Search2008 Vol. 15, No. 1
Display Method:
2008, vol. 15, no. 1, pp.
1-4.
https://doi.org/10.1016/S1005-8850(08)60001-8
Abstract:
The Kaiser effect is formally described as the absence of detectable acoustic emission (AE) events until the load imposed on the material exceeds the previous applied level and is usually used to estimate geostress. By focusing on the heterogeneity of rock material, the mechanism of the Kaiser effect under cyclic loading is analyzed based on statistic damage mechanics. Two groups of granite specimens have been cyclically loaded with two different loading paths to verify the theoretical results. The heterogeneity of rock is the real reason that causes irrecoverable damage on the Kaiser effect of acoustic emission in cyclic loading. The Kaiser effect reflects the damaged state in rocks rather than the previous stress imposed on it. Applications for using the Kaiser effect to estimate geostress were discussed here. It is shown that the commonly used uniaxial loading method for estimating geostress is not in accor-dance with the theoretical and experimental results. The analysis is of importance to use the Kaiser effect correctly for estimating geostress or in other fields.
The Kaiser effect is formally described as the absence of detectable acoustic emission (AE) events until the load imposed on the material exceeds the previous applied level and is usually used to estimate geostress. By focusing on the heterogeneity of rock material, the mechanism of the Kaiser effect under cyclic loading is analyzed based on statistic damage mechanics. Two groups of granite specimens have been cyclically loaded with two different loading paths to verify the theoretical results. The heterogeneity of rock is the real reason that causes irrecoverable damage on the Kaiser effect of acoustic emission in cyclic loading. The Kaiser effect reflects the damaged state in rocks rather than the previous stress imposed on it. Applications for using the Kaiser effect to estimate geostress were discussed here. It is shown that the commonly used uniaxial loading method for estimating geostress is not in accor-dance with the theoretical and experimental results. The analysis is of importance to use the Kaiser effect correctly for estimating geostress or in other fields.
2008, vol. 15, no. 1, pp.
5-9.
https://doi.org/10.1016/S1005-8850(08)60002-X
Abstract:
The effects of lance height and bottom blown flowrate on the mixed time, the splashing amount, the penetrating depth, and the level fluctuation of an 85 t combined blown converter have been studied using a water model. The results show that the maximal stirring energy is provided to the bath at the top lance height of about 50-100 mm. When the top lance height is in the range of 90-110 mm, the splashing amount caused by the top jet can reach the maximal value. The appropriate operational parameters of Chongqing Iron and Steel Company (CISC) converter have been established that the top lance height is 1600-1760 mm and the bottom blowing flowrate is 240-480 Nm3/h in the primary phase of a heat, 1100-1300 mm and 160-200 Nm3/h in the second phase, and 1040-1120 mm and 200-350 Nm3/h in the end phase. Also, the trial shows that the metallurgical result of the studied blow pattern is better than that of the former pattern. At the starting 3-4 min of a heat, the strong splashing is eliminated.
The effects of lance height and bottom blown flowrate on the mixed time, the splashing amount, the penetrating depth, and the level fluctuation of an 85 t combined blown converter have been studied using a water model. The results show that the maximal stirring energy is provided to the bath at the top lance height of about 50-100 mm. When the top lance height is in the range of 90-110 mm, the splashing amount caused by the top jet can reach the maximal value. The appropriate operational parameters of Chongqing Iron and Steel Company (CISC) converter have been established that the top lance height is 1600-1760 mm and the bottom blowing flowrate is 240-480 Nm3/h in the primary phase of a heat, 1100-1300 mm and 160-200 Nm3/h in the second phase, and 1040-1120 mm and 200-350 Nm3/h in the end phase. Also, the trial shows that the metallurgical result of the studied blow pattern is better than that of the former pattern. At the starting 3-4 min of a heat, the strong splashing is eliminated.
2008, vol. 15, no. 1, pp.
10-16.
https://doi.org/10.1016/S1005-8850(08)60003-1
Abstract:
The quantificational and normative design is the precondition of improving the design of copper staves for blast furnaces. Based on a 3-dimensional temperature field calculation model, from the view point of heat transfer and long campaigns note with the core of forming accretion, the forming-accretion-ability (FAA) and the rib hot surface maximum temperature difference (△Tmax) as quantificational indexes to direct and evaluate the design of copper staves for blast furnaces were presented. The application of the two indexes in design essentially embodies the new long campaigns in the stage of design. With the application of the two indexes, good results can be obtained. Firstly, it was suggested that the rib height of a copper stave can be reduced to 15 mm, which is a new method and theory for the reduction of copper staves. Secondly, the influence of insert on FAA and △Tmax, is decided by the volume of insert. According to this, the principle of design for the hot surface geometry of copper staves was put forward that the ratio of the rib hot surface to the copper stave hot surface (abbreviated as the ratio of rib to stave) must be maintained in the range of 45% to 55%; for the present copper stave with a 35-40 mm thick rib, the ratio of rib to stave in the range of 50% to 55% can optimize the design of copper staves; for the copper stave with a smaller rib thickness, for example 15 ram, the ratio of rib to stave in the range of 45% to 50% can optimize the design of copper staves. It can be summarized that the thicker the rib thickness, the larger is the ratio of rib to stave.
The quantificational and normative design is the precondition of improving the design of copper staves for blast furnaces. Based on a 3-dimensional temperature field calculation model, from the view point of heat transfer and long campaigns note with the core of forming accretion, the forming-accretion-ability (FAA) and the rib hot surface maximum temperature difference (△Tmax) as quantificational indexes to direct and evaluate the design of copper staves for blast furnaces were presented. The application of the two indexes in design essentially embodies the new long campaigns in the stage of design. With the application of the two indexes, good results can be obtained. Firstly, it was suggested that the rib height of a copper stave can be reduced to 15 mm, which is a new method and theory for the reduction of copper staves. Secondly, the influence of insert on FAA and △Tmax, is decided by the volume of insert. According to this, the principle of design for the hot surface geometry of copper staves was put forward that the ratio of the rib hot surface to the copper stave hot surface (abbreviated as the ratio of rib to stave) must be maintained in the range of 45% to 55%; for the present copper stave with a 35-40 mm thick rib, the ratio of rib to stave in the range of 50% to 55% can optimize the design of copper staves; for the copper stave with a smaller rib thickness, for example 15 ram, the ratio of rib to stave in the range of 45% to 50% can optimize the design of copper staves. It can be summarized that the thicker the rib thickness, the larger is the ratio of rib to stave.
2008, vol. 15, no. 1, pp.
17-23.
https://doi.org/10.1016/S1005-8850(08)60004-3
Abstract:
A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secondary cooling system for automobile steel. Moreover, it was already applied to real production. The calculated temperature distribution and solidification trend of blooms had offered a reliable theory for optimizing the solidifying process of blooms, increasing withdrawal speed, and improving bloom quality. Meanwhile, a new secondary cooling system was designed to optimize a secondary cooling water distribution, including choice and arrangements of nozzles, calculation of cooling water quantity, and so on.
A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secondary cooling system for automobile steel. Moreover, it was already applied to real production. The calculated temperature distribution and solidification trend of blooms had offered a reliable theory for optimizing the solidifying process of blooms, increasing withdrawal speed, and improving bloom quality. Meanwhile, a new secondary cooling system was designed to optimize a secondary cooling water distribution, including choice and arrangements of nozzles, calculation of cooling water quantity, and so on.
2008, vol. 15, no. 1, pp.
24-28.
https://doi.org/10.1016/S1005-8850(08)60005-5
Abstract:
To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while free clay minerals with a size of 〈38 μm are mainly iosidefite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe3+ ion content of less than 5 g·L-1 was recovered as feeding water in the wet magnetic separation procedure.
To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while free clay minerals with a size of 〈38 μm are mainly iosidefite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe3+ ion content of less than 5 g·L-1 was recovered as feeding water in the wet magnetic separation procedure.
2008, vol. 15, no. 1, pp.
29-33.
https://doi.org/10.1016/S1005-8850(08)60006-7
Abstract:
The erosion behavior of austempered ductile irons austenized at different temperatures was studied. The results indicate that the erosion rate well correlates with the mechanical properties. At high impact angles, increasing ductility and mechanical energy density results in decreasing erosion rate, whereas increasing hardness reduces the erosion rate at low impact angles.
The erosion behavior of austempered ductile irons austenized at different temperatures was studied. The results indicate that the erosion rate well correlates with the mechanical properties. At high impact angles, increasing ductility and mechanical energy density results in decreasing erosion rate, whereas increasing hardness reduces the erosion rate at low impact angles.
2008, vol. 15, no. 1, pp.
34-37.
https://doi.org/10.1016/S1005-8850(08)60007-9
Abstract:
The microstructure analysis was employed for the ferrific stainless steel (SUS430) with the carbon content from 0.029wt% to 0.100wt% under the simulated heating process condition. The higher carbon sample (430H) contains the duplex phase microstructure at the temperature of 1150℃; on the other hand, the lower carbon content sample (430L) does not touch two phase area even at the temperature of 1450℃ and has the single phase ferritic microstructure. The carbon content need be well controlled for the 430 ferritic stainless steel since it can significantly affect the heating process curve, and the heating process may not be done in the two phase area due to the uncontrolled carbon content. With the low carbon content and the proper soaking time, the grain size is not sensitive to the heating process temperature and the soaking time. In the present heat treatment experiments, the soaking time is about 10 min, and the processing parameters can be chosen according to the requirement of the gross energy, the efficiency and the continual forming.
The microstructure analysis was employed for the ferrific stainless steel (SUS430) with the carbon content from 0.029wt% to 0.100wt% under the simulated heating process condition. The higher carbon sample (430H) contains the duplex phase microstructure at the temperature of 1150℃; on the other hand, the lower carbon content sample (430L) does not touch two phase area even at the temperature of 1450℃ and has the single phase ferritic microstructure. The carbon content need be well controlled for the 430 ferritic stainless steel since it can significantly affect the heating process curve, and the heating process may not be done in the two phase area due to the uncontrolled carbon content. With the low carbon content and the proper soaking time, the grain size is not sensitive to the heating process temperature and the soaking time. In the present heat treatment experiments, the soaking time is about 10 min, and the processing parameters can be chosen according to the requirement of the gross energy, the efficiency and the continual forming.
2008, vol. 15, no. 1, pp.
38-42.
https://doi.org/10.1016/S1005-8850(08)60008-0
Abstract:
The effect of tempering temperature on the microstructure and mechanical properties of ultra-high strength, copperbearing, low-carbon bainitic steel has been investigated in the experiment. The results showed that the microstructure was mainly the laths of bainite in the as-quenched steel. The bainitic laths were restored and combined after the steel tempered at various temperatures. There were rnartensite/austenite (M/A) islands and numerous dislocations within and between the bainitic laths, while very t-me precipitates of ε-Cu were also observed within the laths. With increasing the tempered temperature from 400 to 600℃, the yield strength (YS) increased from 877 to 957 MPa, whereas the ultimate tensile strength (UTS) decreased from 1020 to 985 MPa. The Charpy V-notch (CVN) varied from 68.5 to 42 J, and the value was minimal for the steel tempered at 500℃.
The effect of tempering temperature on the microstructure and mechanical properties of ultra-high strength, copperbearing, low-carbon bainitic steel has been investigated in the experiment. The results showed that the microstructure was mainly the laths of bainite in the as-quenched steel. The bainitic laths were restored and combined after the steel tempered at various temperatures. There were rnartensite/austenite (M/A) islands and numerous dislocations within and between the bainitic laths, while very t-me precipitates of ε-Cu were also observed within the laths. With increasing the tempered temperature from 400 to 600℃, the yield strength (YS) increased from 877 to 957 MPa, whereas the ultimate tensile strength (UTS) decreased from 1020 to 985 MPa. The Charpy V-notch (CVN) varied from 68.5 to 42 J, and the value was minimal for the steel tempered at 500℃.
2008, vol. 15, no. 1, pp.
43-47.
https://doi.org/10.1016/S1005-8850(08)60009-2
Abstract:
The crystal plasticity finite element modeling (CPFEM) is realized in commercial finite element code ABAQUS with UMAT subroutine on the basis of the crystal plasticity theory of rate dependent polycrystal constitutive relations in the mesoscopic scale. The initial orientations obtained by electron backscatter diffraction (EBSD) are directly input into the CPFEM to simulate the mechanical response of polycrystalline 1050 pure Al in uniaxial tensile deformation. Two polycrystal models and two tensile strain rates were used in the simulations. The stress-strain curves of tensile deformation were analyzed. The predictions and the corresponding experiment result show reasonable agreement and slight deviation with experiments. The flow true stress of strain rate 0.01 s-1 is higher than that of strain rate 0.001 s-1. At the strain less than 0.05, the stress saturated rate of the experiment is higher than the simulated results. However, the stress saturated rate of the experiment becomes gentler than the corresponding simulated predictions at the strain over 0.05. Also, necking was simulated by the two models, but the necking strain is not well predicted. Tensile textures at strain 0.25 were predicted at the low strain rate of 0.001 s-1. The predictions are in good accord with the experimental results.
The crystal plasticity finite element modeling (CPFEM) is realized in commercial finite element code ABAQUS with UMAT subroutine on the basis of the crystal plasticity theory of rate dependent polycrystal constitutive relations in the mesoscopic scale. The initial orientations obtained by electron backscatter diffraction (EBSD) are directly input into the CPFEM to simulate the mechanical response of polycrystalline 1050 pure Al in uniaxial tensile deformation. Two polycrystal models and two tensile strain rates were used in the simulations. The stress-strain curves of tensile deformation were analyzed. The predictions and the corresponding experiment result show reasonable agreement and slight deviation with experiments. The flow true stress of strain rate 0.01 s-1 is higher than that of strain rate 0.001 s-1. At the strain less than 0.05, the stress saturated rate of the experiment is higher than the simulated results. However, the stress saturated rate of the experiment becomes gentler than the corresponding simulated predictions at the strain over 0.05. Also, necking was simulated by the two models, but the necking strain is not well predicted. Tensile textures at strain 0.25 were predicted at the low strain rate of 0.001 s-1. The predictions are in good accord with the experimental results.
2008, vol. 15, no. 1, pp.
48-52.
https://doi.org/10.1016/S1005-8850(08)60010-9
Abstract:
The effects of slurry temperature, injection pressure, and piston velocity on the rheo-filling ability of semisolid A356 alloys were studied by the reho-diecasting methods. The results show that the slurry temperature of the semi-solid A356 aluminum alloy has an important effect on the filling ability; the higher the slurry temperature, the better is the filling ability, and the appropriate slurry temperature for rheo-filling is in the range of 585-595℃. The injection pressure also has a great effect on the filling ability, and it is appropriate to the rheo-filling when the injection pressure is in the range of 15-25 MPa. The piston velocity also has a great effect on the filling ability, and it is appropriate to the rheo-filling when the piston velocity is in the range of 0.072-0.12 m/s. The filling ability of the slurry prepared by low superheat pouring with weak electromagnetic stirring is very good and the microstructural distribution in the rheo-formed die castings is homogeneous, which is advantageous to the high quality die casting.
The effects of slurry temperature, injection pressure, and piston velocity on the rheo-filling ability of semisolid A356 alloys were studied by the reho-diecasting methods. The results show that the slurry temperature of the semi-solid A356 aluminum alloy has an important effect on the filling ability; the higher the slurry temperature, the better is the filling ability, and the appropriate slurry temperature for rheo-filling is in the range of 585-595℃. The injection pressure also has a great effect on the filling ability, and it is appropriate to the rheo-filling when the injection pressure is in the range of 15-25 MPa. The piston velocity also has a great effect on the filling ability, and it is appropriate to the rheo-filling when the piston velocity is in the range of 0.072-0.12 m/s. The filling ability of the slurry prepared by low superheat pouring with weak electromagnetic stirring is very good and the microstructural distribution in the rheo-formed die castings is homogeneous, which is advantageous to the high quality die casting.
2008, vol. 15, no. 1, pp.
53-57.
https://doi.org/10.1016/S1005-8850(08)60011-0
Abstract:
〈110〉 oriented rods of TbDyFe giant magnetostrictive alloys have been prepared with the help of the zone melting directional solidification technique with a high temperature gradient. To acquire optimal magnetostrictive properties at low magnetic field, the TbDyFe alloys have been heat-treated at different temperatures and cooled at different rates. The relationships between the process of the heat treatment, microstructure, defects, and magnetostrictive properties of the TbDyFe materials have been studied.
〈110〉 oriented rods of TbDyFe giant magnetostrictive alloys have been prepared with the help of the zone melting directional solidification technique with a high temperature gradient. To acquire optimal magnetostrictive properties at low magnetic field, the TbDyFe alloys have been heat-treated at different temperatures and cooled at different rates. The relationships between the process of the heat treatment, microstructure, defects, and magnetostrictive properties of the TbDyFe materials have been studied.
2008, vol. 15, no. 1, pp.
58-61.
https://doi.org/10.1016/S1005-8850(08)60012-2
Abstract:
Two-dimension (2D) fused-silica fiber reinforced porous silicon nitride matrix composites were fabricated using slurry impregnation and cyclic infiltration with colloidal silica sol. The microstructure and fracture surface were characterized by SEM, the mechanical behavior was investigated by three-point bending test, and the dielectric constant was also measured by impedance analysis. The microstructure showed that the fiber and the matrix had a physical bonding, forming a clearance interface. The mechanical behavior suggested that the porous matrix acted as crack deflection, and the fracture surface had a lot of fiber pull-out. However, the interlaminar shear strength was not so good. The dielectric constant of the composites at room temperature was about 2.8-3.1. The relatively low dielectric constant and non-catastrophic failure indicated the potential application in the radome materials field.
Two-dimension (2D) fused-silica fiber reinforced porous silicon nitride matrix composites were fabricated using slurry impregnation and cyclic infiltration with colloidal silica sol. The microstructure and fracture surface were characterized by SEM, the mechanical behavior was investigated by three-point bending test, and the dielectric constant was also measured by impedance analysis. The microstructure showed that the fiber and the matrix had a physical bonding, forming a clearance interface. The mechanical behavior suggested that the porous matrix acted as crack deflection, and the fracture surface had a lot of fiber pull-out. However, the interlaminar shear strength was not so good. The dielectric constant of the composites at room temperature was about 2.8-3.1. The relatively low dielectric constant and non-catastrophic failure indicated the potential application in the radome materials field.
2008, vol. 15, no. 1, pp.
62-66.
https://doi.org/10.1016/S1005-8850(08)60013-4
Abstract:
A particle preform was designed and prepared by conglomerating and cold-pressed process, which was condensed by chemical vapor infiltration (CVI) process to fabricate silicon nitride particles reinforced silicon nitride composites. The conglomerations are of almost sphericity after conglomerated. There are large pores among the conglomerations and small pores within themselves in the preform according to the design and the test of pore size distribution. The pore size of the preform is characterized by a double-peak distribution. The pore size distribution is influenced by conglomeration size. Large pores among the conglomerations still exist after infiltrated Si3N4 matrix. The conglomerations, however, are very compact. The CVI Si3N4 looks like cauliflowershaped structure.
A particle preform was designed and prepared by conglomerating and cold-pressed process, which was condensed by chemical vapor infiltration (CVI) process to fabricate silicon nitride particles reinforced silicon nitride composites. The conglomerations are of almost sphericity after conglomerated. There are large pores among the conglomerations and small pores within themselves in the preform according to the design and the test of pore size distribution. The pore size of the preform is characterized by a double-peak distribution. The pore size distribution is influenced by conglomeration size. Large pores among the conglomerations still exist after infiltrated Si3N4 matrix. The conglomerations, however, are very compact. The CVI Si3N4 looks like cauliflowershaped structure.
2008, vol. 15, no. 1, pp.
67-73.
https://doi.org/10.1016/S1005-8850(08)60014-6
Abstract:
Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS (acrylonitrile-butadiene-styrene copolymer) composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate (BA) and styrene (St). The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment.
Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS (acrylonitrile-butadiene-styrene copolymer) composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate (BA) and styrene (St). The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment.
2008, vol. 15, no. 1, pp.
74-78.
https://doi.org/10.1016/S1005-8850(08)60015-8
Abstract:
LiMn2O4 powder as a cathode materials for rechargeable lithium-ion batteries was prepared by solid-state reaction from LitCO3 and electrolytic MnO2 at different sintering periods (2, 6, 18, and 32 h). X-ray diffraction (XRD) patterns of the prepared samples are identified as the spinel structure with a space group of Fd3m. The lattice parameters almost remain the same as the sintering periods increase. The sample with a sintering period of 32 h shows good cycling performance at both low and nigh current densities, and also elevated temperature. It is believed that the excellent electrochemical behavior of this sample results from its good crystallinity and large grain size compared with other samples. Different electrochemical measurements were conducted to investigate the electrochemical properties of spinel LiMn204.
LiMn2O4 powder as a cathode materials for rechargeable lithium-ion batteries was prepared by solid-state reaction from LitCO3 and electrolytic MnO2 at different sintering periods (2, 6, 18, and 32 h). X-ray diffraction (XRD) patterns of the prepared samples are identified as the spinel structure with a space group of Fd3m. The lattice parameters almost remain the same as the sintering periods increase. The sample with a sintering period of 32 h shows good cycling performance at both low and nigh current densities, and also elevated temperature. It is believed that the excellent electrochemical behavior of this sample results from its good crystallinity and large grain size compared with other samples. Different electrochemical measurements were conducted to investigate the electrochemical properties of spinel LiMn204.
2008, vol. 15, no. 1, pp.
79-83.
https://doi.org/10.1016/S1005-8850(08)60016-X
Abstract:
The ion selectivity of electrodeposited nickel hexacyanoferrate (NiHCF) thin films was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). NiHCF thin films were prepared by cathodic deposition on Pt and Al substrates. EIS and CV curves were determined in 1 mol/L (KNO3+C5NO3) and 1 mol/L (NaNO3+CsNO3) mixture solutions, which were sensitive to the concentration of Cs+ in the electrolytes. Experimental results show that all Nyquist impedance plots show depressed semicircles in the high-frequency range changing over into straight lines at lower frequencies. With increasing amounts of Cs+, the redox potentials in CV curves shift toward more positive values and the redox peaks broaden; the semicircle radius in corresponding EIS curves and the charge transfer resistance also increase. EIS combining CV is able to provide valuable insights into the ion selectivity of NiHCF thin films.
The ion selectivity of electrodeposited nickel hexacyanoferrate (NiHCF) thin films was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). NiHCF thin films were prepared by cathodic deposition on Pt and Al substrates. EIS and CV curves were determined in 1 mol/L (KNO3+C5NO3) and 1 mol/L (NaNO3+CsNO3) mixture solutions, which were sensitive to the concentration of Cs+ in the electrolytes. Experimental results show that all Nyquist impedance plots show depressed semicircles in the high-frequency range changing over into straight lines at lower frequencies. With increasing amounts of Cs+, the redox potentials in CV curves shift toward more positive values and the redox peaks broaden; the semicircle radius in corresponding EIS curves and the charge transfer resistance also increase. EIS combining CV is able to provide valuable insights into the ion selectivity of NiHCF thin films.
2008, vol. 15, no. 1, pp.
84-90.
https://doi.org/10.1016/S1005-8850(08)60017-1
Abstract:
Compared with conventional electric power generation systems, the solid oxide fuel cell (SOFC) has many advantages because of its unique features. High temperature SOFC has been successfully developed to its commercial applications, but it still faces many problems which hamper large-scale commercial applications of SOFC. To reduce the cost of SOFC, intermediate temperature solid oxide fuel cell (IT-SOFC) is presently under rapid development. The status of IT-SOFC was reviewed with emphasis on discussion of their component materials.
Compared with conventional electric power generation systems, the solid oxide fuel cell (SOFC) has many advantages because of its unique features. High temperature SOFC has been successfully developed to its commercial applications, but it still faces many problems which hamper large-scale commercial applications of SOFC. To reduce the cost of SOFC, intermediate temperature solid oxide fuel cell (IT-SOFC) is presently under rapid development. The status of IT-SOFC was reviewed with emphasis on discussion of their component materials.
2008, vol. 15, no. 1, pp.
91-95.
https://doi.org/10.1016/S1005-8850(08)60018-3
Abstract:
The elasticity deformation of rolls was analyzed by means of two-dimensional finite element method (FEM) with variable thickness. Three typical mills were used as objects for analysis. A thorough study was done on the control capabilities of these mills on the strip shape. Then the strip shape control capabilities of the three mills was compared synthetically.
The elasticity deformation of rolls was analyzed by means of two-dimensional finite element method (FEM) with variable thickness. Three typical mills were used as objects for analysis. A thorough study was done on the control capabilities of these mills on the strip shape. Then the strip shape control capabilities of the three mills was compared synthetically.
Submit Manuscript
E-mail alert
RSS
