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2004年  第11卷  第4期

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Mineral
Cut slope reinforcement technique in open-pit mines
Yongtao Gao, Jianbo Sun, Shunchuan Wu, Aibing Jin
2004, 11(4): 289-292.
中文摘要(309) PDF(19) SpringerLink
摘要:
The design and practice in supporting the cut slope of an open-pit mine were introduced, in which the high pressure grouting method was used in reinforcing the weak formation in the slopes. Based on a detailed geological survey of the slope, a theoretical analysis was carried out, and the design parameters were proposed, where the Tresca or Mohr-Coulomb yield criteria was employed. A patent technology, named "Technology of high pressure and multiple grouting in different levels within a single hole", was employed in the construction. Anchor bars were also installed as grouting proceeds. This method combines anchoring and grouting comprehensively and was found successful in practice.
Mineral
Mineralogy of clean coal combustion by-products
Ligang Wang, Changhe Chen, Kruse H. Koiker
2004, 11(4): 293-296.
中文摘要(267) PDF(9) SpringerLink
摘要:
Coal combustion technologies are changing in order to bum coal more cleanly. Many "clean combustion" and postcombustion technologies are developed to remove SO2 and NOx gases, particulate matter during combustion, or from the flue gases leaving the furnace. This paper focuses on three types of fly ash (flue gas desulfurization (FGD) residuals, atmospheric fluidized bed combustion (AFBC) residuals and sorbent duct injection (SDI) residuals) which produced by "the clean combustion" and postcombustion technologies. The residuals formed by FGD are PCFA (pulverized coal fly ash) grains entrained with reacted and unreacted sorbent and have lower bulk densities than PCFA grains because it contains higher concentrations of calcium and sulfur, and lower concentrations of silicon, aluminum and iron than PCFAs. AFBC residuals consist of spent bed which is a heterogeneous mixture of coarse-grained bed material and irregularly shaped, unfused, spherical PCFAs. The main crystalline phases in AFBC residuals are anhydrite (reacted sorbent), quartz and lime (unreacted sobent), calcite, hematite, periclase, magnetite and feldspars.The residuals produced by SDI contained 65%-70% PCFA with the larger sizes material being irregularly shaped, fused or roughedged. The reaction products of sorbent (portlandite and lime) included calcium sulfate (anhydrite) and calcium sulfate. The chemical properties of these residuals are similar to those of high calcium PCFAs because of the high alkalinity and high pH of these residuals.
Mineral
Determination of relationships between thermal conductivity and material properties of rocks
Kazim Görgülü
2004, 11(4): 297-301.
中文摘要(322) PDF(23) SpringerLink
摘要:
Energy transfer between the adjacent parts of rocks in underground mines is widely influenced by the thermal conductivity of rocks. The relationships between the thermal conductivity and some material properties of rocks such as the uniaxial compressive strength, unit mass, tensile strength, cohesion, Young's modulus, point load strength, Schmidt rebound hardness, Shore scleroscope hardness and toughness strength were investigated. The statistical analysis of the data obtained in laboratory tests shows that the thermal conductivity increases with increasing the uniaxial compressive strength, unit mass, tensile strength, cohesion, Young's modulus, point load strength, Schmidt rebound hardness and Shore scleroscope hardness, and decreases with increasing the toughness strength.
Metallurgy
Application of soft reduction technique to continuous-casting billets
Mingzhong Liu, Jingshe Li, Shiqi Li, Hongjun Yan, Yingjun Fan, Mingsheng Yang
2004, 11(4): 302-305.
中文摘要(473) PDF(20) SpringerLink
摘要:
Soft reduction technique can decrease the presence of central porosity and centerline segregation, and thus to enhance the internal quality effectively. In order to produce high quality billets, Xinxing Ductile Cast Pipe Group Co. Ltd. of China has installed a set of soft reduction apparatus on No. 1 caster and has achieved a great success. The principle, operating conditions and controlling factors, and the specification of soft reduction for solidifying billets are introduced. In order to make the effectiveness of soft reduction clear, metallurgical evaluation is made. The results indicate that soft reduction can increase equiaxial zone by 3%.
Metallurgy
Pure metal extraction from molten oxide slag by short-circuit galvanic cell
Yunming Gao, Xingmin Guo, Kuochih Chou
2004, 11(4): 306-309.
中文摘要(252) PDF(9) SpringerLink
摘要:
The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]Fe+C saturation|ZrO2(MgO)|(FeO)(siag)|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.
Metallurgy
Modeling study on fluid flow and inclusion motion in 6-strand bloom caster tundishes
Guanghua Wen, Lifeng Zhang, Ping Tang, Zhenjlang Su, Mingmei Zhu, Wuan Gu, Kewen Zhao
2004, 11(4): 310-314.
中文摘要(311) PDF(13) SpringerLink
摘要:
The behavior of fluid flow and particle motion in a 6-strand bloom caster tundish was investigated by a water model and numerical simulation. Compared with a device without flow control, the tundish with flow control has an important effect on the fluid flow pattern and inclusion removal. It is revealed that by non-isothermal process, which is real production condition, the fluid flow in tundish shows a strong buoyancy pattem, which drives particles to move upwards. The particle removal was quantitatively studied by mathematical and physical simulations.
Materials
Low-cost oriented preparation of ultra fine xonotlite fibers
Wen Ni, Shuxiang Chen, Lin Zhu
2004, 11(4): 315-318.
中文摘要(305) PDF(8) SpringerLink
摘要:
Nanometer-sized xonotlite fibers have great potential application in many fields. The traditional method of preparing ultra fine xonotlite fibers uses the ultra fine and highly active silica as the major raw materials, which is not only expensive but also difficult to prepare the xonotlite fibers with diameters around 100 nm. In this study, the ultra fine xonotlite fibers with diameters around 100 nm were prepared by an autoclaving method. The preparation was low-cost oriented by using natural powder quartz and lime as the major raw materials. The intergrowth of the fibers formed thin shell hollow balls or ellipsoids, namely the secondary particles.The length of the nanometer-sized xonotlite fibers was around several microns. The fibers and their secondary particles were produced at 216℃ for 6 h with a continuous stirring of 300-500 r/min. Zirconium oxychloride was used as an additive. The experiments show that zirconium oxychloride has an enormous effect on the growing habit of xonotlite crystals and plays an important role in controlling the diameter of the xonotlite fibers.
Materials
Perpendicular magnetic anisotropy of Co85Cr50/Pt multilayers
Pol Hwang, Baohe Li, Tao Yang, Zhonghai Zhai, Fengwu Zhu
2004, 11(4): 319-323.
中文摘要(261) PDF(11) SpringerLink
摘要:
The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt underlayer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers.When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.
Materials
Tantalum oxide barrier in magnetic tunnel junctions
Guanghua Yu, Tingting Ren, Wei Ji, Jiao Teng, Fengwu Zhu
2004, 11(4): 324-328.
中文摘要(337) PDF(7) SpringerLink
摘要:
Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier.The experimental results show that the chemical state of tantalum is pure Ta5+ and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound,NiTa2. A magnetic "dead layer" could be produced in the NiFe/Ta interface. The "dead layer" is likely to influence the spinning electron transport and the magnetoresistance effect.
Materials
Microstructural characterization and mechanical properties of self-reinforced Si3N4 ceramics containing high oxynitride glass
Xuetao Luo, Lifu Chen, Qianjun Huang, Litong Zhang
2004, 11(4): 329-333.
中文摘要(233) PDF(9) SpringerLink
摘要:
Self-reinforced Si3N4 ceramics containing high oxynitride glass have been fabricated by the control of microstructure evolution and β-Si3N4 grain growth. The effects of the size distribution of the elongated β-Si3N4 grains, and the β-Si3N4 grain growth as well as the oxynitride glass chemical characteristic on the microstructure and mechanical properties were investigated. The experimental results show that the β-Si3N4 grains in high oxynitride glass grow to elongated rod-like crystals and form the stereo-network structure. Under the sintering conditions of 1800℃ and 60 min, a quite uniform microstructure with an average aspect ratio of 6.5 and an average of 1 μm can be obtained. A large amount of oxynitride glass phase with high nitrogen content enhances the elevated temperature fracture toughness because of its high softening temperature and high viscosity. In the present material, the crack deflection and pullout of the elongated rod-like β-Si3N4 grains are the primary toughening mecl anisms.
Materials
Rheologic behavior and PIM processing of WC-TiC-Co powder feedstock
Xuanhui Qu, Jianxiang Gao, Mingli Qin, Changming Lei
2004, 11(4): 334-337.
中文摘要(259) PDF(13) SpringerLink
摘要:
An improved wax-based binder was developed for the powder injection molding (PIM) of WC-TiC-Co cemented carbides.The critical powder loading and the rheologic behavior of the feedstock were determined. It was found that the critical powder loading could achieve up to 62.5% (volume fraction) and the feedstock exhibited a pseudo-plastic flow behavior. The injection molding,debinding and sintering processes were studied. The dimension deviation of the sintered samples could be controlled in the range of ±0.2% with the optimized processing parameters and the mechanical properties were better than or equivalent to those of the same alloy made by conventional press-sintering process.
Materials
Thermo-stability of ultra-fine non-equilibrium microstructures
Huibin Wu, Shanwu Yang, Aimin Guo, Shaoqiang Yuan, Chengjia Shang, Xinlai He
2004, 11(4): 338-342.
中文摘要(166) PDF(9) SpringerLink
摘要:
The evolution of the microstructures and hardness of a bainitic plate steel during tempering at 650℃ has been investigated.The steel was manufactured by RPC (relaxation-precipitation controlling phase transformation) technique. A part of the plate was reheated to 930℃ and held for 1 h before quenched into water (RQ). No obvious change was detected by means of optical microscopy in the RPC steel tempering for 0.5 h, while dislocation cells were formed inside the bainite laths, accompanied by an obvious drop of hardness. The bainite laths started to coalesce in some regions, but the sample hardness kept nearly constant during tempering from 1 to 7 h. With further tempering, polygonal ferrite was formed in local regions while the hardness decreased dramatically. The RQ samples softened faster during tempering and finally transformed into the polygonal ferrite completely. These results indicate that the thermo-stability of fine non-equilibrium microstructures is tightly related to their history.
Materials
3-D thermo-mechanical coupled FEM simulation of continuous hot rolling process of 60SiMnA spring steel bars and rods
Jiahe Ai, Huiju Gao, Tongchun Zhao, Xishan Xie, Yu Liu
2004, 11(4): 343-348.
中文摘要(323) PDF(14) SpringerLink
摘要:
The 3-D thermo-mechanical coupled elasto-plastic finite element method (FEM) was used for the simulation of the twopass continuous hot rolling process of 60SiMnA spring steel bars and rods using MARC/AutoForge3.1 software. The simulated results visualize the metal flow and the dynamic evolutions of the strain, stress and temperature during the continuous hot rolling, especially inside the work-piece. It is shown that the non-uniform distributions of the strain, stress and temperature on the longitudinal and transverse sections are a distinct characteristic of the continuous hot rolling, which can be used as basic data for improving the tool design, predicting and controlling the micro-structural evolution of a bar and rod.
Materials
Processes of depositing platinum on carbon nanotubes and their effect on performance of proton exchange membrane fuel cell
Yanhui Li, Jun Ding, Junfeng Chen, Zongqiang Mao, Cailu Xu, Dehai Wu
2004, 11(4): 349-353.
中文摘要(301) PDF(10) SpringerLink
摘要:
The ultrafine platinum nanoparticles deposited on the surfaces of carbon nanotubes (Pt/CNTs) were prepared by a chemical precipitation method and used as the catalyst of proton exchange membrane fuel cell. The depositing process parameters such as the solution pH value, Pt content and treatment temperature were analyzed. The experimental results show that the optimum process parameters to prepare Pt/CNTs are the solution pH value of 7.0, the theoretical Pt content of 25% (mass fraction) and the heating temperature of 500℃, under the conditions the best performance of the proton exchange membrane fuel cell can be obtained and its voltage can reach 580 mV at a current density of 500 mA/cm2.
Materials
Heat radiative characteristics of ultra-attenuated materials
Dehong Xia, Yonghong Wu
2004, 11(4): 354-358.
中文摘要(197) PDF(7) SpringerLink
摘要:
From the microstructure of heat radiation, the interaction between the incident heat radiative wave and the electromagnetism syntonic wave is analyzed to reveal the emission, absorption, transmission and reflection mechanisms of the incident heat radiative wave in materials. Based on Lorentz dispersion theory, the effect of optical parameters on heat radiative characteristics is also analyzed. The method of ultra-attenuation and nanocrystallization improving the heat radiative characteristics of the material and the emissivity dispersion of the ultra-attenuated materials are brought to light.
Materials
Electrochemical behaviors of novel composite polymer electrolytes for lithium batteries
Guorong Chen, Pengfei Shi, Yongping Bai, Taibing Fan
2004, 11(4): 359-363.
中文摘要(276) PDF(9) SpringerLink
摘要:
A novel composite polymer electrolyte was prepared by blending an appropriate amount of LiClO4 and 10% (mass fraction)fumed SiO2 with the block copolymer of poly (ethylene oxide) (PEO) synthesized by poly (ethylene glycol) (PEG) 400 and CH2Cl2.The ionic conductivity, electrochemical stability, interfacial characteristic and thermal behavior of the composite polymer electrolytewere studied by the measurements of AC impedance spectroscopy, linear sweep voltammetry and differential scanning calorimetry(DSC), respectively. The glass transition temperature acts as a function of salt concentration, which increases with the LiClO4 content.Lewis acid-base model interaction mechanism was introduced to interpret the interactive relation between the filled fumed SiO2 andthe lithium salt in the composite polymer electrolyte. Over the salt concentration range and the measured temperature, the maximumionic conductivity of the composite polymer electrolyte (10-4.41 S/cm) appeared at EO/Li=25 (mole ratio) and 30℃, and the begin-ning oxidative degradation potential versus Li beyond 5 V.
Materials
Microstructure evolution and precipitation behavior of low carbon steel hot strips produced by CSP
Yonglin Kang, Kelu Wang, Hao Yu, Jie Fu, Delu Liu, Zhongbing Wang, Xuewen Chen
2004, 11(4): 364-367.
中文摘要(420) PDF(11) SpringerLink
摘要:
The microstructures of low carbon steel before, during and after rolling deformation of each stand were observed using optical microscope. The result showed that the microstructures were very fine after six passes rolling deformation. The effect of the first stand reduction on microstructure refinement was very distinct. During the rolling process, with the increase of the accumulated strain, the microstructures would further refine, and the density of dislocation would increase at the same time. In continuous casting thin slabs and each finishing stand, lots of observed precipitates were mainly Al2O3 and MnS along the grain boundaries or in grains, which played an important role in the mechanical properties of the hot strips of low carbon steel produced by CSP (compact strip production) technology.
Materials
Lubrication in strip cold rolling process
Jianlin Sun, Yonglin Kang, Tianguo Xiao, Jianze Wang
2004, 11(4): 368-372.
中文摘要(369) PDF(28) SpringerLink
摘要:
A lubrication model was developed for explaining how to form an oil film in the deformation zone, predicting the film thickness and determining the characteristics of lubrication in the strip rolling process, combined with the knowledge of hydrodynamic lubrication and rolling theorievS. Various mineral oils with viscosities from 0.032 to 1.6 Pa·s were used to obtain different film thicknesses in the strip cold rolling. Results from the experiment and calculation show that the oil film forming in hydrodynamic lubrication is up to the bit angle and a higher rolling speed or a higher rolling oil viscosity. The mechanism of mechanical entrainment always affects ihe film thickness lhat increases with the rolling oil viscosity increasing or the reduction rate decreasing in rolling.
Materials
Experiment research on grain drying process in the heat pump assisted fluidized beds
Jing Yang, Li Wang, Fi Xiang, Lige Tong, Hua Su
2004, 11(4): 373-377.
中文摘要(298) PDF(12) SpringerLink
摘要:
A heat pump assisted fluidized bed grain drying experimental system was developed. Based on this system, a serial of experiments was performed under four kinds of air cycle conditions. According to the experimental analysis, an appropriate drying medium-air cycle for the heat pump assisted fluidized bed drying equipment was decided, which is different from the commonly used heat pump assisted drying system. The experimental results concerning the drying operation performance of the new system show that the averaged coefficient of performance (COP) can reach more than 2.5. The economical evaluation was performed and the power consumption for removing a kilogram water from grains was about 0.485 kW·h/kg (H2O), which shows its reasonable commercial efficiency and great application potentiality in future market.
Automation
Arc deflection model and arc direction control for DC arc furnace
Liping Wei, Huang Zhou, Huade Li, Yuanhang Zhou
2004, 11(4): 378-382.
中文摘要(274) PDF(25) SpringerLink
摘要:
Based on the analysis of three-dimensional power conductor for DC arc furnace, the electric arc deflection model was set up and the control system of the arc direction was configured. According to the bus bar distribution at the bottom electrodes cooled by water, the arc direction control principle and its configuration were described. The simulation results show that the control system can restrain the electric arc deflection and control the arc direction.

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