An improved procedure for fabricating SiO 2-TiO 2-phenolic resin hybrid fibers as precursors for long Si-Ti-C fibers by sol-gel processing

Abstract

Synthesis conditions for producing SiO 2-TiO 2-phenolic resin hybrid fibers with a wide range of Si-to-Ti atomic ratios from tetraethoxysilane, titanium tetrakis(2,4-pentanedionate) and novolak-type phenolic resins by sol-gel processing have been investigated. It was found that 2,4-pentanedione was an effective solvent for the sol-gel reaction in order to produce the hybrid fibers. For favorable spinn-ability of the hybrid fibers from the solutions it was necessary to adjust critically the amounts of H 2O and of acid, which were added to promote hydrolysis and polycondensation of the Si and Ti compounds in the solutions, according to their Si-to-Ti ratios. The amounts found to be optimal for spinning the hybrid fibers were in proportion to the Si-to-Ti ratio of the solutions. Using these combinations, SiO 2-TiO 2-phenolic resin hybrid fibers with various Si-to-Ti ratios could then be produced, which could then be converted into Si-Ti-C fibers by carbothermal reduction at 1500 °C in Ar.