Electrospray Flame Synthesis of Yttria-Stabilized Zirconia Nanoparticles

Abstract

In this study, the technological feasibility of an electrospray-based flame synthesis process for the production of thin films of nanosized metal oxide particulates was investigated. On the basis of published results on electro-hydrodynamic atomization, a spray system was designed, implemented, and tested. Initial tests focused on synthesis of yttria-stabilized zirconia (YSZ) particulates, and the results showed that aggregates with quasi-monodisperse primary particle sizes below 100 nm with cubic-fluorite crystal phase composition can be manufactured through this production route. These tests utilized organometallic solutions of Zr-n-propoxide and Y-2-methoxyethoxide in a mixture of n-propanol and 2-methoxyethanol, which were electrosprayed into the postflame flow of a multielement diffusion burner. Both theoretical analysis and experimental evidence indicate that controlled synthesis of particulate with narrow particle size distribution is feasible. The radial arrangement of electrospray emitters chosen for the initial experiments appears to be a promising spray configuration for further development.

Flame aerosol synthesis of nanostructured materials and functional devices: Processing, modeling, and diagnostics

“…Electro-hydrodynamic (EHD) atomization, i.e. electrospray atomizer, which is capable of generating monodisperse aerosols with much smaller droplets than any other spray methods, may possibly meet the need of controlling sizes or dispersity with sufficient accuracy [195][332]- [334].…”

“…The electric charges on the droplets result in repulsive forces that delay cloud coalescence, which, combined with the Rayleigh jet break-up into quasi-monodisperse droplets, enables the atomizer to be attractive in nanomaterial synthesis [195][335] [336]. More recently, Geier and Parker [195] employed an electrospray atomizer in flame synthesis of yttria-stabilized zirconia (YSZ) nanoparticles. create a vertically-directed hot gas flow for combustion of the generated droplets [195].…”

“…More recently, Geier and Parker [195] employed an electrospray atomizer in flame synthesis of yttria-stabilized zirconia (YSZ) nanoparticles. create a vertically-directed hot gas flow for combustion of the generated droplets [195]. Despite the controllably narrow particle size distribution of nanoparticles by electrospray flame synthesis, the small production rates limit the applicability of the process for mass quantities.…”

“…oxygen, along with its location in a cylindrical reactor chamber [329]; (B) Large-scale novel atomization combining a pressure swirl nozzle (liquid hollow cone nozzle) and a dispersion gas nozzle, where α is the gas inclination angle, β is the gas swirl angle and γ is the for liquid hollow cone angle [331]; (C) Lab-scale electrospray atomizer [195]. (Reprinted with permission from literature [195][329] [331]). When the residence time is much smaller than the chemical reaction time, vapor deposits on the plate and forms the dense smooth film which corresponed to "chemical vapor deposition"; When the residence time is larger than the chemical reaction time, as-synthesized particles deposit on the plate and form the dense granular film which correspond to "aerosol deposition"; When the residence time is smaller or comparative to the chemical reaction time, mixture of vapor and particles deposits on the plate and forms the columnar film which corrpond to the mix deposition regime.…”

“…Schematic of particle formation processes during vapor-fed or liquid-fed flame synthesis through mechanisms of gas-to-particle conversion, intra-particle reaction, etc. with its location in a cylindrical reactor chamber [329]; (B) Large-scale novel atomization combining a pressure swirl nozzle (liquid hollow cone nozzle) and a dispersion gas nozzle, where α is the gas inclination angle, β is the gas swirl angle and γ is the for liquid hollow cone angle [331]; (C) Lab-scale electrospray atomizer [195]. (Reprinted with permission from literature [195][329] [331]).…”