SOL GEL-BASED PRECURSORS FOR MANUFACTURING REFRACTORY OXIDE FIBERS

Several kinds of mixed refractory oxide fibres containing the oxides of Zr, Ti, Al, Cr and Ce were produced from sol/gel precursors via a melt spinning process from 50 to 110-degrees-C. For the synthesis of precursor sols the n-propoxides of Zr and Ti were reacted with chelating agents acetylacetone, ethyleneglycole, acetic acid and hydrolysis water. The surplus of solvents was distilled off, to adjust the viscosity. The viscosity and spinnability were improved by the use of N,N-dimethylformamide (DMF) as drying control chemical additive (DCCA) and different organic polymers as plastifiers. The elements Al, Cr and Ce were added to the precursor sols as chlorides, basic chlorides or basic acetates. The precursors were spun into bundles of thin gel-fibres with minimum diameters of ca. 45 mum by extrusion though multifilament spinnerets. The gel fibres were cured in air at 105-degrees-C and converted into fine grained ceramic fibres by pyrolysis at 1450-degrees-C. The decomposition process was investigated by thermogravimetric measurements (TG/DTA) and thermomechanical analysis (TMA).