Study And Application Of Micro-nano Powder Atomic Layer Deposition Equipment Via Ultrasonic Vibration

Micro-nano powder materials,with a great many of unique properties in thermal,optical,acoustic,electrical,and chemical compared with the bulk macro materials deriving from their small size effect,have been extensively applied in the fields of new energy,medical biology,aerospace,environmental catalysis and luminous display,however,they tend to agglomerate with high surface activity on account of the surface and interface effects,hindering their application seriously.Therefore,it is necessary to perform surface modification and coating modification to overcome its agglomeration phenomenon and enhance their performance in various aspects.Atomic layer deposition(ALD),a special chemical vapor deposition technology with the characteristics of self-limiting growth,excellent three-dimensional conformality,uniform deposition films,and precise film thickness control,has been widely put into use in surface modification and interface control.In this dissertation,a self-designed ultrasonic vibration powder ALD equipment for the micro-nano powder materials is adopted to improve their dispersion during the process of ALD,and uniform coating of micro-nano powders has been achieved with increasing deposition efficiency and batch throughput capacity.In addition,the surface modification of organic pigments and phosphors has been explored via this equipment,which lays the foundation of ALD technique in the industrial application.The main research work can be described as followed:(1)The external force field of ultrasonic vibration is integrated into the ALD equipment,and the dispersion effect of ultrasonic vibration is verified via the experiments.Aiming at the defects such as the tendency to agglomerate for the micro-nano powders in the ALD process and the low precursors utilization,the multiphysics coupling is proposed to realize the better dispersion of the micro-nano powders,which overcomes their agglomeration and improves the film deposition uniformity,efficiency,and production rate.The equipment has been built,the Al₂O₃ film deposition on the surface of SiO₂ nanoparticles are performed to f verify the feasibility of the design.(2)Surface modification of nanoparticles organic pigments Permanent Violet has been achieved via the above-mentioned self-designed ultrasonic vibration ALD equipment for powders,and the stabilized mechanism have also been investigated.The surface of the organic pigment Permanent Violet is coated with Al₂O₃ film to realize the dispersion stability in organic solvent and overcome its agglomeration.The stabilization mechanism has been analyzed via Zeta potential test.The coated Al₂O₃ film on the surface of Permanent Violet forms an electric double layers,generating the repulsive force to reduce the attractive force between the Permanent Violet nanoparticles,which result in the dispersion stability of the pigments in organic solvent,which is of great significance for the practical application of organic pigments in high-quality image display.(3)Surface modification of micro-sized silicon-based nitride phosphors has been obtained by the ultrasonic vibration powder fluidization ALD technique.Al₂O₃ film is coated on the surface of the phosphors to enhance their thermal stability and better their optical properties.The thermal stability of the phosphors at 600 ? can be increased by 26.5%,which solves the problem of large color temperature drift on the phosphors appeared in the fabrication of the LED device,laying great foundation on the preparation of high-powered LED devices with high luminous efficiency and excellent color rendering.