Ceramic fibers from sol-gel precursors

Powderless methods for the preparation of continuously spinnable alumina, mullite, spinel, yttrium allumina garnet (YAG) and lead zirconium titanate (PZT) precursors are presented. The Al containing solutions are based on alcoholysis, carboxylation and hydrolysis reactions, which are described in detail. In addition, a synthesis route for the preparation of piezoelectric PZT long fibers has also been developed. This novel PZT precursor contain lead subcarboxylate and zirconium titanium oxohydroxocarboxylate. In all cases, continuously spinnable precursors, which have been extruded with velocities up to 200m/min, have been obtained. Gel fibers of several kilometer length could be drawn directly from sols. After drying, pyrolysis and sintering, each of the alpha-Al2O3, mullite, spinel, YAG and PZT fibers have been obtained.