SYNTHESIS OF CERAMIC FIBERS IN THE SI-O-C SYSTEM

Ceramic fibers consisted of three elements, Si, O and C, were synthesized from carbide obtained from a natural organic material; rice husk. TEM was used to analyze the synthesized fibers. One fiber synthesized in N2 consisted of a two-layered structure of laminate covering a center core fiber. Another fiber synthesized in a mixture of N2 and H-2 consisted of a three-layered structure of two laminates covering a core fiber. The fiber core was found to be crystallized and covered with an amorphous material, which contained concentrated oxygen. The core fiber did not dissolve in strong acid solutions and was very reactive with oxygen. From the results of X-ray diffraction and solubility in acid solution, it was found that the inside laminate from the surface layer to the core of the fiber formed a structure which was crystallized weakly into beta-SiC, and Si-O-C. This study clearly shows that fiber synthesized from rice husk formed a continuous structure with varying concentration of oxygen and carbon-bound silicon; that is a new material with gradient structure.