PREPARATION OF REFRACTORY CARBIDE FIBERS BY THERMAL-DECOMPOSITION OF TRANSITION-METAL (TI, ZR, HF, NB, TA) ALKOXIDE-CELLULOSE PRECURSOR GELFIBERS

Gel fibers have been prepared by extruding cellulose acetate spinning solution into transition metal (Ti,Zr,Hf,Nb,Ta) acetone solution as a coagulation bath. Gel formation must be due to the coordination of met al to OH and CO groups on the pyranose ring. The resultant gel fibers have been converted into carbide fibers by pyrolyzing them in Ar and N -2 atmospheres at temperatures lower than for powder processing. This precursor gel can give a molecular scale mixture of metal and carbon s ources.