Silicon Chemical Vapor Deposition on macro and submicron powders in a fluidized bed

Titanium oxide (TiO2) submicron powders have been treated by Chemical Vapor Deposition (CVD) in a vibro-fluidized bed in order to deposit silicon layers of nanometer scale on each individual grain from silane (SiH4). Experimental results show that for the conditions tested, the original granular structure of the powders is preserved for 90% of the initial bed weight while the remaining 10% consists of agglomerates in millimetre range found near the distributor of the reactor. A comparison between experimental and modelling results using the MFIX code shows that for Geldart's Group B alumina particles (Al2O3), the model represents both the bed hydrodynamics and silane conversion rates quite well. The future objective is to extend the simulation capability to cohesive submicron powders in order to achieve better predictability of the phenomena governing ultrafine particles.

First, TiO2 submicron powders have been treated by Chemical Vapor Deposition in a vibro-fluidized bed allowing to deposit silicon nanodots on individual grains from silane (SiH4). Then, a comparison between experimental and modelling results using the MFIX code shows that for easy-to-fluidize Al2O3 particles, the model represents both the bed hydrodynamics and silane conversion rates quite well.Figure optionsDownload as PowerPoint slide