A SAXS STUDY OF THE CERAMIZATION PROCESS OF SI-C ORGANIC PRECURSOR

Amorphous Si-Ti-O-C ceramic fibers are prepared from organic precursor fibers by heat treatment above 10000 degrees C. Small-angle X-ray sca ttering (SAXS) measurements have detected a structural change accompan ying an increase in mechanical strength of the fibers arising from an increase in heal-treatment temperature. The scattering profiles of Si- TiO-C fibers heal treated at temperatures below 800 degrees C differ f rom those heat-treated at higher temperatures above 1000 degrees C. Th e former profiles are fit by Gaussian functions, while the latter prof iles can be fitted using the Percus-Yevick model of particle scatterin g including the concept of a depleted zone. The SAXS measurements show ed that structural changes occur over a length scale greater than 1.5 nm for fibers heat-treated at temperatures between 500 degrees C and 1 000 degrees C, (C) 1998 Published by Elsevier Science B.V, All rights reserved.