A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. Thi...A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. This evaluation was performed for improving and controlling the film qualities and the productivities, using two quartz crystal microbalances (QCM) installed at the </span><span style="font-family:Verdana;">inlet and exhaust of the chamber by taking into account that the QCM frequency corresponds to the real time changes in the gas properties.</span><span style="font-family:Verdana;"> Typically, the time period approaching from the inlet to the exhaust was shorter for the trichlorosilane gas than that for the dichlorosilane gas. The trichlorosilane gas was shown to move like plug flow, while the dichlorosilane gas seemed to be well mixed in the entire chamber.展开更多
In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catal...In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition（CCVD）of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.展开更多
A mathematical model to represent the fluid flow, temperature distribution and mass transfer in CVD reactors has been developed. The model is used to predict the velocity, temperature, and molar concentration profiles...A mathematical model to represent the fluid flow, temperature distribution and mass transfer in CVD reactors has been developed. The model is used to predict the velocity, temperature, and molar concentration profiles in the tapered annulus of a reactor for silicon deposition from SiCl_4 in H_2. Results of the investigation contribute to the understanding of the transport pro- cesses involved in such a system. The model can also be used for optimizing the design parameters, such as inlet flow rate, susceptor tilt angle, etc.展开更多
The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008.In this paper,we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficientl...The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008.In this paper,we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficiently. The 2-D relative neutron intensity profiles for the water-vapor two-phase flow inside the robe were obtained using the MCNP code without influence of y-ray and electronic-noise.The MCNP simulation of the 2-D neutron intensity profile for the water-vapor two-phase flow was demonstrated.The simulated 2-D neutron intensity profiles could be used as the benchmark data base by calibrating part of the data measured by the CARR-NRI.The 3-D objective images allow us to understand the flow pattern more clearly and it is reconstructed using the MATLAB through the threshold transformation techniques.And thus it is concluded that the MCNP code and the MATLAB are very useful for constructing the benchmark data base for the investigation of the water-vapor two-phase flow using the CARR-NRI.展开更多
文摘A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. This evaluation was performed for improving and controlling the film qualities and the productivities, using two quartz crystal microbalances (QCM) installed at the </span><span style="font-family:Verdana;">inlet and exhaust of the chamber by taking into account that the QCM frequency corresponds to the real time changes in the gas properties.</span><span style="font-family:Verdana;"> Typically, the time period approaching from the inlet to the exhaust was shorter for the trichlorosilane gas than that for the dichlorosilane gas. The trichlorosilane gas was shown to move like plug flow, while the dichlorosilane gas seemed to be well mixed in the entire chamber.
文摘In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition（CCVD）of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.
文摘A mathematical model to represent the fluid flow, temperature distribution and mass transfer in CVD reactors has been developed. The model is used to predict the velocity, temperature, and molar concentration profiles in the tapered annulus of a reactor for silicon deposition from SiCl_4 in H_2. Results of the investigation contribute to the understanding of the transport pro- cesses involved in such a system. The model can also be used for optimizing the design parameters, such as inlet flow rate, susceptor tilt angle, etc.
基金Supported by National Natural Science Foundation of China (Grant No.50876080)
文摘The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008.In this paper,we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficiently. The 2-D relative neutron intensity profiles for the water-vapor two-phase flow inside the robe were obtained using the MCNP code without influence of y-ray and electronic-noise.The MCNP simulation of the 2-D neutron intensity profile for the water-vapor two-phase flow was demonstrated.The simulated 2-D neutron intensity profiles could be used as the benchmark data base by calibrating part of the data measured by the CARR-NRI.The 3-D objective images allow us to understand the flow pattern more clearly and it is reconstructed using the MATLAB through the threshold transformation techniques.And thus it is concluded that the MCNP code and the MATLAB are very useful for constructing the benchmark data base for the investigation of the water-vapor two-phase flow using the CARR-NRI.
