CORELESS REFRACTORY FIBRES

摘要

PCT No. PCT/GB91/01201 Sec. 371 Date May 19, 1993 Sec. 102(e) Date May 19, 1993 PCT Filed Jul. 18, 1991 PCT Pub. No. WO92/02109 PCT Pub. Date Feb. 6, 1992.A coreless refractory fiber is made by introducing a filament (16) of a starting material into a chemical vapor deposition (CVD) enclosure (10) and then heating the end (21) of the filament by means of a contactless heating source. The source comprises a conducting coil connected to an AC source in the frequency range HF to UHF and with a linear or strip conducting element (110) connected to it such that the ends of the element is adjacent to the end (21) of the filament. The filament (16) is then withdrawn such that refractory material is continuously built up on its end from the chemical vapors in the enclosure to form a coreless retractory fiber. Whiskers of a coreless refractory material may be made by introducing fine particles of a catalyst material to form droplets and then feeding CVD gases to the droplets (30) to thereby promote crystal growth by precipitation from the supersaturated liquid. The end of the precipitated material within the enclosure is heated by means of a linear conducting element vertically mounted and provide at its free end with a perpendicular conducting disc (111) adjacent and parallel to the platform (22). The platform is then moved vertically from the heat source such that the separation of the droplets (30) from the heating source (111) is maintained constant as chemical vapor is continuously deposited under the droplets (30) from the chemical vapors in the enclosure to form whiskers.