Continuous silicon nitride fibers produced by reductive nitridation of silica-phenolic resin hybrid fibers

Continuous silicon nitride fibers have been synthesized from silica-phenoli c resin hybrid fibers, produced by sot-gel processing from tetraethoxysilan e and novolac-type phenolic resins, by heat treatment over 1500 degreesC un der N-2 atmosphere. The flowing rate of N-2 gas, carbon-to-silicon atomic r atio of the hybrid fibers, heating temperature, and holding time have been determined so that pure silicon nitride fibers are formed. The nitride fibe rs with a N content of 36.32 wt % could be produced upon heating the hybrid fibers with a carbon-to-silicon atomic ratio of 2.6 at 1530 degreesC for 3 h in N-2 at a flowing rate of 500 cm(3) min(-1).