An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical ...An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.展开更多
The components of the equipment for processing the Al melts into the molded parts can be markedly corroded by the molten Al. In this study, a 4 μm CrN coating or CrN/TiN multilayer coating for providing the physical ...The components of the equipment for processing the Al melts into the molded parts can be markedly corroded by the molten Al. In this study, a 4 μm CrN coating or CrN/TiN multilayer coating for providing the physical and chemical barriers between the molten reactive Al and the steel substrate were deposited by Cathodic Arc Evaporation onto 10 mm-thick heat-resistant steel plates. The dipping tests were conducted in a 700℃ A356 melt for 1 to 21 h at intervals of 3 h. The damage of the coated steel was eva...展开更多
Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied...Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.展开更多
Removal of inclusions from industrial pure molten aluminum(A01) by stirring active molten flux was studied. Wettability of nonmetallic inclusions in the molten aluminum was worse than that in active molten flux. Accor...Removal of inclusions from industrial pure molten aluminum(A01) by stirring active molten flux was studied. Wettability of nonmetallic inclusions in the molten aluminum was worse than that in active molten flux. According to the surface renewal model, the inclusions were easily transferred into molten active flux from fine aluminum droplets and then reacted chemically when molten aluminum was dispersed into fine aluminum droplets in stirring active molten flux. Tensile tests show that tensile strength of purified tensile sample(as-cast) increases by 8.59%. SEM photographs show that the fracture cracks of purified tensile sample are homogeneous, and the dimples are small and homogeneous. From metallographs and statistic results of Leco analysis software, it is found that the quantities and sizes of the inclusions in purified sample are obviously fewer and smaller than in unpurified tensile sample(as-cast).展开更多
The injection of nitrogen in molten aluminum through a static impeller in a tank degassing unit is studied. Using basic principles of fluid mechanics, it is analyzed the influence of the nozzle diameter on the bubble ...The injection of nitrogen in molten aluminum through a static impeller in a tank degassing unit is studied. Using basic principles of fluid mechanics, it is analyzed the influence of the nozzle diameter on the bubble diameter and the mean residence time of the bubbles in the molten aluminum. By means of transient isothermal 2D Computational Fluid Dynamics (CFD) simulations, the influence of the nitrogen volumetric flow rate on the phase distributions and the tank degasser dynamics is studied. Finally, an adiabatic CFD simulation is carried out in order to elucidate the changes in the molten aluminum temperature due to the injection of nitrogen at ambient temperature. This simulation shows that molten aluminum does not suffer drastic temperature reductions given that, in spite?that?the nitrogen is fed at ambient temperature, the mass of nitrogen is relatively small compared with the mass of aluminum.展开更多
Corrosion resistance of ceramic substrate glazes to molten aluminum was studied in this paper. The glazes can spread slightly in aluminum alloy according to SEM examination of solidified interface between the glazes a...Corrosion resistance of ceramic substrate glazes to molten aluminum was studied in this paper. The glazes can spread slightly in aluminum alloy according to SEM examination of solidified interface between the glazes and aluminum alloy. The components of B2O3-P2O5 glazes were not detected with electron probe at the side of aluminum alloy near the interface, but the components of boron-free glaze were detected. It is shown that borophosphate glazes can resist the corrosion of molten aluminum.展开更多
The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is cause...The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is caused by Li^+ inserting into the vacancies of octahedral or tetrahedral structure of 0 atom skeleton in у-Al_2O_3 . The strength of oxide film decreases as the crytallinity increases by the treating of flux containing LiF.展开更多
Molten aluminum (A001) was filtered by using ceramic foam filters coated with active enamel. Tensile test shows that the elongation of filtered sample is increased by 15.5%, but the tensile strength of the sample is a...Molten aluminum (A001) was filtered by using ceramic foam filters coated with active enamel. Tensile test shows that the elongation of filtered sample is increased by 15.5%, but the tensile strength of the sample is almost the same as that of unfiltered one. The fracture cracks and dimples of filtered sample are fine and homogeneous according to SEM examination. In addition, metallographic observation shows that the filtered sample has very few inclusions of approximately 8 μm in diameter, but the unfiltered sample has some inclusions of approximately 60 μm in length and 20 μm in width. However, it is suggested that the active enamel coat can effectively capture the inclusions and dissolve them during filtering molten aluminum.展开更多
An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of sp...An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of specific conductivity, density and kinetic viscosity of molten salt with mole ratio o f MeEtlmCl/A1lCl3/LiAlCl4 were observed. A solubility maximum of LiAlCl4 with 5 4% in molar fraction was shown at a mole ratio of AlCl43/MeEtlmCl = 1 .2. An increase in density and viscosity, and a decrease in specific conductivity were found with increasing the concentrations of LiAlCl4 and AlCl3. The dependence of specific conductivity of this acid molten salt upon temperature was found to display Vogel-Tammanm-Fucher behavior. However, Arrhenius behavior was observed at two special mole ratios of MeEtImCl/AlCl3/LiAlCl4 = 1:1.5:0.05 and 1. 1.5:0. 10. The conductivity equations of this molten salt at various compositions were constructed. The ion interaction in the acid molten salt was studied using 7Li and 27Al nuclear magnetic resonance spectroscopic methods. The effect of concentrations of LiAlCl4 and AlCl3 on the ion interaction was also discussed.展开更多
针对6061铝合金的电子束选区熔化(Selective Electron Beam Melting,SEBM)过程,采用ANSYS构建了温度场仿真三维有限元模型。考虑材料的热物性参数随温度的变化特性,通过高斯面热源在粉末床上移动,研究了电子束功率、扫描速度和铝合金预...针对6061铝合金的电子束选区熔化(Selective Electron Beam Melting,SEBM)过程,采用ANSYS构建了温度场仿真三维有限元模型。考虑材料的热物性参数随温度的变化特性,通过高斯面热源在粉末床上移动,研究了电子束功率、扫描速度和铝合金预热温度对熔池尺寸、熔池热历史的影响,为6061铝合金电子束选区增材制造工艺参数的选择提供理论依据。研究结果表明:熔池宽度、熔池深度随着电子束功率、预热温度的增大而增大;输入线能量小于0.19 J/mm时,熔池深度、宽度均随着扫描速度的增大而减小,熔池长度随扫描速度的增大而增大;当输入线能量大于0.19 J/mm时,熔池深度、宽度均随着扫描速度的增大而增大,但增大速率减小,熔池长度随扫描速度的增大而减小。电子束功率是影响熔池冷却速率的主要因素。不同扫描路径的粉末层温度分布不同,采用合理的扫描路径可使得整个零件的热分布更加均匀。展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51272208)the Program for New Century Excellent Talents in University (NCET–12–0454)the Program for Young Excellent Talents in Shaanxi Province, China (2013KJXX–50)
文摘An FeMo-alloy-doped β-SiA1ON （FeMo/β-SiA1ON） composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, A1N, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investi- gated. Some properties of the composite, including its bending strength at 700℃ and after oxidization at 700℃ for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion re- sistance to molten aluminum is maintained. These findings indicate that the developed FeMo/β-SiA1ON composite exhibits strong potential for application to molten aluminum environments.
文摘The components of the equipment for processing the Al melts into the molded parts can be markedly corroded by the molten Al. In this study, a 4 μm CrN coating or CrN/TiN multilayer coating for providing the physical and chemical barriers between the molten reactive Al and the steel substrate were deposited by Cathodic Arc Evaporation onto 10 mm-thick heat-resistant steel plates. The dipping tests were conducted in a 700℃ A356 melt for 1 to 21 h at intervals of 3 h. The damage of the coated steel was eva...
文摘Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.
文摘Removal of inclusions from industrial pure molten aluminum(A01) by stirring active molten flux was studied. Wettability of nonmetallic inclusions in the molten aluminum was worse than that in active molten flux. According to the surface renewal model, the inclusions were easily transferred into molten active flux from fine aluminum droplets and then reacted chemically when molten aluminum was dispersed into fine aluminum droplets in stirring active molten flux. Tensile tests show that tensile strength of purified tensile sample(as-cast) increases by 8.59%. SEM photographs show that the fracture cracks of purified tensile sample are homogeneous, and the dimples are small and homogeneous. From metallographs and statistic results of Leco analysis software, it is found that the quantities and sizes of the inclusions in purified sample are obviously fewer and smaller than in unpurified tensile sample(as-cast).
文摘The injection of nitrogen in molten aluminum through a static impeller in a tank degassing unit is studied. Using basic principles of fluid mechanics, it is analyzed the influence of the nozzle diameter on the bubble diameter and the mean residence time of the bubbles in the molten aluminum. By means of transient isothermal 2D Computational Fluid Dynamics (CFD) simulations, the influence of the nitrogen volumetric flow rate on the phase distributions and the tank degasser dynamics is studied. Finally, an adiabatic CFD simulation is carried out in order to elucidate the changes in the molten aluminum temperature due to the injection of nitrogen at ambient temperature. This simulation shows that molten aluminum does not suffer drastic temperature reductions given that, in spite?that?the nitrogen is fed at ambient temperature, the mass of nitrogen is relatively small compared with the mass of aluminum.
基金supported by the National Key Fundamental Research Project(973)(Project G1999064900).
文摘Corrosion resistance of ceramic substrate glazes to molten aluminum was studied in this paper. The glazes can spread slightly in aluminum alloy according to SEM examination of solidified interface between the glazes and aluminum alloy. The components of B2O3-P2O5 glazes were not detected with electron probe at the side of aluminum alloy near the interface, but the components of boron-free glaze were detected. It is shown that borophosphate glazes can resist the corrosion of molten aluminum.
文摘The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is caused by Li^+ inserting into the vacancies of octahedral or tetrahedral structure of 0 atom skeleton in у-Al_2O_3 . The strength of oxide film decreases as the crytallinity increases by the treating of flux containing LiF.
文摘Molten aluminum (A001) was filtered by using ceramic foam filters coated with active enamel. Tensile test shows that the elongation of filtered sample is increased by 15.5%, but the tensile strength of the sample is almost the same as that of unfiltered one. The fracture cracks and dimples of filtered sample are fine and homogeneous according to SEM examination. In addition, metallographic observation shows that the filtered sample has very few inclusions of approximately 8 μm in diameter, but the unfiltered sample has some inclusions of approximately 60 μm in length and 20 μm in width. However, it is suggested that the active enamel coat can effectively capture the inclusions and dissolve them during filtering molten aluminum.
文摘An acid molten salt was formed by means of mixing 1 -methyl- 3 -ethylimidazolium chloride with AlCl3 and LiAlCl4 at ambient temperature. The solubility of LiAlCl4 in the acid molten salt was measured. Variations of specific conductivity, density and kinetic viscosity of molten salt with mole ratio o f MeEtlmCl/A1lCl3/LiAlCl4 were observed. A solubility maximum of LiAlCl4 with 5 4% in molar fraction was shown at a mole ratio of AlCl43/MeEtlmCl = 1 .2. An increase in density and viscosity, and a decrease in specific conductivity were found with increasing the concentrations of LiAlCl4 and AlCl3. The dependence of specific conductivity of this acid molten salt upon temperature was found to display Vogel-Tammanm-Fucher behavior. However, Arrhenius behavior was observed at two special mole ratios of MeEtImCl/AlCl3/LiAlCl4 = 1:1.5:0.05 and 1. 1.5:0. 10. The conductivity equations of this molten salt at various compositions were constructed. The ion interaction in the acid molten salt was studied using 7Li and 27Al nuclear magnetic resonance spectroscopic methods. The effect of concentrations of LiAlCl4 and AlCl3 on the ion interaction was also discussed.
