| One of the most promising nano-materials is nanofibrous alumina (Al 2O3) but current production methods are too slow and too inconsistent for applications outside of laboratory proof of concepts. Alumina structures were fabricated from aluminum nitrate/polyvinylpyrrolidone precursor nanofibers prepared using a novel free-surface alternating current (AC) electrospinning method. Precursor fibers were generated at the rates up to 6.4 g/h and collected as 100--300 mum thick sheets suitable for direct conversion into the nanofibrous alumina structures. A computational model of the surrounding electric field was constructed to compare to experimental observations. The effects of process conditions and annealing temperature on the nanofiber diameter, morphology, shrinking behavior and crystalline phase formation were investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). Textural properties of Al2O3 fibrous sheets composed of micro-/meso-porous nanocrystalline gamma-alumina nanofibers with 260+/-90 nm diameters after the calcination at temperatures in the range from 700 °C to 1000 °C were determined from N2 adsorption/desorption isotherms. Preliminary air permeability and apparent air flow resistance studies of single sheet and multilayer nanofibrous alumina membranes were performed and compared with other porous alumina membrane structures for possible usage in gas filtration, separation, and other applications. |
