FABRICATION OF NANOWIRES AND HIERARCHICALLY POROUS MATERIALS THROUGH SUPERCRITICAL CO2 ASSISTED NEBULIZATION

摘要

A processing technique for creating nanowires and hierarchically porous micro/nano structures of ceramic materials is provided. The process includes evaporation of micron-sized water droplets containing dissolved organic salts on heated substrates followed by thermal decomposition of the deposited material. The micron-sized droplets may be generated by supercritical CO2 assisted nebulization, in which high-pressure streams of aqueous solution and supercritical CO2 are mixed, followed by controlled depressurization through a fine capillary. Rapid evaporation takes place on the heated substrates and structures are generated due to CO2 effervescence from the droplets and evaporation of water, along with the pinning of the three phase contact line. Depending on the mass deposited, a mesh of nano-wires or membrane-like structures may result. Sintering of the membrane-like scaffolds above the decomposition temperature of the organic salt creates nanopores within the structures, creating a dual hierarchy of pores.

主权项

1. A process comprising:
mixing a stream of supercritical CO2 with an aqueous solution of an organic salt in a continuous flow operation; creating an aerosol from the mixture; and depositing the aerosol on heated substrates.