Search2003 Vol. 10, No. 5
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2003, vol. 10, no. 5, pp.
1-8.
Abstract:
Interface reaction (IR) is a frequently observed phenomenon in the study of advanced thin film materials. It is very important to study the reaction conditions at which IR happens and then to suppress or make use of it, the necessary conditions, including both thermodynamical and dynamical conditions of IR were discussed in detail. IRs in various systems, including oxide/silicon,oxide/metal, metal/metal, metal/semiconductor and semiconductor/semiconductor, were reviewed. Methods to suppress and make use of IR were also introduced.
Interface reaction (IR) is a frequently observed phenomenon in the study of advanced thin film materials. It is very important to study the reaction conditions at which IR happens and then to suppress or make use of it, the necessary conditions, including both thermodynamical and dynamical conditions of IR were discussed in detail. IRs in various systems, including oxide/silicon,oxide/metal, metal/metal, metal/semiconductor and semiconductor/semiconductor, were reviewed. Methods to suppress and make use of IR were also introduced.
2003, vol. 10, no. 5, pp.
9-14.
Abstract:
A new hydrometallurgical process for the refractory gold arsenosulfide concentrates under normal temperature and pressure was presented. The experimental results of a refractory gold concentrate show that the total consumption of NaOH in alkaline leaching is only 40% of those theoretically calculated under the conditions of full oxidization at the same oxidation of arsenic to arsenate and sulfur to sulfate. After alkaline leaching, cyanidation and adsorption were carried out for 24 h. The dissolution of gold by NaCN is increased to 95.3% from 12.8% before pretreatment, and meanwhile 99.3% of the adsorption of gold by activated charcoal.The consumption of NaCN for one ton ore is 10 kg, which is 1.2 times less than that before pretreatment. As it is carried out under normal temperature and pressure, the investment of installations is also decreased.
A new hydrometallurgical process for the refractory gold arsenosulfide concentrates under normal temperature and pressure was presented. The experimental results of a refractory gold concentrate show that the total consumption of NaOH in alkaline leaching is only 40% of those theoretically calculated under the conditions of full oxidization at the same oxidation of arsenic to arsenate and sulfur to sulfate. After alkaline leaching, cyanidation and adsorption were carried out for 24 h. The dissolution of gold by NaCN is increased to 95.3% from 12.8% before pretreatment, and meanwhile 99.3% of the adsorption of gold by activated charcoal.The consumption of NaCN for one ton ore is 10 kg, which is 1.2 times less than that before pretreatment. As it is carried out under normal temperature and pressure, the investment of installations is also decreased.
2003, vol. 10, no. 5, pp.
15-19.
Abstract:
In order to study the effect of fused spinel on the properties of phosphoric acid bonded high alumina castables, samples with different contents of fused spinel were prepared. The results show that when the contents of the fused spinel are between 8% and 16% (mass fraction), the castables have good properties. The castables overcome the shortages of the phosphoric acid bonded high alumina castables with bauxite cement as a hardening promoter. The experiments demonstrate that most of the service properties of the castables with fused spinel are better than those of the normal phosphoric acid bonded castables which use bauxite cement as a hardening promoter. The examination of the materials indicates that free MgO inclusions in the spinel powder can promote the hardening of the castables.
In order to study the effect of fused spinel on the properties of phosphoric acid bonded high alumina castables, samples with different contents of fused spinel were prepared. The results show that when the contents of the fused spinel are between 8% and 16% (mass fraction), the castables have good properties. The castables overcome the shortages of the phosphoric acid bonded high alumina castables with bauxite cement as a hardening promoter. The experiments demonstrate that most of the service properties of the castables with fused spinel are better than those of the normal phosphoric acid bonded castables which use bauxite cement as a hardening promoter. The examination of the materials indicates that free MgO inclusions in the spinel powder can promote the hardening of the castables.
2003, vol. 10, no. 5, pp.
20-23.
Abstract:
A general numerical simulating program for three-dimensional (3-D) and time-dependent fluid flow for a reheating furnace with multi-swirling-burners has been developed based upon an arbitrary Lagrangian-Eulerian scheme (ALE) with the finite volume method. The parameters of fluid flow in a reheating furnace with multi-swirling-burners was calculated and the 3-D velocity distributions were obtained. The design of the burners was optimized for forming better swirling flow. The simulation shows that the fluid flow in the reheating furnace with the optimized burners is reasonable.
A general numerical simulating program for three-dimensional (3-D) and time-dependent fluid flow for a reheating furnace with multi-swirling-burners has been developed based upon an arbitrary Lagrangian-Eulerian scheme (ALE) with the finite volume method. The parameters of fluid flow in a reheating furnace with multi-swirling-burners was calculated and the 3-D velocity distributions were obtained. The design of the burners was optimized for forming better swirling flow. The simulation shows that the fluid flow in the reheating furnace with the optimized burners is reasonable.
2003, vol. 10, no. 5, pp.
24-26.
Abstract:
With the help of solidification kinetics, precipitation and growth of TiN have been studied theoretically and the effect of cooling rate on the growth of TiN has been discussed. Through induction electric furnace experiment and electroslag remelting experiment with different cooling rates, the distribution and particle size of TiN were investigated. It is proved that the higher cooling rate is, the smaller the final size of TiN is and the more TiN particles can be found in the steel. That TiN can restrain the growth of columar crystal and enhance the proportion of equiaxed crystals to refine solidification structure as the heterogeneous nucleation sites of 5-ferrite is confirmed preliminarily. A new method to reduce macrosegregation in continuous cast steel is provided.
With the help of solidification kinetics, precipitation and growth of TiN have been studied theoretically and the effect of cooling rate on the growth of TiN has been discussed. Through induction electric furnace experiment and electroslag remelting experiment with different cooling rates, the distribution and particle size of TiN were investigated. It is proved that the higher cooling rate is, the smaller the final size of TiN is and the more TiN particles can be found in the steel. That TiN can restrain the growth of columar crystal and enhance the proportion of equiaxed crystals to refine solidification structure as the heterogeneous nucleation sites of 5-ferrite is confirmed preliminarily. A new method to reduce macrosegregation in continuous cast steel is provided.
2003, vol. 10, no. 5, pp.
27-30.
Abstract:
The effect of[S] on strength and toughness of low alloy steel plates in which sum of[P],[N], T[O] is less than 8×10-5 and the effect of T[O] on strength and toughness of the steel plates in which sum of[S],[P],[N] is less than 7×10-5 were investigated. It is found that the strength of the steel plates decreases with increasing[S] content when[S] is less than 4×10-5. When[S] varies within the range of 4×10-5-1.2×10-4,[S] has no significant effect on strength of the steel. The strength of the steel plates increases with increasing T[O] content when T[O] is less than 30×10-6, but decreases with increasing T[O] when T[O] is more than 3×10-5.The difference between the LETT in plate length direction and LETT in width direction decreases with decreasing[S] content. However, even when[S] is decreased to 9×10-6, the difference of the LETT is still 16℃. When T[O] varies between 1.8×10-5 and 5.2×10-5, the low temperature impact toughness of the steel plates slowly decreases with T[O] increasing. When T[O] increases to more than 5.2×10-5, the low temperature toughness of the steel rapidly decreases with increasing T[O] content.
The effect of[S] on strength and toughness of low alloy steel plates in which sum of[P],[N], T[O] is less than 8×10-5 and the effect of T[O] on strength and toughness of the steel plates in which sum of[S],[P],[N] is less than 7×10-5 were investigated. It is found that the strength of the steel plates decreases with increasing[S] content when[S] is less than 4×10-5. When[S] varies within the range of 4×10-5-1.2×10-4,[S] has no significant effect on strength of the steel. The strength of the steel plates increases with increasing T[O] content when T[O] is less than 30×10-6, but decreases with increasing T[O] when T[O] is more than 3×10-5.The difference between the LETT in plate length direction and LETT in width direction decreases with decreasing[S] content. However, even when[S] is decreased to 9×10-6, the difference of the LETT is still 16℃. When T[O] varies between 1.8×10-5 and 5.2×10-5, the low temperature impact toughness of the steel plates slowly decreases with T[O] increasing. When T[O] increases to more than 5.2×10-5, the low temperature toughness of the steel rapidly decreases with increasing T[O] content.
2003, vol. 10, no. 5, pp.
31-34.
Abstract:
It is clarified that the important method to improve the blast temperature of the small and the middle blast furnaces whose production is about two-thirds of total sum of China from 1000℃ to 1250-1300℃ is to preheat both their combustion-supporting air and coal gas. The air temperature of blast furnaces can be reached to 1250-1300℃ by burning single blast furnace coal gas if high speed burner is applied to blast furnaces and new-type external combustion swirl-flowing hot stove is used to preheat their combustion-supporting air. The computational results of the flow and heat transfer processions in the bot stove prove that the surface of the bed of the thernal storage balls there have not eccentric flow and the flow field and temperature field distribution is even. The computational results of the blast temperature distribution are similar to those determination experiment data. The numerical results also provide references for developing and designing the new-type external combustion swirl-flowing hot stoves.
It is clarified that the important method to improve the blast temperature of the small and the middle blast furnaces whose production is about two-thirds of total sum of China from 1000℃ to 1250-1300℃ is to preheat both their combustion-supporting air and coal gas. The air temperature of blast furnaces can be reached to 1250-1300℃ by burning single blast furnace coal gas if high speed burner is applied to blast furnaces and new-type external combustion swirl-flowing hot stove is used to preheat their combustion-supporting air. The computational results of the flow and heat transfer processions in the bot stove prove that the surface of the bed of the thernal storage balls there have not eccentric flow and the flow field and temperature field distribution is even. The computational results of the blast temperature distribution are similar to those determination experiment data. The numerical results also provide references for developing and designing the new-type external combustion swirl-flowing hot stoves.
2003, vol. 10, no. 5, pp.
35-38.
Abstract:
W-Mo composites with different mass fractions of W and Mo were prepared at 1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of the samples were accurately measured using the ultrasonic pulse echo overlap method, and the wave impedance values of the samples were then calculated. The results show that W-Mo system composites are of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture model was adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimental data demonstrate that the suggested model is sufficiently accurate to predict the wave impedance of W-Mo composites.
W-Mo composites with different mass fractions of W and Mo were prepared at 1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of the samples were accurately measured using the ultrasonic pulse echo overlap method, and the wave impedance values of the samples were then calculated. The results show that W-Mo system composites are of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture model was adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimental data demonstrate that the suggested model is sufficiently accurate to predict the wave impedance of W-Mo composites.
2003, vol. 10, no. 5, pp.
39-43.
Abstract:
In order to obtain thermoelectric materials with high figure of merit, the concept of Hollow (Vacuum) Quantum Structure or Effect and related thermoelectric materials design were proposed. To demonstrate the theory, the materials of (Bi0.15Sb0.85)2Te3 with porous structure have been fabricated. Their thermoelectric properties and the microstructure were investigated and compared with their density structure. It was found that the porous structure could improve their properties greatly.
In order to obtain thermoelectric materials with high figure of merit, the concept of Hollow (Vacuum) Quantum Structure or Effect and related thermoelectric materials design were proposed. To demonstrate the theory, the materials of (Bi0.15Sb0.85)2Te3 with porous structure have been fabricated. Their thermoelectric properties and the microstructure were investigated and compared with their density structure. It was found that the porous structure could improve their properties greatly.
2003, vol. 10, no. 5, pp.
44-47.
Abstract:
Abrasive wear characteristics of polyethylene, polystyrene, polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relative wear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and low temperature tempered steel 45 was used as a comparing material), and have a linear correlation with square roots of their cohesive energy densities. The coefficients of linear correlation is 0.949. Wear morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of the thermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing and fatiguing for the soft and tough ones.
Abrasive wear characteristics of polyethylene, polystyrene, polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relative wear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and low temperature tempered steel 45 was used as a comparing material), and have a linear correlation with square roots of their cohesive energy densities. The coefficients of linear correlation is 0.949. Wear morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of the thermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing and fatiguing for the soft and tough ones.
2003, vol. 10, no. 5, pp.
48-52.
Abstract:
The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The surface of solid steel plate was defatted, descaled, immersed (in K2ZrF6 flux aqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at the interface of steel-aluminum solid to liquid bonding under rapid solidification, the interface of bonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationship between bonding parameters (such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time) and thickness of Fe-Al compound layer at the interface was established by artificial neural networks (ANN) perfectly. The maximum of relative error between the output and the desired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacial shear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer 10.8 μm was got.
The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The surface of solid steel plate was defatted, descaled, immersed (in K2ZrF6 flux aqueous solution) and stoved. In order to determine the thickness of Fe-Al compound layer at the interface of steel-aluminum solid to liquid bonding under rapid solidification, the interface of bonding plate was investigated by SEM (Scanning Electron Microscope) experiment. The relationship between bonding parameters (such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time) and thickness of Fe-Al compound layer at the interface was established by artificial neural networks (ANN) perfectly. The maximum of relative error between the output and the desired output of the ANN is only 5.4%. From the bonding parameters for the largest interfacial shear strength of bonding plate (226℃ for preheat temperature of steel plate, 723℃ for temperature of aluminum liquid and 15.8 s for bonding time), the reasonable thickness of Fe-Al compound layer 10.8 μm was got.
2003, vol. 10, no. 5, pp.
53-58.
Abstract:
In order to understand the relation between microstructure of superalloy powders and its solidification progress, the processing parameters are optimized during plasma rotating electrode processing (PREP). It was predicted from the results that the droplet velocities, droplet temperature, and fractional solidification with flight time about FGH95 superalloy droplet have been carried out based on Newtonian heat transfer formulation coupled with the classical heterogeneous nucleation and the specific solidification process. It has been found that the droplet dynamic and thermal behavior is strongly affected by the distribution of droplet diameters,the proportion of cooling atmosphere, but is relatively unaffected by the droplet superheat.
In order to understand the relation between microstructure of superalloy powders and its solidification progress, the processing parameters are optimized during plasma rotating electrode processing (PREP). It was predicted from the results that the droplet velocities, droplet temperature, and fractional solidification with flight time about FGH95 superalloy droplet have been carried out based on Newtonian heat transfer formulation coupled with the classical heterogeneous nucleation and the specific solidification process. It has been found that the droplet dynamic and thermal behavior is strongly affected by the distribution of droplet diameters,the proportion of cooling atmosphere, but is relatively unaffected by the droplet superheat.
2003, vol. 10, no. 5, pp.
59-63.
Abstract:
The process of rolling step-shaft was simulated with the help of the FEM (Finite-Element Model) software-DEFORMTM 3D. The characteristics of metal flow in different periods were analyzed, and the curve of variety in non-round area at different crosssections of the rolled piece, the curve of variety in bulge volume and the curve of variety in non-column volume were obtained. On this base the method of tool design is worked out and validated by experiment.
The process of rolling step-shaft was simulated with the help of the FEM (Finite-Element Model) software-DEFORMTM 3D. The characteristics of metal flow in different periods were analyzed, and the curve of variety in non-round area at different crosssections of the rolled piece, the curve of variety in bulge volume and the curve of variety in non-column volume were obtained. On this base the method of tool design is worked out and validated by experiment.
2003, vol. 10, no. 5, pp.
64-68.
Abstract:
An experimental study of bioheat transfer characteristics induced by pulsed-laser irradiation was presented. The heat transfer characteristics of bio-materials, and the influences of pulse duration, power density, species of bio-materials, thickness and initial moisture content of bio-materials on heat transfer were studied in details. The experimental results indicate that the penetration and absorption of laser in bio-materials are considerable, the heat transfer inside the bio-materials should include the effects of volumetric absorption, pulse duration, power density, bio-materials thickness, and material species have a significant influence on the temperature variation.
An experimental study of bioheat transfer characteristics induced by pulsed-laser irradiation was presented. The heat transfer characteristics of bio-materials, and the influences of pulse duration, power density, species of bio-materials, thickness and initial moisture content of bio-materials on heat transfer were studied in details. The experimental results indicate that the penetration and absorption of laser in bio-materials are considerable, the heat transfer inside the bio-materials should include the effects of volumetric absorption, pulse duration, power density, bio-materials thickness, and material species have a significant influence on the temperature variation.
2003, vol. 10, no. 5, pp.
69-72.
Abstract:
The laser-field induced magnon amplification in a magnetic semiconductor quantum well under an external magnetic field was discussed, it is shown that when the laser frequency is near to the electron cyclotron frequency, no matter how weaker the laser field is, the magnon amplification always occurs. In case of fixed laser frequency, the optical absorption of magnons obeys the definite selection rule to the laser field strength. The rate of change of magnon occupation is calculated, and the amplification condition is given.
The laser-field induced magnon amplification in a magnetic semiconductor quantum well under an external magnetic field was discussed, it is shown that when the laser frequency is near to the electron cyclotron frequency, no matter how weaker the laser field is, the magnon amplification always occurs. In case of fixed laser frequency, the optical absorption of magnons obeys the definite selection rule to the laser field strength. The rate of change of magnon occupation is calculated, and the amplification condition is given.
2003, vol. 10, no. 5, pp.
73-77.
Abstract:
An online algorithm for training LS-SVM (Least Square Support Vector Machines) was proposed for the application of function estimation and classification. Online LS-SVM means that LS-SVM can be trained in an incremental way, and can be pruned to get sparse approximation in a decremental way. When a SV (Support Vector) is added or removed, the online algorithm avoids computing large-scale matrix inverse. Thus the computation cost is reduced. Online algorithm is especially useful to realistic function estimation problem such as system identification. The experiments with benchmark function estimation problem and classification problem show the validity of this online algorithm.
An online algorithm for training LS-SVM (Least Square Support Vector Machines) was proposed for the application of function estimation and classification. Online LS-SVM means that LS-SVM can be trained in an incremental way, and can be pruned to get sparse approximation in a decremental way. When a SV (Support Vector) is added or removed, the online algorithm avoids computing large-scale matrix inverse. Thus the computation cost is reduced. Online algorithm is especially useful to realistic function estimation problem such as system identification. The experiments with benchmark function estimation problem and classification problem show the validity of this online algorithm.
2003, vol. 10, no. 5, pp.
78-80.
Abstract:
The dissolving behaviour of Nb and Ti carbonitride precipitates in microalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electron microscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates in Nb-Ti microalloyed steel are (Nb, Ti)(C,N). With holding time increasing, the atomic ratio of Nb/Ti in precipitates decrease gradually. These precipitates still existe even after holding for 48 h at 1300℃ while Nb(C,N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the same temperature. These results show that formation and thermostability of precipitates are considerably influenced by interaction between Nb and Ti.
The dissolving behaviour of Nb and Ti carbonitride precipitates in microalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electron microscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates in Nb-Ti microalloyed steel are (Nb, Ti)(C,N). With holding time increasing, the atomic ratio of Nb/Ti in precipitates decrease gradually. These precipitates still existe even after holding for 48 h at 1300℃ while Nb(C,N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the same temperature. These results show that formation and thermostability of precipitates are considerably influenced by interaction between Nb and Ti.
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