Abstract: Zeolite A was synthesized by hydrothermal crystallization using the acid-treated stellerite as raw material. The synthesizing process was examined by XRD and SEM. In this reaction process, the SiO2 and Al2O3 in solid phase were translated into the SiO2 and Al2O3 in the liquid phase continuously, when the acid-treated stellerite and NaAlO2 were dissolved. These phenomena indicate that the formation mechanism of zeolite A is the solution-mediated transport mechanism, because the formation of zeolite A is drived by the concentration supersaturation of the composition in liquid phase, and is transported by solution-media.
Abstract: The competitive adsorption of arsenate and chromate was conducted on the surface of hydroxy-Fe-montmorillonite complex. The effect of the initial concentration and the addition order of arsenate and chromate on their uptake by hydroxy-Fe-montmorillonite complex was investigated. The results show that competitive adsorption does not exist between arsenate and chromate on hydroxy-Fe-montmorillonite complex under experimental conditions. The addition of the secondary anion increases the adsorption of the first one to some extent and this increase is proportional to the initial concentration of the two anions. The addition order of arsenate and chromate influences their uptakes to a certain extent, especially on the surface of hydroxy-Fe-montmorillonite complex. This phenomenon is more obvious for chromate for its relative weak affinity for adsorption on these surfaces.
Abstract: Gold leaching from refractory Au ores using iodine and iodides was investigated. Thermodynamic analysis showed that the process is feasible. The technological parameters of iodine leaching were optimized. Comparing to the cyanidation process, iodine leaching gives better metallurgical performance, shorter leaching time and higher Au recovery. The Au recovery reached 95% after iodine leaching for 4 h, whereas the cyanidation process of 12 h gave a Au recovery of 80%.
Abstract: In order to improve the backfill slurry quality and guide the design of slurry pipeline transportation, the relationship between the size distribution feature parameters ∑△pi/di and the limit solid volume fraction was demonstrated. It is concluded that the size distribution is optimal while the solid volume fraction of the mixed slurry with thick and thin aggregates is maximal. An equation group was proposed to calculate the limit solid volume fraction.
Abstract: Taking the cutting excavation of Beijing-Qinhuangdao freeway slope as an example, the dynamic features and the distribution regularity of blasting vibration waves such as stress field, displacement field and velocity field were analyzed and the influence of blasting vibration on the mountainous freeway-cutting slope was studied by numerical simulation. The comparison of simulation results with in-situ measuring results shows that they are approximate.
Abstract: A airtight large-diameter urn was made in which electromagnetic radiation (EMR) antennae can be placed and the experimental system was set up that can detect EMR signals during gas flowing in coal. EMR spectrum analysis was done by Fourier transform when different kinds of gas under different pressure gradients flow in coal. The results show that frequency band of EMR produced by gas flowing is usually in low frequency and its main frequency band increases with the increase of pressure gradient. The higher the pressure gradient and the rate of gas flow, the more intensive the destruction of coal and the motion-electricity effect, and the higher the frequency of crack oscillation.
Abstract: Through a water simulation experiment, the influence of cross jet parameters on principle strain was studied. It is beneficial to the mixing effect by increasing the cross corner and momentum at outlet and keeping an appropriate distance between the two lances. The effects of different types of lances on the combustion rate of pulverized coal were researched in laboratory. The results show that the oxygen and coal double lances or the two coal double lances could obtain a higher combustion rate than any type of single lance. It is concluded that cross jet can achieve a good condition of heat transfer and mass transfer for the combustion of pulverized coal in front of a tuyere.
Abstract: Under the condition of realizing[S] ≤ 5×10-6 in molten steel, the reaction mechanism of refining de-sulphurization for the steel with the lowest surphur content was investigated by high temperature chemical dynamic experiment in 1 kg Si-Mo bar pipe-furnace. The reaction progression, rate constant, bottle neck in reaction, and affecting factors were determined.
Abstract: The heat transfer of mold flux in mold was investigated in laboratory. It was shown that with the increase in viscosity and solidification temperature of mold flux, the thermal conductivity and the heat flux density of flux were reduced, and the thermal resistance was increased. The thermal conductivity of mold flux between the mold and the solidified shell can be adjusted by changing the properties of mold flux.
Abstract: The effect of top slag composition on MnO-Al2O3-SiO2 inclusion composition was studied by controlling the condition of deoxidization and the composition of top slag in an experimental furnace in which the tire cord steel were melt. The Al2O3 content in the inclusion increased with the Al2O3 content of top slag increasing while the basicity of top slag was within 0.7-1.36. Plastic MnO-Al2O3-SiO2 inclusion existed while the Al2O3 content of top slag was below 8%. The composition of MnO-Al2O3-SiO2 inclusion can be controlled within the plastic area by controlling the condition of deoxidization and the composition of top slag.
Abstract: In order to meet the requirements of real time and dynamic reaction in a steelmaking-continuous casting scheduling system, the requirement model, static model and dynamic model of the system were built by united modeling language (UML), and the characters and key technologies in the modeling process were discussed. It is concluded that UML-based model can band structure and data together and describe system requirements precisely.
Abstract: The effect of hydrogen on the nanomechanical properties of passive films formed on 316 stainless steel was investigated by using nanoindentation and electrochemical testing techniques. The results show that the critical fracture load of passive films is reduced and the displacement excursion is decreased with the increase of the concentration of hydrogen. The reduction of radial breaking stress and elastic modulus of passive films is attributed to that hydrogen changes the structure of passive films.
Abstract: Ceramic layers were obtained by the micro-arc oxidation technology on LY12 aluminum alloys. The wear resistance properties of ceramic layers at room temperature were tested and analyzed. The experimental results indicate that the surface wear profile of micro-arc oxidized ceramic layers is regular and the hardness of ceramic layers is 10 times more than that of substrate. It is concluded that the wear resistance capability and hardness of aluminum alloys can be remarkably improved by the micro-arc oxidation technology.
Abstract: The microstructure near the penetrated hole of a 60 steel target was analyzed by launching a navy 37 gun. It is shown that the melting of 93 W alloy occurs under the high pressure in the process of penetration because there is a component of 93 W alloy on the surface of the penetrated hole. An adiabatic shear band formed along the main shear stress around the penetrated hole is approximately consistent with the direction of plastic deformation slip lines in static state. Non-homogenous deformation inside the adiabatic shear band causes microcracks and micropores. Two kinds of adiabatic shear bands were found, including the deformed band and the phase-transformed band.
Abstract: LiFePO4 was synthesized by solid state reaction. A reversible capacity of 125-138 mAh/g was achieved under a low current density of 20 mA/g at room temperature. In order to improve the electrochemical performance of the material, Li(Fe0.8Mn0.2)PO4 and LiFePO4/C were prepared, respectively. The charge-discharge experiment of the samples showed that the capacities were 145 mAh/g and 144 mAh/g, respectively. They both had a good voltage plateau and exhibited wonderful high current properties.
Abstract: Butyraldehyde glycol acetal was synthesized from butyraldehyde and glycol in the presence of TiSiW12O40TiO2. The factors influencing the yield of product and the optimum reaction condition were discussed. The optimum condition is the molar ratio of butyraldehyde to glycol is 1:1.5, the quantity of catalyst is equal to 0.5% in mass fraction, and the reaction time is 1.0 h. TiSiW12O40/TiO2 is an excellent catalyst to synthesize butyraldehyde glycol acetal and the yield can be up to 81.9%.
Abstract: The relationship between speed and tension was analyzed theoretically. The speed balance and rolling tension during continuous rolling were studied. It was recognized that steady continuous rolling may be sorted into independent mill rolling with tension, but the tension and speed of stack must be identical to that in front and back frames. When the gap of rolls changes with tension, with the tension, there is a transition steady period of the cross section change of rolling stack between the frames, while the speeds of the cross sections are equal, but the theory of volume flow equality should not be used.
Abstract: Rolling model of H beam was established through MSC Marc/AutoForge FEA software and the rolling process was simulated to solve the defect problem for H beam. The metal flow in rolling process was simulated by thermo mechanical coupled elastoplastic element and the pressure distribution on web was given. The simulation results are agreeable with the measuring data.
Abstract: The 3-dimensional finite element models of tool and workpiece in the skew rolling process were built up with ANSYS/LS-DYNA software. Computer simulations on the ladder shaft in skew rolling under different parameters were conducted. The stress and strain of workpiece in skew rolling were obtained and the forming mechanism of interior defect in the billet was studied. An explanation to the mechanism of Mannesmann effect is that low cycle fatigue damage, in the condition of deformation with large plastic strain, occurs inside the workpiece due to the alternately-changing stress and strain.
Abstract: The transfer and balance of heat during the cold milling of aluminum foil were analyzed. A viewpoint about them was proposed. The surface temperature of aluminum foil was measured in three ways with different open nozzles. With the combination of theory analysis and experiment, the power of heat absorption of the aluminum foil and the working roll was acquired respectively, and the partition coefficient between the aluminum foil and the working roll was also calculated for the first time. The results show that the partition coefficient of the aluminum foil varies from 0.11 to 0.33, while that of the working roll from 0.67 to 0.89. The partition coefficient of the working roll increases with the cooling ability intensifies.
Abstract: In order to accomplish the quantitative evaluation of strip profile, a flatness recognition and evaluation system was proposed, which combines a pattern recognition model based on the fuzzy classification principle and a flatness evaluation model by multi-grade statistics. This system was tested by the data measured from 2030 mm cold tandem mills and a good stage-by-stage result was achieved.
Abstract: The magnetic dipole model for two adjacent parallel cracks with rectangular shape was established. The relation between the magnetic flux leakage signals caused by two adjacent parallel cracks with rectangular shape on a ferromagnetic material surface and the crack-to-crack distance was clarified. The depth of the smaller crack can be evaluated by considering an effect that the amplitude of leakage flux decreases as the depth ratio of two cracks and the crack-to-crack distance increase. A method based on the analysis of the vector locus consisting of tangential and normal components of the magnetic flux leakage signals was proposed as an alternative to analyzing the waveform. Some experimental results show that the evaluated crack depth is in good agreement with the actual one.
Abstract: A viable alternative to adjust speed over a wide range at minimal cost using a doubly fed induction generator for wind turbines was introduced. The vector control system by DFIG mathematic models was analyzed. Three kinds four-quadrant power converters were discussed. During a low speed, the pitch angle is a constant, wind turbines keep on the optimum speed ratio between the pitch and wind so as to absorb the maximum energy. During a high speed, wind turbines absorb or release partial energy, and the mechanical stress were less.
Abstract: The performance of a proton exchange membrane fuel cell (PEMFC) stack was investigated at different ambient temperatures and humidities. The results show that the relative humidity and the temperature of the surrounding air significantly affect the performance of the PEMFC stack, and the maximum output power of the PEMFC stack increases sharply with the increase of relative humidity. While the relative humidity is less than 30%, or the ambient temperature is below 10℃, the performance of the PEMFC stack deteriorates.
Abstract: Aimed at the disadvantages of the traditional energy supply, a method to transfer energy by microstrip antennas was proposed. The characteristics of microstrip antennas were introduced, and the microstrip antenna used in a monitoring system was designed. An experiment for the microstrip antenna was carried out. Its attenuation of transmission, efficiency and matching conditions were analyzed. It was shown that under the conditions of close range and low power, using microstrip antennas to transfer energy is feasible.
Abstract: The dislocation and morphology dislocation density in the hot strip of low carbon steel after finishing pass produced by CSP were investigated by using H-800 transmission electron microscopy and positron annihilation technology. The experimental results showed that the dislocation density increased with the cumulative reduction increased. The dislocation density after the finishing pass is larger than that of the hot strip produced by the conventional technique.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
