Search2003 Vol. 10, No. 3
Display Method:
2003, vol. 10, no. 3, pp.
1-7.
Abstract:
An overview of extraction of some trace metal ions using molten solvent (low melting substance) during last two decades is presented. The development of this technique since its inception is briefly traced. The comparison of extraction efficiency, thermo-dynamics and kinetics mainly involving extraction of rare earth ions between molten solvent extraction at high temperature and usual liquid-liquid extraction at room temperature are discussed in detail. The various parameters obtained from the previous and presentstudies such as equilibrium extraction constant Kex, pH1/2, the rmodynamic and kinetic data are displayed in tabular form. Finally, thecurrent demands, disadvantages and future prospects are also evaluated.
An overview of extraction of some trace metal ions using molten solvent (low melting substance) during last two decades is presented. The development of this technique since its inception is briefly traced. The comparison of extraction efficiency, thermo-dynamics and kinetics mainly involving extraction of rare earth ions between molten solvent extraction at high temperature and usual liquid-liquid extraction at room temperature are discussed in detail. The various parameters obtained from the previous and presentstudies such as equilibrium extraction constant Kex, pH1/2, the rmodynamic and kinetic data are displayed in tabular form. Finally, thecurrent demands, disadvantages and future prospects are also evaluated.
2003, vol. 10, no. 3, pp.
8-12.
Abstract:
Trace elements including REE (Rare Earth Elements) in fluid inclusions in lherzolite, olivine, orthopyroxene, and clinopy-roxene have been determined by heating-decrepitation and ICP-MS (Element Type Inductively Coupled Plasma-Mass Spectrometry)method. Normalized CO2 fluid/chondrite data show that mantle fluids are rich in REEs, especially LREEs (Light Rare Earth Ele-ments), several times or dozen times higher than mantle rocks and mantle mininerals. There are close relationships among the REE data of olivine, orthopyroxene, clinopyroxene and lherzolite. Compared to the data of chemical dissolution method, it is believed that REE data obtained from heating-decrepitation and ICP-MS technique are contributed by CO2 fluid inclusions. About 60% (mass fraction) of tiny inclusions are observed not to be decrepitated above 1000℃, so REE data obtained are only contributed by decrepi-tated inclusions. Mantle fluids rich in LREE play an important role in mantle metasomatism, partial melting and mineralization.
Trace elements including REE (Rare Earth Elements) in fluid inclusions in lherzolite, olivine, orthopyroxene, and clinopy-roxene have been determined by heating-decrepitation and ICP-MS (Element Type Inductively Coupled Plasma-Mass Spectrometry)method. Normalized CO2 fluid/chondrite data show that mantle fluids are rich in REEs, especially LREEs (Light Rare Earth Ele-ments), several times or dozen times higher than mantle rocks and mantle mininerals. There are close relationships among the REE data of olivine, orthopyroxene, clinopyroxene and lherzolite. Compared to the data of chemical dissolution method, it is believed that REE data obtained from heating-decrepitation and ICP-MS technique are contributed by CO2 fluid inclusions. About 60% (mass fraction) of tiny inclusions are observed not to be decrepitated above 1000℃, so REE data obtained are only contributed by decrepi-tated inclusions. Mantle fluids rich in LREE play an important role in mantle metasomatism, partial melting and mineralization.
2003, vol. 10, no. 3, pp.
13-15.
Abstract:
An experiment of a new type full size copper stave for a real blast furnace was carried out in a special-designed experimental system. The 3-D temperature distribution inside the stave including isotherm was obtained based on the experiment data. And the effects of the temperature of cooling water and the velocity of the water as well as the temperature of the furnace on the 3-D ternperature distribution were obtained. The experimental and calculation results show that the highest temperature of the hot surface is lower than 90℃ which is very good for the solidified slag formation on the hot surface and protecting the stave.
An experiment of a new type full size copper stave for a real blast furnace was carried out in a special-designed experimental system. The 3-D temperature distribution inside the stave including isotherm was obtained based on the experiment data. And the effects of the temperature of cooling water and the velocity of the water as well as the temperature of the furnace on the 3-D ternperature distribution were obtained. The experimental and calculation results show that the highest temperature of the hot surface is lower than 90℃ which is very good for the solidified slag formation on the hot surface and protecting the stave.
2003, vol. 10, no. 3, pp.
16-20.
Abstract:
One of the methods forming the shell is to appropriately design the cooling staves and hearth without overheating during the campaign life of the furnace. The three-dimensional steady mathematical models for calculating the temperature distribution in the coolers and two-dimensional unsteady mathematical models with phase-change latent heat for calculating the temperature dis-tribution of the hearth bottom were established. The calculation results show that the formation of the slag-metal protection shell can be achieved by optimizing the design parameters of the coolers. Increasing the heat conductivity of the carbon brick can move the isothermal line of 1150℃ upward outside the hearth bottom.
One of the methods forming the shell is to appropriately design the cooling staves and hearth without overheating during the campaign life of the furnace. The three-dimensional steady mathematical models for calculating the temperature distribution in the coolers and two-dimensional unsteady mathematical models with phase-change latent heat for calculating the temperature dis-tribution of the hearth bottom were established. The calculation results show that the formation of the slag-metal protection shell can be achieved by optimizing the design parameters of the coolers. Increasing the heat conductivity of the carbon brick can move the isothermal line of 1150℃ upward outside the hearth bottom.
2003, vol. 10, no. 3, pp.
21-25.
Abstract:
The performance of the flat jet with an inclination angle was investigated by a water model. A mathematical model for the shrinkage and the trajectory of the flat jet with an inclination angle was derived theoretically and verified by experimental data of the water model. The experimental results indicate that the inclination angle (α) has no influence on the shrinkage of the flat jet, the shrinkage of the flat jet along the width direction decreases with the increasing of the initial velocity at the exit (u0) and the initial thickness of the flat jet (t0). Enough bigger initial exit velocity (u0) and initial thickness can suppress the shrinkage of the flat jet along the width direction and keep the flat jet stabilized. In addition, the trajectory of the flat jet with an inclination angle is parabolic and must be taking into consideration when to determine the striking distance.
The performance of the flat jet with an inclination angle was investigated by a water model. A mathematical model for the shrinkage and the trajectory of the flat jet with an inclination angle was derived theoretically and verified by experimental data of the water model. The experimental results indicate that the inclination angle (α) has no influence on the shrinkage of the flat jet, the shrinkage of the flat jet along the width direction decreases with the increasing of the initial velocity at the exit (u0) and the initial thickness of the flat jet (t0). Enough bigger initial exit velocity (u0) and initial thickness can suppress the shrinkage of the flat jet along the width direction and keep the flat jet stabilized. In addition, the trajectory of the flat jet with an inclination angle is parabolic and must be taking into consideration when to determine the striking distance.
2003, vol. 10, no. 3, pp.
26-29.
Abstract:
The function of disproportionation and desorption stages of hydrogenation-disproportionation-desorption-recombination (HDDR) process in the formation of magnetic anisotropy was studied. The results showed that degree of anisotropy (DOA) of Nd13Fe80B7 induced by appropriate HDDR process is comparable with that of Nd13Fe80-xB7Mx (M=Co, Zr or Ga), however, the moder-ate coercive force of Nd13Fe80B7 magnetic powder led to an undesirable (BH)max of 104 kJ/m3 in bonded magnet. Experiments demonstrated that a relatively short disproportionation time, combined with a high desorption temperature and slow desorption rate, during HDDR process is beneficial to anisotropy attainment, but HDDR Nd13Fe80B7 magnetic powder becomes isotropic if the dispropor-tionation time is longer than a certain period. This phenomenon strongly indicated that the origin of anisotropy in NdFeB-type HDDR material is contributed by disproportionation stage. XRD (X-ray Diffraction) analysis and TEM (Transmission Electron Mi-croscope) observation told that no other phase except NdH2, α-Fe and Fe2B has been found in the disproportionation step. The for-mation of HDDR Nd13Fe80B7 anisotropy might be related to the early lamella disproportionation structure.
The function of disproportionation and desorption stages of hydrogenation-disproportionation-desorption-recombination (HDDR) process in the formation of magnetic anisotropy was studied. The results showed that degree of anisotropy (DOA) of Nd13Fe80B7 induced by appropriate HDDR process is comparable with that of Nd13Fe80-xB7Mx (M=Co, Zr or Ga), however, the moder-ate coercive force of Nd13Fe80B7 magnetic powder led to an undesirable (BH)max of 104 kJ/m3 in bonded magnet. Experiments demonstrated that a relatively short disproportionation time, combined with a high desorption temperature and slow desorption rate, during HDDR process is beneficial to anisotropy attainment, but HDDR Nd13Fe80B7 magnetic powder becomes isotropic if the dispropor-tionation time is longer than a certain period. This phenomenon strongly indicated that the origin of anisotropy in NdFeB-type HDDR material is contributed by disproportionation stage. XRD (X-ray Diffraction) analysis and TEM (Transmission Electron Mi-croscope) observation told that no other phase except NdH2, α-Fe and Fe2B has been found in the disproportionation step. The for-mation of HDDR Nd13Fe80B7 anisotropy might be related to the early lamella disproportionation structure.
2003, vol. 10, no. 3, pp.
30-34.
Abstract:
The dynamic process of non-equilibrium grain boundary segregation of trace boron in Fe-40%Ni alloy during cooling and the effect of cooling rate were investigated by boron tracking autoradiography technique. The results indicate that during cooling process, the amount of segregated boron on grain boundary firstly increases fast, then enters a comparatively even increasing stage and increases rapidly again at the third stage. The details of each stage varied with cooling rate are explained. When thc segregation develops to a certain degree, the segregated boron atoms transform fiom solute status to precipitate status.
The dynamic process of non-equilibrium grain boundary segregation of trace boron in Fe-40%Ni alloy during cooling and the effect of cooling rate were investigated by boron tracking autoradiography technique. The results indicate that during cooling process, the amount of segregated boron on grain boundary firstly increases fast, then enters a comparatively even increasing stage and increases rapidly again at the third stage. The details of each stage varied with cooling rate are explained. When thc segregation develops to a certain degree, the segregated boron atoms transform fiom solute status to precipitate status.
2003, vol. 10, no. 3, pp.
35-38.
Abstract:
In order to obtain a fundamental understanding of the corrosion behavior of tin in atmosphere, in situ IR-RAS (infrared reflection absorption spectroscopy) measurements were performed on tin in humid air containing SO2 and NO2 at room temperature.Time-resolved in situ IR spectra in air of 90% RH (relative humidity) containing 1×10-5-2.2×10-5 SO2 suggested that the tin oxide layers worked as a protective film and no significant corrosion occurred. The conosion products in air of 80%-90% RH containing 1×10-5-2.2×10-5 NO2 were SnO2, SnO, nitrate and hyponitrite. The synergistic effect of SO2 and NO2 on corrosion of tin was not observed in air of 90% RH containing 0.84×10-6 SO2 and 1.8×10-6 NO2.
In order to obtain a fundamental understanding of the corrosion behavior of tin in atmosphere, in situ IR-RAS (infrared reflection absorption spectroscopy) measurements were performed on tin in humid air containing SO2 and NO2 at room temperature.Time-resolved in situ IR spectra in air of 90% RH (relative humidity) containing 1×10-5-2.2×10-5 SO2 suggested that the tin oxide layers worked as a protective film and no significant corrosion occurred. The conosion products in air of 80%-90% RH containing 1×10-5-2.2×10-5 NO2 were SnO2, SnO, nitrate and hyponitrite. The synergistic effect of SO2 and NO2 on corrosion of tin was not observed in air of 90% RH containing 0.84×10-6 SO2 and 1.8×10-6 NO2.
2003, vol. 10, no. 3, pp.
39-42.
Abstract:
Independent microstructures made of Ni metal were fabricated by five sequential processes:porous anodic oxide film for-mation, pore sealing, laser irradiation, Ni electroplating, and removal of the aluminum substrate and anodic oxide films. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type anodic oxide films, and then immersed in boiling dis-tilled water for pore sealing. The anodized and pore-sealed specimens were irradiated with a pulsed neodymium-doped yttrium alu-minum garnet (Nd-YAG) laser beam in a Ni plating solution to remove anodic oxide film locally by rotating and moving up/down with an XYZθ-stage. Nickel was deposited at the area where film had been removed by cathodic polarization in the solution before removing the aluminum substrate and anodic oxide films in NaOH solutions. Cylindrical or plain network structures were fabricated successfully.
Independent microstructures made of Ni metal were fabricated by five sequential processes:porous anodic oxide film for-mation, pore sealing, laser irradiation, Ni electroplating, and removal of the aluminum substrate and anodic oxide films. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type anodic oxide films, and then immersed in boiling dis-tilled water for pore sealing. The anodized and pore-sealed specimens were irradiated with a pulsed neodymium-doped yttrium alu-minum garnet (Nd-YAG) laser beam in a Ni plating solution to remove anodic oxide film locally by rotating and moving up/down with an XYZθ-stage. Nickel was deposited at the area where film had been removed by cathodic polarization in the solution before removing the aluminum substrate and anodic oxide films in NaOH solutions. Cylindrical or plain network structures were fabricated successfully.
2003, vol. 10, no. 3, pp.
43-46.
Abstract:
The frequency of heterogeneous nucleation during the solidification of Al-Si binary alloy was estimated by comparing experimentally obtained macrostructures of castings with numerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooled copper chill in an adiabatic mold. The location of colunmar to equiaxed transition (CET) in the solidified alloy ingot was measured. A numerical simulation for grain structure formation based on the Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloy was evaluated by producing similar structure with the experimental one. The frequency of heterogeneous nucleation was expressed as a probabilistic function with an exponential form of undercooling that deter-mines the probability of nucleation event in the simulation. The value of the exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloy varied with initial Sicontent.
The frequency of heterogeneous nucleation during the solidification of Al-Si binary alloy was estimated by comparing experimentally obtained macrostructures of castings with numerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooled copper chill in an adiabatic mold. The location of colunmar to equiaxed transition (CET) in the solidified alloy ingot was measured. A numerical simulation for grain structure formation based on the Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloy was evaluated by producing similar structure with the experimental one. The frequency of heterogeneous nucleation was expressed as a probabilistic function with an exponential form of undercooling that deter-mines the probability of nucleation event in the simulation. The value of the exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloy varied with initial Sicontent.
2003, vol. 10, no. 3, pp.
47-50.
Abstract:
A part of Al-Ti-Mo-Cr quaternary phase diagram is constructed for the microstructure control of DO22-Al3Ti or its derivative, Ll2-(Al,Cr)3Ti, -based alloys. It was found that quaternary bce phase equilibrates with either DO22-Al3Ti or Ll2-(Al,Cr)3Ti, or both, exist in large compositional areas. The mechanical properties is strongly affected by precipitates appearing, and presumablyalloy microstructures.
A part of Al-Ti-Mo-Cr quaternary phase diagram is constructed for the microstructure control of DO22-Al3Ti or its derivative, Ll2-(Al,Cr)3Ti, -based alloys. It was found that quaternary bce phase equilibrates with either DO22-Al3Ti or Ll2-(Al,Cr)3Ti, or both, exist in large compositional areas. The mechanical properties is strongly affected by precipitates appearing, and presumablyalloy microstructures.
2003, vol. 10, no. 3, pp.
51-54.
Abstract:
The temperature field of FGH95 alloy droplet atomized by plasma rotating electrode processing (PREP) during solidification has been calculated through numerical analysis based on equivalent sensible heat capacity method. And thus the relational culves among temperature gradient of solid-liquid interface, moving velocity of solid-liquid interface and solid fraction during solidification have been presented. The results indicate that the relation between average temperature gradient of solid-liquid interface and droplet size, and the relation between average moving velocity of solid-liquid interface and droplet size can be expressed during solidification.
The temperature field of FGH95 alloy droplet atomized by plasma rotating electrode processing (PREP) during solidification has been calculated through numerical analysis based on equivalent sensible heat capacity method. And thus the relational culves among temperature gradient of solid-liquid interface, moving velocity of solid-liquid interface and solid fraction during solidification have been presented. The results indicate that the relation between average temperature gradient of solid-liquid interface and droplet size, and the relation between average moving velocity of solid-liquid interface and droplet size can be expressed during solidification.
2003, vol. 10, no. 3, pp.
55-61.
Abstract:
In order to further understand the similarity and difference between deformation mechanisms of single crystals and polycrystalline materials, the influence of external constraint and rolling geometry on the deformation behaviour of copper single crystals with {123}<634> orientation was investigated by embedding them into metal frames of different strengths. The metal frames were made of aluminum and mild steel, respectively. The results show that the deformation banding degree of the crystal increases with the strength of metal frame and shear strain. For the crystals rolled under lower γg (γg is the ratio of the geometrical redundant shear strain to the normal rolling strain), the deformation is homogeneous. For the crystals rolled under higher γg, the deformation is extremely inhomogeneous. The deformation is more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. The S-orientation is more stable in the crystals rolled under lower γg than that rolled under higher γg.
In order to further understand the similarity and difference between deformation mechanisms of single crystals and polycrystalline materials, the influence of external constraint and rolling geometry on the deformation behaviour of copper single crystals with {123}<634> orientation was investigated by embedding them into metal frames of different strengths. The metal frames were made of aluminum and mild steel, respectively. The results show that the deformation banding degree of the crystal increases with the strength of metal frame and shear strain. For the crystals rolled under lower γg (γg is the ratio of the geometrical redundant shear strain to the normal rolling strain), the deformation is homogeneous. For the crystals rolled under higher γg, the deformation is extremely inhomogeneous. The deformation is more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. The S-orientation is more stable in the crystals rolled under lower γg than that rolled under higher γg.
2003, vol. 10, no. 3, pp.
62-65.
Abstract:
The fixed points in logistic mapping digital-flow chaos strange attractor are studied in detail. When k=n in logistic equation, there exist no more than 2n fixed points, which are deduced and proved theoretically. Three corollaries about the fixed points of logistic mapping are proposed and proved respectively. These theoretn and corollaries provide a theoretical basis for choosing parameter of chaotic sequences in chaotic secure communication and chaotic digital watermarking. And they are testified by simulation.
The fixed points in logistic mapping digital-flow chaos strange attractor are studied in detail. When k=n in logistic equation, there exist no more than 2n fixed points, which are deduced and proved theoretically. Three corollaries about the fixed points of logistic mapping are proposed and proved respectively. These theoretn and corollaries provide a theoretical basis for choosing parameter of chaotic sequences in chaotic secure communication and chaotic digital watermarking. And they are testified by simulation.
A rate based congestion control algorithm in networks with coexisting unicast and multicast sessions
2003, vol. 10, no. 3, pp.
66-72.
Abstract:
The optimal rate control problem in networks with unicast and multirate multicast sessions is investigated. A penalty function approach is used to solve a convex program formulation of this problem, and then a heuristic rate control algorithm is derived. The algorithm is distributed, and suitable both for source-driven unicast sessions and receiver-driven multicast sessions. To obtain practical viability, the computational burden on core routers as well as end-hosts is kept very low, also is the overhead of net-work congestion feedback. Simulation results show that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessions coexisting with multirate multicast sessions in a fair and friendly manner. It is also shown that various fairness criteria of resource allocation could be achieved by choosing appropriate utility functions, and resource-utilizing efficiencies would be likewise different.
The optimal rate control problem in networks with unicast and multirate multicast sessions is investigated. A penalty function approach is used to solve a convex program formulation of this problem, and then a heuristic rate control algorithm is derived. The algorithm is distributed, and suitable both for source-driven unicast sessions and receiver-driven multicast sessions. To obtain practical viability, the computational burden on core routers as well as end-hosts is kept very low, also is the overhead of net-work congestion feedback. Simulation results show that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessions coexisting with multirate multicast sessions in a fair and friendly manner. It is also shown that various fairness criteria of resource allocation could be achieved by choosing appropriate utility functions, and resource-utilizing efficiencies would be likewise different.
2003, vol. 10, no. 3, pp.
73-75.
Abstract:
A new cellular neural network (CNN) with nonlinear templates is presented for extracting convex corners of objects in gray-scale images. Application examples showed that the new CNN can even detect convex corner characteristics of objects in im-ages with Gaussian noise.
A new cellular neural network (CNN) with nonlinear templates is presented for extracting convex corners of objects in gray-scale images. Application examples showed that the new CNN can even detect convex corner characteristics of objects in im-ages with Gaussian noise.
2003, vol. 10, no. 3, pp.
76-78.
Abstract:
Transmission electron microscopy (TEM) was applied to investigate the evolution of dislocation configuration and strain induced precipitation behavior during relaxation process after deformation in Fe-Ni-Nb-Ti-C-B alloy. Experimental results indicate that the dislocation density is very high and distribute randomly before relaxation. As the relaxation time increasing, dislocation cell swill form gradually by polygonization. The strain induced precipitation retards the progress. In the final relaxation stage, most dislo-cations get rid of pinning of precipitates and the cells have developed into subgrains with large size.
Transmission electron microscopy (TEM) was applied to investigate the evolution of dislocation configuration and strain induced precipitation behavior during relaxation process after deformation in Fe-Ni-Nb-Ti-C-B alloy. Experimental results indicate that the dislocation density is very high and distribute randomly before relaxation. As the relaxation time increasing, dislocation cell swill form gradually by polygonization. The strain induced precipitation retards the progress. In the final relaxation stage, most dislo-cations get rid of pinning of precipitates and the cells have developed into subgrains with large size.
Submit Manuscript
E-mail alert
RSS
