Composite 4YSZ-Al2O3 Nanofibers Prepared by Electrospinning and Thermal Processing

Abstract

The relationship between solution properties and processing parameters for novel yttria-alumina-zirconia nanofibers electrospun in a constant electric field is explored through systematic variation of precursor content and aging of the polymer gel. The upper solution viscosity and conductivity limit for electrospinning with an electric field strength of 0.84 kV/cm were ~1000 cP and ~5 mS/cm, respectively. There is a predictive relationship between volumetric flow rate and solution viscosity, conductivity, and surface tension; however, there is not a strong relationship between as-spun fiber diameters, ranging between 100 and 300 nm, and any solution property. The gelation mechanism by which aqueous polyvinylpyrollidone (PVP), zirconium acetate, and aluminum/yttrium nitrate solutions age is speculated to arise from zirconium acetate hydrolysis and polymerization, facilitating intermolecular hydrogen bonding between zirconium acetate complexes, PVP functional groups, and disassociated ionic species. The 4YSZ-Al 2 O 3 ceramic nanofiber diameters ranged between 50 and 100 nm depending on the volume percent of the ceramic phases. The annealed fibers appear amorphous and without excessive grain coarsening, indicating that a heat treatment of 1000°C for 2 hours is sufficient to produce tough, refractory nanofibrous membranes relevant for high-temperature filtration applications.