2025-04-09 2008, Volume 15 Issue 2

  • Select all
  • Xin-ming Zhang , Ling-ying Ye , Ying-wei Liu , Yu-xuan Du , Zhi-hui Luo

    Fine-grained 01420 Al-Li alloy sheets were produced by thermo-mechanical processing based on the mechanism of particle stimulated nucleation of recrystallization. The thermo-mechanically processed sheets were observed to contain layers of different microstructures along the thickness. The precipitate behavior of the second phase particles and their effects on the distribution of dislocations and layered recrystallized grain structure were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffractometry(XRD). The formation mechanism of the gradient particles was discussed. The results show that after aging, a gradient distribution of large particles along the thickness is observed, the particles in the surface layer(SL) are distributed homogeneously, whereas those in the center layer(CL) are mainly distributed parallel to the rolling direction, and the volume fraction of the particles in the SL is higher than that in the CL. Subsequent rolling in the presence of layer-distributed particles results in a corresponding homogeneous distribution of highly strained regions in the SL and a banded distribution of them in CL, which is the main reason for the formation of layered grain structure along the thickness in the sheets.

  • Jiang-hai You , Sheng-dan Liu , Xin-ming Zhang , Xiao-yan Zhang

    The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test, optical microscopy, scanning electron microscopy and transmission electron microscopy. For the Zr-free alloy, the strength increases to the highest value at 20 s with transfer time, and then decreases slightly. The elongation decreases slowly with transfer time within 20 s, and more rapidly after 20 s. For the Zr-containing alloy, prolonging transfer time within 20 s results in slight decrease in the strength and elongation, and rapid drop of which is observed after 20 s. For the Zr-free alloy, prolonging transfer time can increase the percentage of intergranular fracture, which is mainly caused by wide grain boundary precipitate free zone. The failure mode of the Zr-containing alloy is modified from the predominant transgranular void growth and intergranular fracture to transgranular shear and intergranular fracture with increase in the transfer time, which is attributed to the wider grain boundary precipitate free zone and coarse equilibrium η phases in the matrix.

  • Xin-ming Zhang , Wen-hui Liu , Jian-guo Tang , Ling-ying Ye

    The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of ϑ=45° (ϑ is the angle between grain boundary direction and X-axis) is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture.

  • Zi-qian Huang , Yue-hui He , Hai-tao Cai , Cong-hai Wu , Yi-feng Xiao , Bai-yun Huang

    Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and 1 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.

  • Song-jiang Ma , Sheng-lian Luo , Hai-hui Zhou , Ya-fei Kuang , Xiao-hui Ning

    Platinum(Pt)/nanofibrous polyaniline(PANI) electrode was prepared by pulse galvanostatic method and characterized by scanning electron microscopy. The electrochemical behavior of L-cysteine at the Pt/nanofibrous PANI electrode was investigated by cyclic voltammetry. The results indicate that the pH value of the solution and the Pt loading of the electrode have great effect on the electrocatalytic property of the Pt /nanofibrous PANI electrode; the suitable Pt loading of the electrode is 600 μg/cm2 and the suitable pH value of the solution is 4.5 for investigating L-cysteine oxidation. The L-cysteine sensor based on the Pt/nanofibrous PANI electrode has a good selectivity, reproducibility and stability. The Pt/nanofibrous PANI electrode is highly sensitive to L-cysteine, and the linear calibration curve for the oxidation of L-cysteine can be observed in the range of 0.2–5.0 mmol/L.

  • Wen-jun Gong , Guang-ri Xu , Yi-jun Zhang , Yu-ping Zhang , Seong-ho Choi , Kwang-pill Lee

    Photopolymerized sol-gel(PSG) columns were prepared using methacryloxypropyltrimethoxysilane as the monomer, toluene as the porogen and hydrochloric acid as the catalyst. Four different photoinitiators such as benzoin methyl ether, Irgacure 819, Irgacure 1700 and Irgacure 1800 were comparatively used in the reaction solution in the presence and absence of sodium dodecyl sulfate. The above eight solutions were respectively irradiated at 365 nm for 5–10 min in each capillary (75 μm inside diameter) to prepare the porous monolithic sol-gel column by a one-step, in situ, process. The chromatographic behavior of the eight PSG columns were comparatively studied, all of which exhibit reversed-phase character. Using these columns, several neutral compounds, namely thiourea, benzene, toluene, ethyl benzene, biphenyl and naphthalene can be separated from mixtures with a largest column efficiency of 74 470 plate/column for thiourea. Addition of sodium dodecyl sulfate in the polymerization process has a significant influence on the morphology and migration time.

  • Yu-hua Wang , Ye Lan , Chuan-bing Huang

    The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings. The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage, solution pH value and shaking time were determined by batch experiments. The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation tailings as adsorbent. The methods, such as zeta potentials, specific surface area measurements and the analysis of adsorption kinetics, were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings. The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb2+ ions. The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions. These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings. Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model, and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation tailings.

  • Xue-feng Cao , Li-min Zhang , Yue-hua Hu , Chang-miao Liu , Kui Ouyang

    N, N-diethyl dodecyl amine(DEN12) was synthesized from dodecyl amine, formic acid and acetic aldehyde. The collecting property of DEN12 on diaspore, kaolinite and illite was investigated by flotation test and infrared spectrum. The results show that in the presence of 2.0×10−4 mol/L DEN12, the recoveries of kaolinite and illite are all higher than 78% and the recovery of diaspore is 50% in the pH range of 5.5–6.0. The mass ratio of Al2O3 to SiO2 in concentrate obtained from separation artificial mixture is higher than 10, suggesting that DEN12 can be used as a collector to separate the aluminosilicates from diaspore in bauxite ores at the pulp pH below 8. The measurements of the infrared spectrum approve that the action between aluminosilicates and tertiary amine collector is strong electrostatic adsorption and that of diaspore is weak electrostatic adsorption.

  • Xiao-wen Liu , Min Hu , Yue-hua Hu

    The effects of the cell parameter and chemical composition on the surface charge properties of five kinds of different colour montmorillonites were studied. The results indicate that the surface isoelectric point(IEP) of the montmorillonite shows positive correlation with the mass fractions of Fe2O3 and K2O, but it has little relation to the mass fractions of other chemical compositions. At around pH=6.8, the surface zeta potential of the montmorillonite shows the negative relationship with the mass fractions of Fe2O3 and MgO, but it does not linearly correlate to the mass fractions of other chemical compositions. Cell parameter(b0) of the montmorillonite expresses negative linear relationship with mass fractions of K2O and Na2O, so does c0sin β with mass fractions of SiO2 and Fe2O3. And there is no specific relationship between b0 and IEP of different montmorillonites, but there is positive correlation between c0sinβ and IEP of different montmorillonite samples.

  • Jie Li , Yu-yun Wu , Yan-qing Lai , Wei Liu , Zhi-gang Wang , Jie Liu , Ye-xiang Liu

    Two finite element(FE) models were built up for analysis of stress field in the lining of aluminum electrolysis cells. Distribution of sodium concentration in cathode carbon blocks was calculated by one FE model of a cathode block. Thermal stress field was calculated by the other slice model of the cell at the end of the heating-up. Then stresses coupling thermal and sodium expansion were considered after 30 d start-up. The results indicate that sodium penetrates to the bottom of the cathode block after 30 d start-up. The semi-graphitic carbon block has the largest stress at the thermal stage. After 30 d start-up the anthracitic carbon has the greatest sodium expansion stress and the graphitized carbon has the lowest sodium expansion stress. Sodium penetration can cause larger deformation and stress in the cathode carbon block than thermal expansion.

  • Ya-jie Zheng , Fa-xin Xiao , Yong Wang , Chun-hua Li , Wei Xu , Hong-sheng Jian , Yu-tian Ma

    Copper electrolyte was purified by copper arsenite that was prepared with As2O3. And electrolysis experiments of purified electrolyte were carried out at 235 and 305 A/m2, respectively. The results show that the yield of copper arsenite is up to 98.64% when the molar ratio of Cu to As is 1.5 in the preparation of copper arsenite. The removal rates of Sb and Bi reach 74.11% and 65.60% respectively after copper arsenite is added in electrolyte. The concentrations of As, Sb and Bi in electrolyte nearly remain constant during electrolysis of 13 d. The appearances of cathode copper obtained at 235 and 305 A/m2 are slippery and even, and the qualification rate is 100% according to the Chinese standard of high-pure cathode copper(GB/T467-97).

  • Xiang-yang Zhou , Shan-ni Li , Jie Li , Ye-xiang Liu

    The effects of polyurethane sponge pretreatment and slurry compositions on the slurry loading in precursor were discussed, and the performances of stainless steel foams prepared from precursors with different slurry loadings and different particle sizes of the stainless steel powder were also investigated. The experimental results show that the pretreatment of sponge with alkaline solution is effective to reduce the jam of cells in precursor and ensure the slurry to uniformly distribute in sponge, and it is also an effective method for increasing the slurry loading in precursor; the mass fraction of additive A and solid content in slurry greatly affect the slurry loading in precursor, when they are kept in 9%–13% and 52%–75%, respectively, the stainless steel foam may hold excellent 3D open-cell network structure and uniform muscles; the particle size of the stainless steel powder and the slurry loading in precursor have great effects on the bending strength, apparent density and open porosity of stainless steel foam; when the stainless steel powder with particle size of 44 μm and slurry loading of 0.5 g/cm3 in precursor are used, a stainless steel foam can be obtained, which has open porosity of 81.2%, bending strength of about 51.76 MPa and apparent density of about 1.0 g/cm3.

  • Ze-qiang He , Li-zhi Xiong , Wen-ping Liu , Xian-ming Wu , Shang Chen , Ke-long Huang

    The SnO2-polyaniline(SnO2-PAn) composite was prepared by microemulsion polymerization method using aniline, ammonium peroxodisulfate and SnO2 as starting materials. The SnO2-PAn composite was characterized by X-ray diffractometer, scanning electron microscope and electrochemical techniques. The results show that PAn in the composites is amorphous. PAn formed in the reaction is deposited preferentially on the SnO2 particles, giving a SnO2-PAn composite, in which SnO2 is coated with PAn. SnO2-PAn composite shows a reversible capacity of 657.6 mA·h/g and the capacity loss per cycle is only 0.092% after 80 cycles, suggesting that SnO2-PAn composite is a promising anode material for lithium ion batteries.

  • Xi-bing Li , Liang Hong , Tu-bing Yin , Zi-long Zhou , Zhou-yuan Ye

    In order to investigate the relationship between bar diameter and loading rate of the split Hopkinson pressure bar(SHPB) setup under the failure of rock specimen and realize the medium strain rate loading of specimen, new SHPB setups with different elastic bar’s diameters of 22, 36, 50 and 75 mm were constructed. The tests were carried out on these setups at different loading rates, and the specimens had the same diameter of elastic bars and same ratio of length to diameter. The test results show that the larger the elastic bar’s diameter is, the less the loading rate is needed to cause specimen failure, they show good power relationship, and that under the same strain rate loading, specimens are broken more seriously with larger diameter SHPB setup than with smaller one.

  • Xi-bing Li , Qi-sheng Wang , Jin-rui Yao , Guo-yan Zhao

    Based on the measured displacements, the change laws of the effect of distance in phase space on the deformation of mine lane were analyzed and the chaotic time series model to predict the surrounding rocks deformation of deep mine lane in soft rock by nonlinear theory and methods was established. The chaotic attractor dimension(D) and the largest Lyapunov index(Emax) were put forward to determine whether the deformation process of mine lane is chaotic and the degree of chaos. The analysis of examples indicates that when D > 2 and Emax>0, the surrounding rock’s deformation of deep mine lane in soft rock is the chaotic process and the laws of the deformation can still be well demonstrated by the method of the reconstructive state space. Comparing with the prediction of linear time series and grey prediction, the chaotic time series prediction has higher accuracy and the prediction results can provide theoretical basis for reasonable support of mine lane in soft rock. The time of the second support in Maluping Mine of Guizhou, China, is determined to arrange at about 40 d after the initial support according to the prediction results.

  • Zhou-yuan Ye , Liang Hong , Xi-ling Liu , Tu-bing Yin

    The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads. It is resumed that rock contains many microstructures and a structure of Bingham. The microstructure consists of two embranchments that are the unit of a spring and a gliding slice in series and the unit of a spring and a cementation bar in series, the two units connect each other in parallel. These microstructures are arranged disorderly or in the order of a certain state. A certain distribution of microstructures represents one type of rock. Two kinds of rock’s constitutive relationship were deduced by using the model. One is the model in which many parallel microstructures and a structure of Bingham connect in series. And it is used to homogeneous rock. The other is the model in which many microstructures and a structure of Bingham connect in series. And it is used to the rock with much crack or microcrack in a certain direction. The two kinds of constitutive relationship were verified by the studied cases. The constitutive model of rock built by using mechanics elements is verified to be reasonable. Moreover, different types of rocks may be described with mechanics elements with different distributions.

  • Zun-zhong Zhang , Lian-xing Gu , Chang-zhi Wu , Yi Shao , Jian-rong Xu , Jian-ping Zhai , Yuan-chuan Zheng , Jun-hua Tang , Chuan-sheng Wang , Jin-zhu San

    Based on the detailed petrographic study, the characteristics of source region of the Weiya gabbro and tectonic implications were studied. The results show that the gabbroic rock consists mainly of gabbro, with less amount of ultra-mafic rocks. The ultra-mafic rocks show cumulate texture and are gradually transitional contact with gabbro, indicating that they are cumulate products of parental magma. The ultra-mafic rocks consist mainly of spinel periodite and spinel clinopyroxenite. The former is mainly composed of olivine (65%–70%), spinel (10%–15%), hornblende (5%–10%) and phlogopite (5%–10%); the latter consists mainly of clinopyroxene (70%–80%), spinel (15%–20%) and phlogopite (0–10%), with minor amounts of carbonate (0–2%). No olivine or orthopyroxene is found. The gabbro is composed mainly of clinopyroxene (35%–40%), plagioclase (An 55–65, 40%–45%), hornblende (5%–15%), with variable amounts of carbonate (0–5%). Petrographic observations show that the source region of the Weiya gabbroic rock is water-rich due to intensive intra-continental A-type subduction occurring in this region during late Permian to early Triassic.

  • Li-xiong Kuang , Jian-hua Guo , Tai-zhu Huang

    The reservoir conditions, oil and gas charge history and accumulation phases were studied for Yingshan Formation of Yuqi block, and an oil and gas accumulation model was established by using the techniques of reservoir prediction, fluorescence thin section and fluid inclusion analysis under the guidance of the theories of oil and gas accumulation. The results indicate that the main rock types in Yingshan Formation are micrite and calcarenite. The carbonate reservoirs are of cave, fracture-pore and fracture types, and their physical properties are intermediate; there are at least four oil/gas charges, i.e. late Hercynian, Yanshanian, early Himalayan and middle Himalayan (Cenozoic). The most important charge periods are late Hercynian, early Himalayan and middle Himalayan; the oil and gas accumulation model is self source—lateral expulsion of hydrocarbon—multistage accumulation, or hydrocarbon sourced from and preserved in the same old rocks—long term expulsion of hydrocarbon—multistage accumulation.

  • Jing-tian Tang , Ji-feng Zhang , Bing Feng , Ye Wang

    Three dimensional geophysical models were abstracted and established according to characteristics of oil and gas reservoir. Then direct current fields for different models were simulated with finite element software (finite element program generator) by hole-to-surface resistivity method. Numerical solution was compared with analytical one for the homogeneity earth model. And a new parameter of deviation rate was proposed by analyzing different plot curves. The results show that the relative error of solution for homogeneity earth model may attain to 0.043%. And deviation rate decreases from 18% to 1% and its anomaly range becomes wide gradually when the depth of oil and gas reservoir increases from 200 to 1 500 m. If resistivity ratio of oil and gas reservoir to sur-rounding rock decreases from 100 to 10 for the resistive oil and gas reservoir, the amplitude attenuation of deviation rate nearly reaches 8%. When there exists stratum above oil and gas reservoir, and influence of resistive stratum may be eliminated or weakened and anomaly of oil and gas reservoir can be strengthened.

  • You-wang Zhang , Wei-hua Gui

    Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system, adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty. At the same time, gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort. The results show that the unrealization problem caused by some system’s immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome. On the other hand, the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term’s gain in the GASMVSC make the system possess strong robustness and improved steady accuracy, and the chattering phenomenon of the control effort is also suppressed effectively.

  • Jian-guo Cao , Gang-cheng Wei , Jie Zhang , Xian-lin Chen , Yi-zhong Zhou

    The roll contour pattern and variety of work and backup rolls in service and its effect on profile and flatness control performance in 1 700 mm hot strip mill at Wuhan Iron and Steel (Group) Corporation were tested and analyzed by the developed finite element models of different typical roll contours configurations. A rather smooth local work roll contour near strip edges and an increase in rolled length can be obtained by application of long stroke work roll shifting system with conventional work roll contours that is incapable of the crown control. In comparison with the conventional backup and work roll contours configuration, the crown control range by the roll bending force enhances by 12.79% and the roll gap stiffness increases by 25.26% with the developed asymmetry self-compensating work rolls(ASR) and varying contact backup rolls(VCR). A better strip profile and flatness quality, an increase in coil numbers within the rolling campaign and a significant alleviated effect of severe work roll wear contours on performance of edge drop control are achieved by the application of ASR with crown control and wear control ability in downstream stand F5 and VCR in all stands of 1 700 mm hot strip mill.

  • Mao Li , Jie-ming Zhou

    Various busbar configurations were built and modeled by the custom code based on the commercial package ANSYS for the 500 kA aluminum electrolysis cell. The configuration parameters, such as side riser entry ratio, number of cathode bars connected to each riser, vertical location of side cathode busbar and short side cathode busbar, distance between rows of cells in potline, the number of neighboring cells, ratio of compensation busbar carried passing under cell and its horizontal location under cell along with large magnetohydrodynamic(MHD) computation based on the custom evaluation function were simulated and discussed. The results show that a cell with riser entry y ratio of 11:9:8:9:11 and cathode busbar located at the level of aluminum solution, 50% upstream cathode current passing under cell for magnetic field compensation, the distance between rows of 50 m is more stable.

  • Xiao-li Yang , Zhi-rong Sui

    Seismic failure mechanisms were investigated for soil slopes subjected to strip load with upper bound method of limit analysis and finite difference method of numerical simulation, considering the influence of associated and nonassociated flow rules. Quasi-static representation of soil inertia effects using a seismic coefficient concept was adopted for seismic failure analysis. Numerical study was conducted to investigate the influences of dilative angle and earthquake on the seismic failure mechanisms for the loaded slope, and the failure mechanisms for different dilation angles were compared. The results show that dilation angle has influences on the seismic failure surfaces, that seismic maximum displacement vector decreases as the dilation angle increases, and that seismic maximum shear strain rate decreases as the dilation angle increases.

  • Ping Yang , Zhen-bin Peng , Yi-qun Tang , Wen-xiang Peng , Zhong-ming He

    To study the relationship between grouting effect and grouting factors, three factors (seven parameters) directionless pressure and small cycle grouting model experiment on sandy gravel was done, which was designed according to uniform design method. And regressing was applied to analysis of the test data. The two models test results indicate that when the diffusing radius of grout changes from 26 to 51 cm, the grouted sandy gravel compressing strength changes from 2.13 to 12.30 MPa; the relationship between diffusing radius(R) and water cement ratio(m), permeability coefficient(k), grouting pressure(p), grouting time(t) is R=19.953m0.121k0.429p0.412t0.437; the relationship between compressing strength(P) and porosity(n), water cement ratio, grouting pressure, grouting time is P=0.984n0.517m−1.488p0.118t0.031. So the porosity of sandy gravel, the permeability coefficient of sandy gravel, grouting pressure, grouting time, water cement ratio are main factors to influence the grouting effect. The grouting pressure is the main factor to influence grouting diffusing radius, and the water cement ratio is the main factor to influence grouted sandy gravel compressing strength.

  • Xi-ling Liu , Xi-bing Li , Fa-ben Li , Guo-yan Zhao , Yu-hui Qin

    Ground constructions and mines are severely threatened by underground cavities especially those unsafe or inaccessible ones. Safe and precise cavity detection is vital for reasonable cavity evaluation and disposal. The conventional cavity detection methods and their limitation were analyzed. Those methods cannot form 3D model of underground cavity which is used for instructing the cavity disposal; and their precisions in detection are always greatly affected by the geological circumstance. The importance of 3D cavity detection in metal mine for safe exploitation was pointed out; and the 3D cavity laser detection method and its principle were introduced. A cavity auto scanning laser system was recommended to actualize the cavity 3D detection after comparing with the other laser detection systems. Four boreholes were chosen to verify the validity of the cavity auto scanning laser system. The results show that the cavity auto scanning laser system is very suitable for underground 3D cavity detection, especially for those inaccessible ones.