Extrusion of polycrystalline ceramic fibers

摘要

Submicron powders of several technically interesting advanced ceramics have been conventionally extruded as fibers and hollow fibers. Alumina, partially stabilized zirconia, silicon nitride, silicon carbide, lanthanum strontium manganate, leadzirconate titanate and a silicon carbide/zirconium diboride particulate composite have each been blended with thermoplastic or aqueous binders and extruded. The green extrudates have diameters ranging between 50 and 150μm, and polyethylene-based 150μmfibers can be drawn down at elevated temperature to approximately 40 μm diameter. Hollow fibers with 150μm outer and 90μm inner diameter can also be fabricated.Green fibers were processed into chopped fiber felts for use as gas distributors/current collectors in an experimental SOFC, and the first attempts at producing simple textile structu res were successful.The fibers, tubes, and felts were successfully debound and sintered, and characterization of the sintered PSZ fibers, for example, has revealed a density in excess of 99 % and tensile failure stresses up to 1,0 GPa for 78μm diameter fibers.