PREPARATION OF MICRO-COILED TIC FIBERS BY METAL IMPURITY-ACTIVATED CHEMICAL-VAPOR-DEPOSITION

Micro-coiled TiC fibers have been directly prepared on a graphite substrate from TiCl4 + H-2 + PCl3 gas mixtures at 1050 degrees C by the Si + Pd mixed impurity-activated CVD process. It was found that the presence of small amounts of PCl3 in the source gas as well as Si + Pd mixed impurities were indispensable for the deposition of the micro-coiled TiC fibers. The obtained coiled TiC fibers were in a polycrystalline state with a 1-5 mu m coil diameter and 20-150 mu m coil length. The TiC coils were generally double coils similar to DNA.