Search2002 Vol. 9, No. 4
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2002, vol. 9, no. 4, pp.
241-244.
Abstract:
The feasibility for modifying the wettability and floatability of sulfide minerals by electron beam irradiation has been studied experimentally. The wettability of crystalline pyrite and floatability of some sulfide as pyrite, arsenopyrite, chalcopyrite and marmatite after irradiation were examined by flotation in a modified Hallimond tube. Experimental results show that the hydrophobicity of crystalline pyrite enhances with the increase of irradiation dose in a low dose range. And the flotation responses of sulfide minerals on irradiation dosevary with the mineral species and particle size. The floatability of minerals can be regulated by altering irradiation dose. An explanationfor the mechanism has been suggested based on the principle of radiation chemistry.
The feasibility for modifying the wettability and floatability of sulfide minerals by electron beam irradiation has been studied experimentally. The wettability of crystalline pyrite and floatability of some sulfide as pyrite, arsenopyrite, chalcopyrite and marmatite after irradiation were examined by flotation in a modified Hallimond tube. Experimental results show that the hydrophobicity of crystalline pyrite enhances with the increase of irradiation dose in a low dose range. And the flotation responses of sulfide minerals on irradiation dosevary with the mineral species and particle size. The floatability of minerals can be regulated by altering irradiation dose. An explanationfor the mechanism has been suggested based on the principle of radiation chemistry.
2002, vol. 9, no. 4, pp.
245-248.
Abstract:
Based on the measuring data of underwater blasting vibrationand the regression analysis results of these data, two formulae usually used of blasting vibration velocity were compared. Factors that canaffect blasting vibration and frequency were summarized and analyzed.It is thought that the effect of the number of freedom face and burden direction on blasting vibration should be considered during blastingdesign. Based on the relevant research results and the regression results of these data, a formula to calculate under water blasting frequency was put forward.
Based on the measuring data of underwater blasting vibrationand the regression analysis results of these data, two formulae usually used of blasting vibration velocity were compared. Factors that canaffect blasting vibration and frequency were summarized and analyzed.It is thought that the effect of the number of freedom face and burden direction on blasting vibration should be considered during blastingdesign. Based on the relevant research results and the regression results of these data, a formula to calculate under water blasting frequency was put forward.
2002, vol. 9, no. 4, pp.
249-252.
Abstract:
The effects of several collectors and their dosage on pure ilmenorutile at different pH values were studied and the collecting strength of several representative collectors was investigated. The experimental results indicate that diphosphonic acid is a good collector for ilmenorutile and the recovery of ilmenorutile ranges from 90.87% to 91.70% when the pulp pH value is 2.0-4.0 and the dosage is 75mg/L. The sequence of collecting ability for several collectors is as follows:diphosphonic acid > TF279 > cyclic alkyl hydroximic acid > benzyl arsenic acid > salicylic hydroximic acid > alkyl hydroximic acid. Meanwhile, IAS (infrared absorption spectrum) and XPS (X-ray photoelectron spectroscopy) were used to detect and analyze the action mechanism of diphosphonic acid on ilmenorutile. IAS results showed that the characteristic absorption peak relating to P=O as well as P-O vibration occurred between wave numeber 1 140 and 1 032cm^-1, and diphosphonic acid had adsorbed on the surface of ilmenorutile. XPS results indicated that the binding energy of P2P peak of ilmenorutile had changed 0.45 eV after treated by diphosphonic acid. This proves that the adsorption is mainly chemical adsorption.
The effects of several collectors and their dosage on pure ilmenorutile at different pH values were studied and the collecting strength of several representative collectors was investigated. The experimental results indicate that diphosphonic acid is a good collector for ilmenorutile and the recovery of ilmenorutile ranges from 90.87% to 91.70% when the pulp pH value is 2.0-4.0 and the dosage is 75mg/L. The sequence of collecting ability for several collectors is as follows:diphosphonic acid > TF279 > cyclic alkyl hydroximic acid > benzyl arsenic acid > salicylic hydroximic acid > alkyl hydroximic acid. Meanwhile, IAS (infrared absorption spectrum) and XPS (X-ray photoelectron spectroscopy) were used to detect and analyze the action mechanism of diphosphonic acid on ilmenorutile. IAS results showed that the characteristic absorption peak relating to P=O as well as P-O vibration occurred between wave numeber 1 140 and 1 032cm^-1, and diphosphonic acid had adsorbed on the surface of ilmenorutile. XPS results indicated that the binding energy of P2P peak of ilmenorutile had changed 0.45 eV after treated by diphosphonic acid. This proves that the adsorption is mainly chemical adsorption.
2002, vol. 9, no. 4, pp.
253-257.
Abstract:
The mold-filling ability of the semisolid alloy has very important effects on the quality and properties of the work pieces produced by the semisolid forming process. The factorial experiments show that all of the heating factors, such as mold temperature, heating temperature and the keeping time of billets, have some effects on the mold-filling ability of semisolid alloy. According to the analysis of influencing extent on the filling ability, it is found that the most important one of the factors is the mold temperature instead of the billets temperature, the next one is the heating temperature of the billet, and the keeping time rows on the third. It is also found that there is an interrelation between the billet heating temperature and the mold temperature. The effect of the interrelation on the mold-filling abilityis even stronger than the keeping time. The higher the mold temperature, heating temperature or the keeping time is, the better the mold-filling ability of the semisolid alloy is. The parameter to describe themold-filling ability, defined as the maximum filling height along theupright direction or the maximum filling length along the horizontal direction, can be theoretically determined according to the flowing theory of viscous fluid.
The mold-filling ability of the semisolid alloy has very important effects on the quality and properties of the work pieces produced by the semisolid forming process. The factorial experiments show that all of the heating factors, such as mold temperature, heating temperature and the keeping time of billets, have some effects on the mold-filling ability of semisolid alloy. According to the analysis of influencing extent on the filling ability, it is found that the most important one of the factors is the mold temperature instead of the billets temperature, the next one is the heating temperature of the billet, and the keeping time rows on the third. It is also found that there is an interrelation between the billet heating temperature and the mold temperature. The effect of the interrelation on the mold-filling abilityis even stronger than the keeping time. The higher the mold temperature, heating temperature or the keeping time is, the better the mold-filling ability of the semisolid alloy is. The parameter to describe themold-filling ability, defined as the maximum filling height along theupright direction or the maximum filling length along the horizontal direction, can be theoretically determined according to the flowing theory of viscous fluid.
2002, vol. 9, no. 4, pp.
258-261.
Abstract:
Much attention has been paid to copper staves because they have excellent performance and longevity. The hot test of copper staveswas carried out using all-scale stave experiment system and accordingto the results, the temperature distribution and heat characteristicswere studied. The result shows that copper stave possesses outstanding heat transfer ability, a well-distributed temperature field and low temperature on the hot side. In addition, a model was established to calculate the cooling water channels' inner face temperature. The calculation results indicates that the highest temperature of the inner wall of the channels is 42℃, and at the same time, the cold side of the stave temperature is 42-43℃. That is to say, the temperature in the stave is quite uniform.
Much attention has been paid to copper staves because they have excellent performance and longevity. The hot test of copper staveswas carried out using all-scale stave experiment system and accordingto the results, the temperature distribution and heat characteristicswere studied. The result shows that copper stave possesses outstanding heat transfer ability, a well-distributed temperature field and low temperature on the hot side. In addition, a model was established to calculate the cooling water channels' inner face temperature. The calculation results indicates that the highest temperature of the inner wall of the channels is 42℃, and at the same time, the cold side of the stave temperature is 42-43℃. That is to say, the temperature in the stave is quite uniform.
2002, vol. 9, no. 4, pp.
262-264.
Abstract:
Flow structure and heat transfer characteristics of an axisymmetric circular jet impinging on a hot 1Cr18Ni9Ti medium plate have been simulated numerically using computational fluid dynamic (CFD) code. The relation between flow field of jet impingement and its heat transfer capability is analyzed, and the phenomenon that heat transfer at stagnation point is smaller than that of points directly around is discussed. The simulation result provides boundary conditions for thermalanalysis of medium plate quenching.
Flow structure and heat transfer characteristics of an axisymmetric circular jet impinging on a hot 1Cr18Ni9Ti medium plate have been simulated numerically using computational fluid dynamic (CFD) code. The relation between flow field of jet impingement and its heat transfer capability is analyzed, and the phenomenon that heat transfer at stagnation point is smaller than that of points directly around is discussed. The simulation result provides boundary conditions for thermalanalysis of medium plate quenching.
2002, vol. 9, no. 4, pp.
265-268.
Abstract:
The microstructures of copper liners of shaped charges prepared by electroforming technique were investigated by transmission electron microscopy (TEM). Meanwhile, the orientations distributing of thegrains in the electroformed copper liners of shaped charges was examined by the electron backscattering Kikuchi pattern (EBSP) technique. TEM observations have revealed that these electroformed copper liners of shaped charges have the grain size of about 1-3μm and the grains have a preferential orientation distribution along the growth direction.EBSP analysis has demonstrated that the as-formed copper liners of shaped charges exhibit a micro-texture, i.e. one type of fiber texture, and the preferred growth direction is normal to the surface of the liners.
The microstructures of copper liners of shaped charges prepared by electroforming technique were investigated by transmission electron microscopy (TEM). Meanwhile, the orientations distributing of thegrains in the electroformed copper liners of shaped charges was examined by the electron backscattering Kikuchi pattern (EBSP) technique. TEM observations have revealed that these electroformed copper liners of shaped charges have the grain size of about 1-3μm and the grains have a preferential orientation distribution along the growth direction.EBSP analysis has demonstrated that the as-formed copper liners of shaped charges exhibit a micro-texture, i.e. one type of fiber texture, and the preferred growth direction is normal to the surface of the liners.
2002, vol. 9, no. 4, pp.
269-272.
Abstract:
The electrochemical properties and structure of MINi5-xSnx(x=0-0.5) hydrogen storage alloys were investigated by pressure-composition isotherms, electrochemical measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and atomic parameters. With a small amount of tin substitution, the cycle life increases by 52% (0.5C) and 42% (1.0C), but maximum discharge capacity decreases only by 3.0% and 3.5%, respectively. The cycle life is obviously improved by the low vo!ume expansion and the formed SnO2 surface layers upon electrochemical cycling. The substitution of Ni by Sn leads to an increase of the unit cell volume and charge-discharge cycle life and decrease of the plateau pressure, hysteresis and the hydrogen storage capacity. The standard enthalpy of hydride formation decreases with increasing tin substitution. The main factor that influences the standard enthalpy of the hydriding reaction is the number of the outer orbit electrons and not the atomic size factor.
The electrochemical properties and structure of MINi5-xSnx(x=0-0.5) hydrogen storage alloys were investigated by pressure-composition isotherms, electrochemical measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and atomic parameters. With a small amount of tin substitution, the cycle life increases by 52% (0.5C) and 42% (1.0C), but maximum discharge capacity decreases only by 3.0% and 3.5%, respectively. The cycle life is obviously improved by the low vo!ume expansion and the formed SnO2 surface layers upon electrochemical cycling. The substitution of Ni by Sn leads to an increase of the unit cell volume and charge-discharge cycle life and decrease of the plateau pressure, hysteresis and the hydrogen storage capacity. The standard enthalpy of hydride formation decreases with increasing tin substitution. The main factor that influences the standard enthalpy of the hydriding reaction is the number of the outer orbit electrons and not the atomic size factor.
2002, vol. 9, no. 4, pp.
273-276.
Abstract:
The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of thermo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results showthat the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process.The great deformation can achieve completely in view of low flow stress of semi-solid slurry.
The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of thermo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results showthat the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process.The great deformation can achieve completely in view of low flow stress of semi-solid slurry.
2002, vol. 9, no. 4, pp.
277-281.
Abstract:
The fabrication and characterization of new type Nickel oxide/KOH/Active carbon super-capacitor have been described. Porous nickeloxide was prepared by hydrolysis of nickel acetate and heated in air at 300℃. The resulting nickel oxide behaved as an electrochemical capacitor electrode with a specific capacitance (50-70F/g) superior to most active carbon electrodes. This kind of nickel oxide maintained highutilization at high rate of discharge (i.e., high power density) and had excellent cycle life more than 1000 times, while the capacitance of the cell composed of two identical nickel oxide electrodes was poor at high discharge current density and the maximum operational voltage of this type capacitor was limited to 0.5V. A new type super-capacitorwas designed in which the nickel oxide and the active carbon were applied to the positive and negative electrodes respectively. The breakdown voltage of this type super-capacitor was improved effectively to 0.8V and excellent characteristic of high power discharge was attained in this way. The Nickel oxide/KOH/Active carbon super-capacitor has promising potentials in portable telecommunications, uninterruptable power supplies and battery load leveling applications.
The fabrication and characterization of new type Nickel oxide/KOH/Active carbon super-capacitor have been described. Porous nickeloxide was prepared by hydrolysis of nickel acetate and heated in air at 300℃. The resulting nickel oxide behaved as an electrochemical capacitor electrode with a specific capacitance (50-70F/g) superior to most active carbon electrodes. This kind of nickel oxide maintained highutilization at high rate of discharge (i.e., high power density) and had excellent cycle life more than 1000 times, while the capacitance of the cell composed of two identical nickel oxide electrodes was poor at high discharge current density and the maximum operational voltage of this type capacitor was limited to 0.5V. A new type super-capacitorwas designed in which the nickel oxide and the active carbon were applied to the positive and negative electrodes respectively. The breakdown voltage of this type super-capacitor was improved effectively to 0.8V and excellent characteristic of high power discharge was attained in this way. The Nickel oxide/KOH/Active carbon super-capacitor has promising potentials in portable telecommunications, uninterruptable power supplies and battery load leveling applications.
2002, vol. 9, no. 4, pp.
282-286.
Abstract:
The flow behavior of Rene 95 PM alloy was studied from 1050 to 1150℃ with strain rate of 1×10-3, 1×10-2, 1×10-1 and 1s-1. At a given temperature and strain rate, flow curves exhibit a peak followed by flow softening up to a steady state. Moreover, at constant strain, flow stress increases with increasing strain rate and decreasing temperature. An equation relating hyperbolic sine of flow stress to hot working parameters, such as strain, strain rate and temperature, was established by using multiple nonlinear regression method. A very good agreement was found between predicted and experimental flow stress in all the strain range investigated. Application of the constitutive equation in predicting forming loads and flow behavior and temperature distribution in both upper and lower dies in an isothermal forging process of turbine disk of large dimension (about 630mm) by means of a finite element code was systematically analyzed.
The flow behavior of Rene 95 PM alloy was studied from 1050 to 1150℃ with strain rate of 1×10-3, 1×10-2, 1×10-1 and 1s-1. At a given temperature and strain rate, flow curves exhibit a peak followed by flow softening up to a steady state. Moreover, at constant strain, flow stress increases with increasing strain rate and decreasing temperature. An equation relating hyperbolic sine of flow stress to hot working parameters, such as strain, strain rate and temperature, was established by using multiple nonlinear regression method. A very good agreement was found between predicted and experimental flow stress in all the strain range investigated. Application of the constitutive equation in predicting forming loads and flow behavior and temperature distribution in both upper and lower dies in an isothermal forging process of turbine disk of large dimension (about 630mm) by means of a finite element code was systematically analyzed.
2002, vol. 9, no. 4, pp.
287-291.
Abstract:
Thermal mechanical cyclic strain tests were carried out under in-phase and out-of-phase conditions on a Nickel-base Super-alloy GH4133 in the temperature range of 571-823℃. Based on analyzing the present models of TMF (thermal mechanical fatigue) life prediction, a new model for predicting nickel-base superalloy TMF lifetime was proposed. TMF life of superalloy GH4133 was calculated accurately based on the new model. Experimental TMF life has been compared with the calculated results and all results fall in the scatter band of 1.5. The calculating results show that the new model is not only simple, but also precise. This model will play great roles in life prediction of the metal materials and the engineering components subjected to non-isothermal service conditions.
Thermal mechanical cyclic strain tests were carried out under in-phase and out-of-phase conditions on a Nickel-base Super-alloy GH4133 in the temperature range of 571-823℃. Based on analyzing the present models of TMF (thermal mechanical fatigue) life prediction, a new model for predicting nickel-base superalloy TMF lifetime was proposed. TMF life of superalloy GH4133 was calculated accurately based on the new model. Experimental TMF life has been compared with the calculated results and all results fall in the scatter band of 1.5. The calculating results show that the new model is not only simple, but also precise. This model will play great roles in life prediction of the metal materials and the engineering components subjected to non-isothermal service conditions.
2002, vol. 9, no. 4, pp.
292-297.
Abstract:
Fe-Cr-Mn(W, V) austenite steels used as low radioactive structural materials in fusion reactor have been investigated. The resultsshow that the high temperature strength and the creep fracture life of Fe-Cr-Mn(W, V) steels can be effectively improved through (C+N) complex-strengthening, so can be the high temperature ductility. The strength and ductility of the steels are superior to that of SUS316 steels and JPCAS below 673K. The relationship between strength, ductility andthe formation temperature is related to the evolution of deformation microstructure. The fracture and microstructure observation above 673Kindicates that the main way to further improve ductility at high temperature is the control of carbide coarsening at the grain boundaries.
Fe-Cr-Mn(W, V) austenite steels used as low radioactive structural materials in fusion reactor have been investigated. The resultsshow that the high temperature strength and the creep fracture life of Fe-Cr-Mn(W, V) steels can be effectively improved through (C+N) complex-strengthening, so can be the high temperature ductility. The strength and ductility of the steels are superior to that of SUS316 steels and JPCAS below 673K. The relationship between strength, ductility andthe formation temperature is related to the evolution of deformation microstructure. The fracture and microstructure observation above 673Kindicates that the main way to further improve ductility at high temperature is the control of carbide coarsening at the grain boundaries.
2002, vol. 9, no. 4, pp.
298-301.
Abstract:
The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic ofthe subsurface hardness distribution and the abrasive wear resistanceis related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with thecarbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.
The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic ofthe subsurface hardness distribution and the abrasive wear resistanceis related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with thecarbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.
2002, vol. 9, no. 4, pp.
302-304.
Abstract:
An approach of adaptive predictive control with a new structure and a fast algorithm of neural network (NN) is proposed. NN modeling and optimal predictive control are combined to achieve both accuracy and good control performance. The output of nonlinear network model is adopted as a measured disturbance that is therefore weakened in predictive feed-forward control. Simulation and practical application show the effectiveness of control by the proposed approach.
An approach of adaptive predictive control with a new structure and a fast algorithm of neural network (NN) is proposed. NN modeling and optimal predictive control are combined to achieve both accuracy and good control performance. The output of nonlinear network model is adopted as a measured disturbance that is therefore weakened in predictive feed-forward control. Simulation and practical application show the effectiveness of control by the proposed approach.
2002, vol. 9, no. 4, pp.
305-310.
Abstract:
A linear mass-spring system model of a tractor-semitrailer together with driver body parts and sprung seat is presented. Natural frequencies of the system are calculated and response of components in the system to road roughness is completed by means of computer simulation and power spectral density (PSD) approach in all of road conditions and loading cases. The results show that the severest situation of response of the system occurs when the road in rough condition and vehicle unladen. The most sensitive frequency to human body parts is around 0.9Hz, and model types of a human body seem to be not significant tothe response of a heavy tractor-semitrailer system, including to the response of the driver himself.
A linear mass-spring system model of a tractor-semitrailer together with driver body parts and sprung seat is presented. Natural frequencies of the system are calculated and response of components in the system to road roughness is completed by means of computer simulation and power spectral density (PSD) approach in all of road conditions and loading cases. The results show that the severest situation of response of the system occurs when the road in rough condition and vehicle unladen. The most sensitive frequency to human body parts is around 0.9Hz, and model types of a human body seem to be not significant tothe response of a heavy tractor-semitrailer system, including to the response of the driver himself.
2002, vol. 9, no. 4, pp.
311-318.
Abstract:
The analytic criteria for the local activity theory in one-port cellular neural network (CNN) with five local state variables are presented. The application to a Hyper-chaos synchronization Chua's circuit (HCSCC) CNN with 1125 variables is studied. The bifurcation diagrams of the HCSCC CNN show that they are slightly different from the smoothed CNN with one or two ports and four state variables calculated earlier. The evolution of the patterns of the state variables of the HCSCC CNN is stimulated. Oscillatory patterns, chaotic patterns, convergent or divergent patterns may emerge if the selected cell parameters are located in the locally active domains but nearby or in the edge of chaos domain.
The analytic criteria for the local activity theory in one-port cellular neural network (CNN) with five local state variables are presented. The application to a Hyper-chaos synchronization Chua's circuit (HCSCC) CNN with 1125 variables is studied. The bifurcation diagrams of the HCSCC CNN show that they are slightly different from the smoothed CNN with one or two ports and four state variables calculated earlier. The evolution of the patterns of the state variables of the HCSCC CNN is stimulated. Oscillatory patterns, chaotic patterns, convergent or divergent patterns may emerge if the selected cell parameters are located in the locally active domains but nearby or in the edge of chaos domain.
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