The effects of gravity on nickel electrodeposition,the morphology and mechanical properties of deposits were studied in a super gravity field.Predictions in a microgravity field were also presented based on the obtain...The effects of gravity on nickel electrodeposition,the morphology and mechanical properties of deposits were studied in a super gravity field.Predictions in a microgravity field were also presented based on the obtained experimental tendency.Linear sweep voltammetry reveals that the nickel electrodeposition process is enhanced by increasing the gravity coefficient（G）.The limiting current density changes from 10.2 to 293.0 mA·cm-2 with the increase of the G value from 10-4 to 354.The morphology of deposits was analyzed by scanning electron microscopy（SEM） and atomic force microscopy（AFM）.The images show that the morphology deposited in the super gravity field has finer grain sizes and denser and smoother surfaces.The roughness reduces from 48.3 to 4.9 nm with the increase of the G value from 10-4 to 354.Meanwhile,mechanical tests indicate that the mechanical properties of nickel foils are greatly improved due to introducing a super gravity field during electrodeposition.展开更多
Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully ...Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr～ 400 and tan δ 〈 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.展开更多
Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulp...Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.展开更多
The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile...The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.展开更多
基金supported by the National Natural Science Foundation of China(Nos.50804043,50674011)the Major Programs on the Equipment Development of Chinese Academy of Sciences(No.YZ0618)
文摘The effects of gravity on nickel electrodeposition,the morphology and mechanical properties of deposits were studied in a super gravity field.Predictions in a microgravity field were also presented based on the obtained experimental tendency.Linear sweep voltammetry reveals that the nickel electrodeposition process is enhanced by increasing the gravity coefficient（G）.The limiting current density changes from 10.2 to 293.0 mA·cm-2 with the increase of the G value from 10-4 to 354.The morphology of deposits was analyzed by scanning electron microscopy（SEM） and atomic force microscopy（AFM）.The images show that the morphology deposited in the super gravity field has finer grain sizes and denser and smoother surfaces.The roughness reduces from 48.3 to 4.9 nm with the increase of the G value from 10-4 to 354.Meanwhile,mechanical tests indicate that the mechanical properties of nickel foils are greatly improved due to introducing a super gravity field during electrodeposition.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11028409 and 60976061)the Fundamental Research Funds for the Central Universities of China (Grant No. ZYGX2009Z0001)
文摘Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr～ 400 and tan δ 〈 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.
文摘Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.
文摘The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.
