SOL-GEL PROCESS FOR SPINNING OF CONTINUOUS (ZR, CE)O-2 FIBERS

A sol-gel precursor for the production of continuous fully stabilized Ce-17mol.%ZrO2 or Mg-17mol.%ZrO2 ceramic fibers was developed using zirconium n-propoxide, cerium(III) chloride or magnesium acetate. The organic additive acetylacetone was used to control the hydrolysis rate, dimethylformamide as a drying control chemical additive and polyethyleneglycol or polyvinylpyrrolidone as a plasticizer. The precursors with acetylacetone-to-Zr molar ratios from 0.3 to 0.75, H2O-to-Zr molar ratios from 1.2 to 1.8 and dimethylformamide-to-Zr molar ratios of 2 showed excellent spinnability. Gel fibers were produced in the temperature range from 50 to 100 degrees C using a piston-driven melt-spinning machine with multifilament spinnerets (10-100 holes) in combination with a winding machine. After heat treatment up to 1450 degrees C the ceramic fibers had diameters of about 40 mu m and consisted of a mixture of tetragonal and cubic (Zr0.83Ce0.17)O-2 having a density of 98% of the theoretical density.