Search2004 Vol. 11, No. 1
Display Method:
2004, vol. 11, no. 1, pp.
1-4.
Abstract:
In order to get cheap and excellent PEE (Powdery Emulsion Explosives), the model of optimizing selection on preparation of PEE was established by the Neural Net Theory (NNT). On the basis of some data in the study of PEE, the training, prediction and optimizing selection of the Neural Net (NN) model were finished by compiling procedures. The results indicate that the model is helpful to the preparation of PEE and worthy to extend and apply broadly.
In order to get cheap and excellent PEE (Powdery Emulsion Explosives), the model of optimizing selection on preparation of PEE was established by the Neural Net Theory (NNT). On the basis of some data in the study of PEE, the training, prediction and optimizing selection of the Neural Net (NN) model were finished by compiling procedures. The results indicate that the model is helpful to the preparation of PEE and worthy to extend and apply broadly.
2004, vol. 11, no. 1, pp.
5-9.
Abstract:
Fault rockburst is treated as a strain localization problem under dynamic loading condition considering strain gradient and strain rate. As a kind of dynamic fracture phenomena, rockburst has characteristics of strain localization, which is considered as a one-dimensional shear problem subjected to normal compressive stress and tangential shear stress. The constitutive relation of rock material is bilinear (elastic and strain softening) and sensitive to shear strain rate. The solutions proposed based on gradientdependent plasticity show that intense plastic strain is concentrated in fault band and the thickness of the band depends on the characteristic length of rock material. The post-peak stiffness of the fault band was determined according to the constitutive parameters of rock material and shear strain rate. Fault band undergoing strain softening and elastic rock mass outside the band constitute a system and the instability criterion of the system was proposed based on energy theory. The criterion depends on the constitutive relation of rock material, the structural size and the strain rate. The static result regardless of the strain rate is the special case of the present analytical solution. High strain rate can lead to instability of the system.
Fault rockburst is treated as a strain localization problem under dynamic loading condition considering strain gradient and strain rate. As a kind of dynamic fracture phenomena, rockburst has characteristics of strain localization, which is considered as a one-dimensional shear problem subjected to normal compressive stress and tangential shear stress. The constitutive relation of rock material is bilinear (elastic and strain softening) and sensitive to shear strain rate. The solutions proposed based on gradientdependent plasticity show that intense plastic strain is concentrated in fault band and the thickness of the band depends on the characteristic length of rock material. The post-peak stiffness of the fault band was determined according to the constitutive parameters of rock material and shear strain rate. Fault band undergoing strain softening and elastic rock mass outside the band constitute a system and the instability criterion of the system was proposed based on energy theory. The criterion depends on the constitutive relation of rock material, the structural size and the strain rate. The static result regardless of the strain rate is the special case of the present analytical solution. High strain rate can lead to instability of the system.
2004, vol. 11, no. 1, pp.
10-12.
Abstract:
In order to improve operation for shortening tap to tap time and saving electrical energy, on the base of no-linear reactance model, the electrical characteristics of the 50 t UHP-EAF in Fushun Special Steel Co. Ltd. were analyzed. Considering steelmaking process conditions, the optimum power-input diagrams were investigated, which can save energy, lower consumption, and raise productivity. This has been verified by production contrast tests. Application of the optimum curve in 50 t UHP-EAF indicates that research method is correct, the 50 t UHP-EAF runs smoothly with lowering electrical energy by 29.35 kW·h/t and shortening power on time by 3 min. The general steps of making optimum power-input specification is also given.
In order to improve operation for shortening tap to tap time and saving electrical energy, on the base of no-linear reactance model, the electrical characteristics of the 50 t UHP-EAF in Fushun Special Steel Co. Ltd. were analyzed. Considering steelmaking process conditions, the optimum power-input diagrams were investigated, which can save energy, lower consumption, and raise productivity. This has been verified by production contrast tests. Application of the optimum curve in 50 t UHP-EAF indicates that research method is correct, the 50 t UHP-EAF runs smoothly with lowering electrical energy by 29.35 kW·h/t and shortening power on time by 3 min. The general steps of making optimum power-input specification is also given.
2004, vol. 11, no. 1, pp.
13-17.
Abstract:
A 3-D transient mathematical model for laser cladding by powder feeding was developed to examine the macroscopic heat and momentum transport during the process, based on which a novel method for determining the configuration and thickness of cladding layer was presented. By using Lambert-Beer theorem and Mie′s theory, the interaction between powder stream and laser beam was treated to evoke their subtle effects on heat transfer and fluid flow in laser molten pool. The numerical study was performed in a co-ordinate system moving with the laser at a constant scanning speed. A fixed grid enthalpy-porosity approach was used,which predicted the evolutionary development of the laser molten pool. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. The results obtained by the simulation were coincident with those measured in experiment basically.
A 3-D transient mathematical model for laser cladding by powder feeding was developed to examine the macroscopic heat and momentum transport during the process, based on which a novel method for determining the configuration and thickness of cladding layer was presented. By using Lambert-Beer theorem and Mie′s theory, the interaction between powder stream and laser beam was treated to evoke their subtle effects on heat transfer and fluid flow in laser molten pool. The numerical study was performed in a co-ordinate system moving with the laser at a constant scanning speed. A fixed grid enthalpy-porosity approach was used,which predicted the evolutionary development of the laser molten pool. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. The results obtained by the simulation were coincident with those measured in experiment basically.
2004, vol. 11, no. 1, pp.
18-22.
Abstract:
A heat transfer model on the solidification process has been established on the basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & Steel Corporation, and the temperature field in the solidifying slab was calculated which was verified by the measured slab surface temperature. The influences of the main operating factors including casting speed, spray cooling patterns, superheat of melt and slab size on the solidification process were analyzed and the means of enhancing the slab temperature was brought forward. Raising the casting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving the cooling pattern at the lower segments of secondary cooling zone could improve the slab temperature effectively. And the increasing the superheat is adverse to the production of high temperature slab.
A heat transfer model on the solidification process has been established on the basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & Steel Corporation, and the temperature field in the solidifying slab was calculated which was verified by the measured slab surface temperature. The influences of the main operating factors including casting speed, spray cooling patterns, superheat of melt and slab size on the solidification process were analyzed and the means of enhancing the slab temperature was brought forward. Raising the casting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving the cooling pattern at the lower segments of secondary cooling zone could improve the slab temperature effectively. And the increasing the superheat is adverse to the production of high temperature slab.
2004, vol. 11, no. 1, pp.
23-29.
Abstract:
Some types of ZnO nanostructures with various shape and size, including tetrapod-like ZnO (T-ZnO) nanorods, nanowiresand nanoribbons, have been obtained by controlled growth process. The nanostructures of ZnO have been investigated by means offield-emission scanning electron microscope, transmission electron microscopy and high-resolution transmission electron micros-copy. The growth mechanisms of various ZnO nanosttrctures were proposed and discussed.
Some types of ZnO nanostructures with various shape and size, including tetrapod-like ZnO (T-ZnO) nanorods, nanowiresand nanoribbons, have been obtained by controlled growth process. The nanostructures of ZnO have been investigated by means offield-emission scanning electron microscope, transmission electron microscopy and high-resolution transmission electron micros-copy. The growth mechanisms of various ZnO nanosttrctures were proposed and discussed.
2004, vol. 11, no. 1, pp.
30-34.
Abstract:
Permalloy Ni80Fe20 films have been grown on thermal oxidized Si (111) wafers by magnetron sputtering at wellcontrolled substrate temperatures of 300, 500, 640 and 780 K in 0.65 Pa argon pressure. The base pressure was about l×10-4 Pa. The deposition rate was about 5 nm/min for all the films. The structure of the films was studied using X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the films was analyzed using scanning Auger microprobe. The resistance and magnetoresistance of the films were measured using four-point probe technique. The results show that the content of oxygen in the films decreases gradually with raising substrate temperature. In addition, the surface morphology of the films presents notable change with the increasing of the substrate temperature; the residual gases and defects decrease and the grains have coalesced evidently, and then the grains have grown up obviously and the texture of (111) orientation develops gradually in the growing film.As a result, the resistivity reduces apparently and magnetoresistance ratio increases markedly with raising substrate temperature.
Permalloy Ni80Fe20 films have been grown on thermal oxidized Si (111) wafers by magnetron sputtering at wellcontrolled substrate temperatures of 300, 500, 640 and 780 K in 0.65 Pa argon pressure. The base pressure was about l×10-4 Pa. The deposition rate was about 5 nm/min for all the films. The structure of the films was studied using X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the films was analyzed using scanning Auger microprobe. The resistance and magnetoresistance of the films were measured using four-point probe technique. The results show that the content of oxygen in the films decreases gradually with raising substrate temperature. In addition, the surface morphology of the films presents notable change with the increasing of the substrate temperature; the residual gases and defects decrease and the grains have coalesced evidently, and then the grains have grown up obviously and the texture of (111) orientation develops gradually in the growing film.As a result, the resistivity reduces apparently and magnetoresistance ratio increases markedly with raising substrate temperature.
2004, vol. 11, no. 1, pp.
35-38.
Abstract:
The stacking fault energies of Ti-46Al-8.5Nb-0.2W alloy at 298 K and 1273 K were determined. The principle for the determination of the stacking fault energies is based on the fact that the stacking fault energy and the elastic interaction energy acting on the dissociated partial dislocations are equal. After the compress deformations with the strain of 0.2% at 298 K and 1273 K, and water quench to maintain the dislocation structures deformed at 1273 K, the dissociation distances between two partial dislocations were determined by weak beam transmission electron microscopy (WBTEM) technique. Based on these dissociation distances and the corresponding calculation method, the stacking fault energies were determined to be 77-81 mJ/m2 at 298 K and to be 57-60mJ/m2 at 1273 K respectively.
The stacking fault energies of Ti-46Al-8.5Nb-0.2W alloy at 298 K and 1273 K were determined. The principle for the determination of the stacking fault energies is based on the fact that the stacking fault energy and the elastic interaction energy acting on the dissociated partial dislocations are equal. After the compress deformations with the strain of 0.2% at 298 K and 1273 K, and water quench to maintain the dislocation structures deformed at 1273 K, the dissociation distances between two partial dislocations were determined by weak beam transmission electron microscopy (WBTEM) technique. Based on these dissociation distances and the corresponding calculation method, the stacking fault energies were determined to be 77-81 mJ/m2 at 298 K and to be 57-60mJ/m2 at 1273 K respectively.
2004, vol. 11, no. 1, pp.
39-43.
Abstract:
SiC whiskers with ″rosary bead″ morphology were synthesized using suitable silicon source and carbon source through solid reaction at the temperature above 1537 K. The diameter and length of the SiC whiskers were about 0.1-1.0 μm and 20-100 μm,respectively. The largest diameter of their enlarged ends of the whiskers was about 0.2-1.0 μm, and it gradually and smoothly decreased to the size of the plain part of the whiskers. The results of X-ray diffraction analysis show that the crystalline structure of the obtained SiC whiskers is β-SiC. It is considered that the SiC whiskers grow via a vapor-solid mechanism.
SiC whiskers with ″rosary bead″ morphology were synthesized using suitable silicon source and carbon source through solid reaction at the temperature above 1537 K. The diameter and length of the SiC whiskers were about 0.1-1.0 μm and 20-100 μm,respectively. The largest diameter of their enlarged ends of the whiskers was about 0.2-1.0 μm, and it gradually and smoothly decreased to the size of the plain part of the whiskers. The results of X-ray diffraction analysis show that the crystalline structure of the obtained SiC whiskers is β-SiC. It is considered that the SiC whiskers grow via a vapor-solid mechanism.
2004, vol. 11, no. 1, pp.
44-47.
Abstract:
A very simple model based on the Quadrupole method was used in the theoretical analysis of thermal diffusivity of composite materials of Cu-PVC, PVC-Cu-PVC, and Cu-PVC-Cu. The use of MATLAB software with a return to real space using the Stehfest algorithm makes the time of calculation very short. The thermal responses on the rear face of each considered sample, which determine the thermal diffusivity were represented. A mathematical demonstration which confirmed the results was given. Thermal diffusivity determined from the rear face thermal responses were compared with the results of the thermal diffusivity calculated by considering the composite materials to be homogeneous, and a discussion on the two kinds of results was provided.
A very simple model based on the Quadrupole method was used in the theoretical analysis of thermal diffusivity of composite materials of Cu-PVC, PVC-Cu-PVC, and Cu-PVC-Cu. The use of MATLAB software with a return to real space using the Stehfest algorithm makes the time of calculation very short. The thermal responses on the rear face of each considered sample, which determine the thermal diffusivity were represented. A mathematical demonstration which confirmed the results was given. Thermal diffusivity determined from the rear face thermal responses were compared with the results of the thermal diffusivity calculated by considering the composite materials to be homogeneous, and a discussion on the two kinds of results was provided.
2004, vol. 11, no. 1, pp.
48-51.
Abstract:
Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2·4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders.At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na+ ions. The as-prepared colloidal Nb2O5·nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1 h, and the assintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.
Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2·4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders.At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na+ ions. The as-prepared colloidal Nb2O5·nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1 h, and the assintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.
2004, vol. 11, no. 1, pp.
52-56.
Abstract:
The effects of thickness and types of gold plating on the resistance to high temperature discoloration of gold plating on cavity surface of ceramic package were investigated. It was found that the thicker gold plating, the less discoloration degree for ceramic packages. Non-cyanide gold plating performed better resistance to high-temperature aging than cyanide gold plating. The relationship between the gold plating thickness and the amount of diffused Ni to the gold plating of ceramic packages with Au/Ni and Au/Ni-Co platings after heating at 420℃ for 15 min was also studied. When the gold plating thickness reach 2.0 μm and 1.6 μm for Au/Ni and Au/Ni-Co plating systems, respectively, no discoloration was observed on the gold plating surface of cavity, and the corresponding diffused Ni amounts (mass fraction) are 1.0% and 0.4%, while the diffused Co to the gold plating is 0.04%.
The effects of thickness and types of gold plating on the resistance to high temperature discoloration of gold plating on cavity surface of ceramic package were investigated. It was found that the thicker gold plating, the less discoloration degree for ceramic packages. Non-cyanide gold plating performed better resistance to high-temperature aging than cyanide gold plating. The relationship between the gold plating thickness and the amount of diffused Ni to the gold plating of ceramic packages with Au/Ni and Au/Ni-Co platings after heating at 420℃ for 15 min was also studied. When the gold plating thickness reach 2.0 μm and 1.6 μm for Au/Ni and Au/Ni-Co plating systems, respectively, no discoloration was observed on the gold plating surface of cavity, and the corresponding diffused Ni amounts (mass fraction) are 1.0% and 0.4%, while the diffused Co to the gold plating is 0.04%.
2004, vol. 11, no. 1, pp.
57-61.
Abstract:
Electron microscopy and X-ray Energy Dispersive Spectroscopy (XEDS) study on influence of Cu on low carbon hot strips produced by CSP (Compact Strip Production) process has been carried out. The results indicated that copper segregation and enrichment at interfacial layer between oxidized surface and steel matrix is the key factor, which results in microcracks and edge flaws on the strips. The primary considerations to prevent detrimental effects from Cu include controlling copper content in proper level, higher soaking temperature and non-oxidizable atmosphere during soaking. Copper sulfide precipitates with nanometers in size were observed, they may be beneficial to the properties of CSP products, and influence of Cu on quality of CSP hot strips is discussed.
Electron microscopy and X-ray Energy Dispersive Spectroscopy (XEDS) study on influence of Cu on low carbon hot strips produced by CSP (Compact Strip Production) process has been carried out. The results indicated that copper segregation and enrichment at interfacial layer between oxidized surface and steel matrix is the key factor, which results in microcracks and edge flaws on the strips. The primary considerations to prevent detrimental effects from Cu include controlling copper content in proper level, higher soaking temperature and non-oxidizable atmosphere during soaking. Copper sulfide precipitates with nanometers in size were observed, they may be beneficial to the properties of CSP products, and influence of Cu on quality of CSP hot strips is discussed.
2004, vol. 11, no. 1, pp.
62-66.
Abstract:
The hardness, tensile strength and impact toughness of one quenched and tempered steel with nominal composition of Fe0.25C-3.0Cr-3.0Mo-0.6Ni-0.1Nb (mass fraction) both at room temperature and at elevated temperatures were investigated in order to develop high-strength steel for long-life gun barrel use. It is found that the steel has lower decrease rate of tensile strength at elevated temperature in comparison with the commonly used G4335V high-strength gun steel, which contains higher Ni and lower Cr and Mo contents. The high elevated-temperature strength of the steel is attributed to the strong secondary hardening effect and high tempering softening resistance caused by the tempering precipitation of fine Mo-rich M2C carbides in the α-Fe matrix. The experimental steel is not susceptible to secondary hardening embrittlement, meanwhile, its room-temperature impact energy is much higher than the normal requirement of impact toughness for high strength gun steels. Therefore, the steel is suitable for production of long-life high-strength gun barrels with the combination of superior elevated-temperature strength and good impact toughness.
The hardness, tensile strength and impact toughness of one quenched and tempered steel with nominal composition of Fe0.25C-3.0Cr-3.0Mo-0.6Ni-0.1Nb (mass fraction) both at room temperature and at elevated temperatures were investigated in order to develop high-strength steel for long-life gun barrel use. It is found that the steel has lower decrease rate of tensile strength at elevated temperature in comparison with the commonly used G4335V high-strength gun steel, which contains higher Ni and lower Cr and Mo contents. The high elevated-temperature strength of the steel is attributed to the strong secondary hardening effect and high tempering softening resistance caused by the tempering precipitation of fine Mo-rich M2C carbides in the α-Fe matrix. The experimental steel is not susceptible to secondary hardening embrittlement, meanwhile, its room-temperature impact energy is much higher than the normal requirement of impact toughness for high strength gun steels. Therefore, the steel is suitable for production of long-life high-strength gun barrels with the combination of superior elevated-temperature strength and good impact toughness.
2004, vol. 11, no. 1, pp.
67-70.
Abstract:
FeSi2 based thermoelectric materials have been prepared by melt spinning and vacuum hot pressing. Most of the rapidly solidified (melt spinning) powders are thin flakes with a thickness less than 0.1 mm. Scanning electron microscope (SEM) surface profiles show there are further finer grain structures with the characteristic size of about 100 nm in a flake. The samples obtained by hot uniaxial pressing (HUP) in vacuum have densities higher than 90% the theoretical density of the materials. It was found by SEM observations that the microstructures are very different for vertical and parallel sections of the HUP samples. X-ray diffraction (XRD)analyses show there are some texture features in the samples. It is considered that the textures of the samples are originated from the orientation of the flakes that tended to align perpendicular to the hot press axis. WSi2 was introduced into the powders unexpectedly during melting process before the rapid solidification, but it makes the microstructures more easily to be explained.
FeSi2 based thermoelectric materials have been prepared by melt spinning and vacuum hot pressing. Most of the rapidly solidified (melt spinning) powders are thin flakes with a thickness less than 0.1 mm. Scanning electron microscope (SEM) surface profiles show there are further finer grain structures with the characteristic size of about 100 nm in a flake. The samples obtained by hot uniaxial pressing (HUP) in vacuum have densities higher than 90% the theoretical density of the materials. It was found by SEM observations that the microstructures are very different for vertical and parallel sections of the HUP samples. X-ray diffraction (XRD)analyses show there are some texture features in the samples. It is considered that the textures of the samples are originated from the orientation of the flakes that tended to align perpendicular to the hot press axis. WSi2 was introduced into the powders unexpectedly during melting process before the rapid solidification, but it makes the microstructures more easily to be explained.
2004, vol. 11, no. 1, pp.
71-74.
Abstract:
To achieve high carbon hard-facing weld metals with both high hardness and crack resistance, strong carbide forming elements Ti, Nb and V were alloyed into the weld metals, and their effect on the formation of carbides and the matrix microstructure were studied. Electron Probe Microanalysis (EPMA), Energy Dispersive Spectroscopy(EDS) and Transmission Electron Microscopy(TEM) were adopted to investigate the microstructure, then thermodynamics of the formation of carbides was calculated and their effect on the matrix was further discussed. It is revealed that Nb, Ti and V influence strongly the distribution and existing state of carbon, inducing precipitation of carbides accompanying with the depletion of carbon in matrix. But when only V are alloyed as carbide forming element, the carbides are scarce and distributed along grain boundaries, and the hard-facing alloy is too hard, while the using of only Nb or Ti could not reinforce the weld metals effectively. The hard-facing alloy reinforced with Nb, V and Ti can form dispersive fine carbides and low carbon martensite matrix.
To achieve high carbon hard-facing weld metals with both high hardness and crack resistance, strong carbide forming elements Ti, Nb and V were alloyed into the weld metals, and their effect on the formation of carbides and the matrix microstructure were studied. Electron Probe Microanalysis (EPMA), Energy Dispersive Spectroscopy(EDS) and Transmission Electron Microscopy(TEM) were adopted to investigate the microstructure, then thermodynamics of the formation of carbides was calculated and their effect on the matrix was further discussed. It is revealed that Nb, Ti and V influence strongly the distribution and existing state of carbon, inducing precipitation of carbides accompanying with the depletion of carbon in matrix. But when only V are alloyed as carbide forming element, the carbides are scarce and distributed along grain boundaries, and the hard-facing alloy is too hard, while the using of only Nb or Ti could not reinforce the weld metals effectively. The hard-facing alloy reinforced with Nb, V and Ti can form dispersive fine carbides and low carbon martensite matrix.
2004, vol. 11, no. 1, pp.
75-80.
Abstract:
Effect of chemical component on shape memory effect (SME) of Fe-Mn-Si-Ni-C-RE shape memory alloys was studied by bent measurement, thermal cycle training, SEM etc. Results of study indicate that the alloys with high Mn content (25%) appeare better SME, especially in lower strain. SME improves evidently when Si is higher content, especially it′s range from 3% up to 4%.But brittleness of Fe-Mn-Si-Ni-C-RE alloy increases by increasing the Si content. SME of the alloy is weakening gradually as carbon content increases under small strain (3%). But in the condition of large strain (above 6%), SME of the alloy whose carbon content ranges from 0.1% to 0.12% shows small decreasing range, especially of alloy with the addition of compound RE.
Effect of chemical component on shape memory effect (SME) of Fe-Mn-Si-Ni-C-RE shape memory alloys was studied by bent measurement, thermal cycle training, SEM etc. Results of study indicate that the alloys with high Mn content (25%) appeare better SME, especially in lower strain. SME improves evidently when Si is higher content, especially it′s range from 3% up to 4%.But brittleness of Fe-Mn-Si-Ni-C-RE alloy increases by increasing the Si content. SME of the alloy is weakening gradually as carbon content increases under small strain (3%). But in the condition of large strain (above 6%), SME of the alloy whose carbon content ranges from 0.1% to 0.12% shows small decreasing range, especially of alloy with the addition of compound RE.
2004, vol. 11, no. 1, pp.
81-84.
Abstract:
To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon′s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys.
To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon′s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys.
2004, vol. 11, no. 1, pp.
85-89.
Abstract:
Through the vacuum diffusion welding SiCp/ZL101 aluminum with Ni interlayer, the effect of welding parameter and the thickness property of Ni on the welded joint was investigated, and the optimal welding parameters were put forward at the same time.The microstructure of joint was analyzed by means of optical-microscope, scanning electron microscope (SEM) in order to study the relationship between the macro-properties of joint and the microstructure. The results show that diffusion welding with Ni interlayer can be used for welding aluminum matrix composites SiCp/ZL101 successfully. Under the welding parameters T=560℃, P=5 MPa,t=60 min, H=14 μm, the bonding strength of welded joint can up to 121 MPa. Moreover, the thickness of interlayer should match with the size of reinforced particles. If the thickness of interlayer is too thin, it would have no effect on the welded joint beneficially.If the thickness of interlayer is too thick, it would cause the "no-reinforcement zone" to appear.
Through the vacuum diffusion welding SiCp/ZL101 aluminum with Ni interlayer, the effect of welding parameter and the thickness property of Ni on the welded joint was investigated, and the optimal welding parameters were put forward at the same time.The microstructure of joint was analyzed by means of optical-microscope, scanning electron microscope (SEM) in order to study the relationship between the macro-properties of joint and the microstructure. The results show that diffusion welding with Ni interlayer can be used for welding aluminum matrix composites SiCp/ZL101 successfully. Under the welding parameters T=560℃, P=5 MPa,t=60 min, H=14 μm, the bonding strength of welded joint can up to 121 MPa. Moreover, the thickness of interlayer should match with the size of reinforced particles. If the thickness of interlayer is too thin, it would have no effect on the welded joint beneficially.If the thickness of interlayer is too thick, it would cause the "no-reinforcement zone" to appear.
2004, vol. 11, no. 1, pp.
90-93.
Abstract:
A multi-mode adaptive controller was proposed. The controller features in the combination of Bang-bang and Fuzzy PID controls with state predictor. When large error exists, the controller operates in Bang-bang mode, otherwise it works as a fuzzy PID controller. For only few parameters to be adjusted, the real time controlled system achieveed good stability and fast response. Furthermore, the introduction of state observer was also discussed to extend the capability of the proposed controller to the plant with time-delay factors. The classical PID controller and the multi-mode controller were applied to the same second-order system successively. By comparison of the simulation results, the effectiveness of the controller were shown. At last, on electric-wire production line, this approach was practiced to control electric-wire diameter with an additive random disturbance signal. The test result further proved the effectiveness of the multi-mode controller.
A multi-mode adaptive controller was proposed. The controller features in the combination of Bang-bang and Fuzzy PID controls with state predictor. When large error exists, the controller operates in Bang-bang mode, otherwise it works as a fuzzy PID controller. For only few parameters to be adjusted, the real time controlled system achieveed good stability and fast response. Furthermore, the introduction of state observer was also discussed to extend the capability of the proposed controller to the plant with time-delay factors. The classical PID controller and the multi-mode controller were applied to the same second-order system successively. By comparison of the simulation results, the effectiveness of the controller were shown. At last, on electric-wire production line, this approach was practiced to control electric-wire diameter with an additive random disturbance signal. The test result further proved the effectiveness of the multi-mode controller.
2004, vol. 11, no. 1, pp.
94-96.
Abstract:
A great deal of research and practical production indicated that a perfect shape control system needs a precise prediction model of roll wear. According to the practical wear curve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, the model of wear curve caused by one single strip was established. The prediction of work-roll wear was achieved by combining Fortran language and practical technology parameters. The calculated results agreed well with the measured.
A great deal of research and practical production indicated that a perfect shape control system needs a precise prediction model of roll wear. According to the practical wear curve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, the model of wear curve caused by one single strip was established. The prediction of work-roll wear was achieved by combining Fortran language and practical technology parameters. The calculated results agreed well with the measured.
Submit Manuscript
E-mail alert
RSS
