The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were char...The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by transmission electron microscopy （TEM）, BET equation, X-ray diffraction （XRD）, and the corresponding selected area electron diffraction （SAED）. The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate （AP） was investigated by differential thermal analyzer （DTA）. Compared with the thermal decomposition of pure AP, the addition of Co nanoparticles （2%-10%, by mass） decreases the decomposition temperature of AP by 145.01-155.72℃. Compared with Co3O4 nano-particles and microsized Co particles, the catalytic effect of Co nanoparticles for AP is stronger. Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases. The present work provides useful information for the application of Co nanoparficles in the AP-based propellant.展开更多
A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure ...A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure on the formation of LiFePO4/C particles were investigated. Results showed that the pH value was the key factot on the formation of phase pure LiFePO4, which only formed at pH = 7; the LiFePO4/C-occurred as particles with about 70-200 nm size and LiFePO4 was covered by a thin carbon layer; higher flow rate, higher pressure, and lower temperature led to smaller particles of LiFePO4/C.展开更多
Microstructural stability of IN939 superalloy with two different manufacturing routes was investigated during long-term aging at elevated temperatures by light optical microscope（OM） and scanning electron microscope...Microstructural stability of IN939 superalloy with two different manufacturing routes was investigated during long-term aging at elevated temperatures by light optical microscope（OM） and scanning electron microscope（SEM） equipped with an EDS system.The results show mat the coarsening behavior of γ＇ particles is primarily impacted by the initial heat treatment conditions,and the effect of the prior manufacturing route（casting or hot forming） is found to be insignificant,if any,on the γ＇ particles coarsening kinetics.In the temperature range of 790-827 ℃,IN939 cast/wrought-HT2 alloys have more microstructural stability,while in the temperature range of 827-910 ℃,the initial heat treatment marked as HT1 provides more stable microstructure for the cast or wrought IN939 superalloy.展开更多
A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction （MOR） without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cle...A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction （MOR） without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes （MWC- NTs） from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential （ca. 0.9 V vs. RHE） reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.展开更多
CNTs with core-shell structure were successfully synthesized by a microwave-assisted polyol method,and magnetic Ni nanoparticles were employed as a catalyst. The preparation method is fast and simple. The structures,m...CNTs with core-shell structure were successfully synthesized by a microwave-assisted polyol method,and magnetic Ni nanoparticles were employed as a catalyst. The preparation method is fast and simple. The structures,morphology and magnetic properties of the as-synthesized samples were investigated using Raman spectrometer,X-ray diffraction (XRD),transmission electron microscopy (TEM),vibrating sample magnetometer (VSM),respectively. The XRD results suggested that Ni particles used as a catalyst in our experiment were nano-sized. In this paper,magnetic Ni nanoparticles were employed as a catalyst,and an electric spark on metal Ni nanoparticles with the microwave eddy current effect could induce CNTs’ formation with the further reaction. The length of hollow carbon nanotubes was micro-sized and the diameters of most of the CNTs were varying from 18 to 20 nm according to the TEM images. Magnetic measurements demonstrated that CNTs with core-shell structure indicated a characteristic ferromagnetic behavior compared with Ni nanoparticles.展开更多
基金Supported by the National Natural Science Foundation of China （50306008, 50602024）.
文摘The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by transmission electron microscopy （TEM）, BET equation, X-ray diffraction （XRD）, and the corresponding selected area electron diffraction （SAED）. The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate （AP） was investigated by differential thermal analyzer （DTA）. Compared with the thermal decomposition of pure AP, the addition of Co nanoparticles （2%-10%, by mass） decreases the decomposition temperature of AP by 145.01-155.72℃. Compared with Co3O4 nano-particles and microsized Co particles, the catalytic effect of Co nanoparticles for AP is stronger. Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases. The present work provides useful information for the application of Co nanoparficles in the AP-based propellant.
基金Supported by Shanghai Special Foundation on Nanomaterials (0243nm305)
文摘A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure on the formation of LiFePO4/C particles were investigated. Results showed that the pH value was the key factot on the formation of phase pure LiFePO4, which only formed at pH = 7; the LiFePO4/C-occurred as particles with about 70-200 nm size and LiFePO4 was covered by a thin carbon layer; higher flow rate, higher pressure, and lower temperature led to smaller particles of LiFePO4/C.
文摘Microstructural stability of IN939 superalloy with two different manufacturing routes was investigated during long-term aging at elevated temperatures by light optical microscope（OM） and scanning electron microscope（SEM） equipped with an EDS system.The results show mat the coarsening behavior of γ＇ particles is primarily impacted by the initial heat treatment conditions,and the effect of the prior manufacturing route（casting or hot forming） is found to be insignificant,if any,on the γ＇ particles coarsening kinetics.In the temperature range of 790-827 ℃,IN939 cast/wrought-HT2 alloys have more microstructural stability,while in the temperature range of 827-910 ℃,the initial heat treatment marked as HT1 provides more stable microstructure for the cast or wrought IN939 superalloy.
基金ACKNOWLEDGEMENTS This work was supported by the National Natural Science Foundation of China （No.21273215）, National Instrumentation Program （No.2011YQ03012416）, and 973 Program from the Ministry of Science and Technology of China （No.2010CB923302）.
文摘A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction （MOR） without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes （MWC- NTs） from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential （ca. 0.9 V vs. RHE） reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos.50672001,51072002)the "211" Project of Anhui University
文摘CNTs with core-shell structure were successfully synthesized by a microwave-assisted polyol method,and magnetic Ni nanoparticles were employed as a catalyst. The preparation method is fast and simple. The structures,morphology and magnetic properties of the as-synthesized samples were investigated using Raman spectrometer,X-ray diffraction (XRD),transmission electron microscopy (TEM),vibrating sample magnetometer (VSM),respectively. The XRD results suggested that Ni particles used as a catalyst in our experiment were nano-sized. In this paper,magnetic Ni nanoparticles were employed as a catalyst,and an electric spark on metal Ni nanoparticles with the microwave eddy current effect could induce CNTs’ formation with the further reaction. The length of hollow carbon nanotubes was micro-sized and the diameters of most of the CNTs were varying from 18 to 20 nm according to the TEM images. Magnetic measurements demonstrated that CNTs with core-shell structure indicated a characteristic ferromagnetic behavior compared with Ni nanoparticles.
