论文部分内容阅读
Recently,atomic layer deposition(ALD)has been adopted in the surface modifications of nanoparticles with controllable dense and uniform nanoscale coating.Up to now,several kinds of equipment designs,including static particle bed reactors,fluidized bed reactors,and rotary reactors have been investigated.[1-2] Though having been extensively used to obtain uniform and dense coatings,the limitation of precursor transport or nonuniformity of particle dispersion would go against the improvements of coating speed and precursor usage.Since a large amount of precursors are required during coating due to their large specific surface area,the coating speed and precursor utilization are important factors for practical use of this ALD approach.Here our rotating fluidized bed ALD reactor for nanoparticles coating will be introduced with process study.[3] Continuous fluidization enlarges the void space in the particle bed,while rotation enhances the gas-solid interactions to stabilize fluidization state.The precursor transport is facilitated by intense gas-solid mass transfer under the conditions of high rotation speed and corresponding minimum fluidizing velocity.In situ mass spectroscopic detection of the reaction progress is adopted to minimize the process time and increase precursor usage.The coating speed is found to increase with larger precursor supply rate,while a close to full usage of precursors is finally achieved by increasing the thickness of the annular particle bed.The exploration would be instructive for surface modifications using ALD technique,especially for large quantities of nanoparticles in practical use.