Abstract: 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 The filament (16) is then withdrawn such that refractory material is continuously built up on its end from the chemical vapors in the enclosure to form a coreless retractory fiber.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.

Abstract: Apparatus for producing refractory material filaments comprises an enclosure (11), means for heating the constituents of the refractory material, non-contacting means to support a drop (17) of molten material such as silicon, being one of the constituents of the refractory material within the enclosure and means to transport a filament (10) such as carbon, being a second constituent of the refractory material, through the drop of molten material in use. A levitation coil and/or an inert gas jet is used to support the drop of molten material and a silica glass or other refractory tube (13) is used to direct the gas jet. The enclosure has opposed side arms (15, 16) respectively for entry and exit of the filament (10) or the filament may be passed vertically through the molten silicon drop. An inclined side tube may be provided through which grains of silicon may be introduced into the enclosure for addition to the molten drop.

Abstract: A contactless heating apparatus for thin filaments comprises means to linearly support a length of filament (10), an induction coil (11) provided adjacent to the filament with its axis substantially parallel to the length of filament, a source (15) of alternating current in the frequency range from HF to UHF connected to the coil, and a conducting rod (16) connected to one of the end turns of the indication coil (11) and disposed substantially parallel to the length of filament (20); the arrangement being such that heating of the filament occurs adjacent to the conducting rod. The filament (20) is run through a vertical cylindrical chamber (21) in which a reducing atmosphere is maintained. The coil (11) is non-uniform in diameter, the diameter being larger at the end (14) to which the rod (16) is attached and the end (12) of the coil opposite to that to which the rod is attached is earthed (13).