, and the internal chemical groups changed, further enhancing the cation exchange capacity.

Abstract:In order to decrease the energy consumption in municipal sewage treatment process, a collaborative optimization method of biological and ecological combined process was proposed. Collaborative optimization included two main aspects. On the one hand, to reduce the treatment load and energy consumption, the effluent concentration of biological unit was controlled as the permitted influent concentration of ecological unit by distributing the pollutant load dynamically between biological and ecological treatment units in different seasons. On the other hand, in the biological unit, an optimal equation was established with DO concentration, up-to-standard discharge and minimum energy consumption of aeration as the control variable, constraint condition and objective function, respectively. The equation adopted optimization method, and oxygen switch function was introduced to reflect the influence of DO concentration on the maximum specific rate of pollutant degradation quantitatively. Furthermore, by solving the optimal equation in a sewage treatment plant, the pollutants could be removed after 2.3 hours' aeration in the condition of keeping DO value at 4.58 mg/L, and the energy consumption was 31.7 kWh. It shortened the aeration time of 1.7 h and saved energy of 28.3 kWh compared with operating biological unit only, which suggests remarkable energy-saving effect. Finally, the effectiveness of the optimization method was verified by one month's data of a sewage treatment plant.

Abstract:Water, algae and sediment were sampled in the Zhushan Bay of the Taihu Lake, where partial black and odorous water frequently occurs, and incubated as the following combinations: sediment-water-algae, water-algae and sediment-water. Physical environmental indicators, blackening and odorous matter, and conventional indicators of the three water samples were monitored to reveal the influence of sediment on the formation of algae-induced partial black and odorous water. It was shown that sediment would make black and odorous water occur ahead of time. On the one hand, sediment promoted the formation of dimethyltrisulfide（DMTS） and further transformation. On the other hand, sediment promoted the formation of inorganic sulfur compounds and increased the concentration of sulfide and Fe2+ in the overlying water, which made the water turn black ahead of time and aggravated the water black. During the period of water blackening, sulfide and Fe2+ concentration increased by 0.63 mg/L and 0.10 mg/L in the sediment-water-algae sample, compared with the water-algae sample. The massive accumulation and death of blue-green algae made a strong anaerobic reductive environment, which induced nutrients in sediments to be released to the overlying water, making the water environment deteriorate sharply.

Abstract:To elucidate the effect of heavy metals on enzymes production and the characteristics of enzymatic degradation in the process of biodegradation of polycyclic aromatic hydrocarbons (PAHs) by Bacillus sp. P1, enzyme variations (the content and composition of proteinase, the activities of catechol 2,3-dioxygenase in crude enzymes and enzymatic degradation ability) in the process of phenanthrene degradation were investigated in the presence of Cd(II). The results showed that Cd (II) would inhibit enzyme productions and enzymatic degradation. As Cd(II) increased from 0 to 150 mg/L, the amount of extracellular and intracellular proteinase (absolute integrated optical density analyzed by Gelpro) decreased from 8.37×106, 1.54×107 to 5.49×106, 6.01×106, respectively. As Cd(II) increased from 0 to 300 mg/L, the activities of catechol 2,3-dioxygenase in extracellular enzymes (EE) and intracellular enzymes (IE) decreased from 266.96 to 38.93 U/mg, 886.30 to 290.26 U/mg, respectively. The degradation rates of Phenanthrene (PHE) by EE and IE decreased from 79.86% to 64.59%, 87.96% to 74.83%, respectively. These results suggest that Cd (II) can cause enzyme variation, thus affecting the phenanthrene biodegradation by Bacillus sp. P1.

Abstract:Taking the city cluster of the Xiangjiang River basin for example, the paper proposed a new approach to associate the regional ecological footprint with the socio-economic development. First, on the basis of the traditional emergetic ecological footprint model, the changing processes of the local ecological footprint in the six cities of the Xiangjiang River basin were calculated and analyzed by dividing the ecological footprint accounts into the local productive resources accounts and the local waste emission accounts. Then, the correlation degree between the ecological footprint and the socio-economic indicators was calculated with the method of mathematical statistics. The results showed that the average ecological footprint was 18.35 times of the average ecological carrying capacity from 1999 to 2008, which demonstrated that the city cluster of the Xiangjiang River basin was in a situation of ecological deficit. The largest ecological deficit occurred in Yueyang City while the smallest occurred in Changsha City among this city cluster. The plus-driving effects of the socio-economic development to the ecological footprint was much stronger than the minus-driving effect. Economic development model and food demand were the principal factors which prompted the growth of the local ecological footprint. Therefore, it should be paid full attention to the driving effect of the economic model to the ecological environment in the process of the economic structure transition.

Abstract:Model-based optimal control study of the six-tank integrative activated sludge process was carried out, and two step running time control strategies based on the cycle running feature of six-tank process were proposed, i.e. Fix_time strategy and NO3_control strategy. The step running time of the former was fixed, while that of the latter was controlled by SNO3 and its variation rate detected by the on-line sensors in the anoxic tanks. There were 7 parameters in Fix_time strategy and 6 parameters in NO3_control strategy needed to be determined. The two strategies were analyzed in multi-objective optimization method considering effluent quality and energy consumption simultaneously. The results showed that NO3_control strategy was more adaptive than Fix_time strategy because it could meet the time-demand of denitrification, and therefore, NO3_control strategy had better effluent quality with lower energy consumption. This research indicates that NO3_control strategy can improve the performance of the six-tank integrative activated sludge process.

Abstract:The natural height slope and elevation of the topography were reconstructed with computer to do terrain construction experiment, objective analysis of the Zhuzhou landscape layout was conducted with the terrain construction simulation data, and a guide of practical significance in city construction under the background of city development was proposed.