Coreless refractory fibers

Details Coreless refractory fibers Coreless refractory fibers

1993-08-19

1995-07-11

Padgett, Marianne

Coating processes

Direct application of electrical, magnetic, wave, or...

Pretreatment of substrate or post-treatment of coated substrate

427585, 427587, 427557, 427546, 427251, 117 87, 117 93, 117 98, B05D 306, C23C 1600

Patent

active

054319650

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to the manufacture of refractory fibers and in particular to coreless fibers.
2. Discussion of Prior Art
GB Patent Application No 8811893 describes a method of radio frequency heating which allows lengths of fine wires to be heated uniformly or with a desired temperature gradient without physical contact with the wire. GB Patent Application No 9005172 further discloses that uniformity of the heating of the wire can be improved by modulating the radio frequency source. These methods allow convenient manufacture of refractory fibers or filaments by chemical vapor deposition (CVD) on a core wire, typically tungsten. Such fibers do not have optimum properties, however, because several well known deleterious core effects impair the properties of the refractory material deposited on the core.


SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for making coreless refractory fibers, filaments or whiskers.
The invention provides, in one form, a method for making a coreless refractory fibers comprising the steps of: material into a chemical vapor deposition (CVD) enclosure; contactless heating source, the source comprising a conducting coil connected to an AC source in the radio frequency range HF to UHF and with a linear or strip conducting element connected thereto such that the end thereof remote from the coil is adjacent to the end of the filament; and built up on the end of the filament from the chemical vapor in the enclosure to form a coreless refractory fiber.
Advantageously the fiber is made of tungsten or carbon or a multiple of strands of such materials. In an advantageous arrangement the starting filament is selected to be tungsten and is supported vertically in the CVD enclosure and the linear conducting element of the heating source is arranged to be parallel or perpendicular to the filament. Alternatively the conducting element may be a conducting cylinder, advantageously with an axial slit for viewing, coaxially surrounding the end of the starting filament.
Preferably the CVD enclosure is selected to be cylindrical and provided at the upper end thereof with a gas seal for entry of the filament into the enclosure. Advantageously the gas seal may be formed with a guard enclosure through Which an inert gas is circulated and provided with opposed capillary inlet, open to the atmosphere, and outlet, connected to the CVD enclosure, through which the filament passes. Advantageously a plurality of filaments may be introduced into the CVD enclosure by arranging that the guard enclosure has more than one pair of inlet and outlet through which respective filaments can be passed. In this arrangement the heating source may be arranged such that there is provided a plane conducting strip conducting element and formed such that the plane thereof is parallel to a plane through the ends of the filaments. The quality of the coreless fiber may be enhanced by conducting the deposition of the refractory material (e.g. Si C) under reduced pressure.
In another form the invention provides a method for making whiskers of a coreless refractory material comprising the steps of: inside a chemical vapor deposition (CVD) enclosure; thereby promote crystal growth by precipitation from the supersaturated liquid; contactless heating source comprising a conducting coil connected to an AC source operating in the frequency range HF to UHF and a linear or strip conducting element connected to the coil and aligned adjacent and parallel to the platform; and vertically so as to maintain constant the distance between the liquid droplets and the conducting element such that chemical vapor is continuously deposited under each liquid drop from the chemical vapor in the enclosure to form whiskers. In one form the conducting element may be mounted vertically and provided at its free end with a perpendicular conducting disc arranged such that the disc is adjacent and parallel to the platform.


BRIEF DESCRIPTION OF THE DRAWINGS

The in

REFERENCES:
patent: 2877138 (1959-03-01), Vodonik
patent: 3622369 (1971-11-01), Basche et al.
patent: 3887722 (1975-06-01), Douglas et al.
patent: 4107352 (1978-08-01), Hakim
patent: 4142008 (1979-02-01), DeBolt
patent: 4221825 (1980-09-01), Guerder et al.
patent: 4224046 (1980-09-01), Izawa et al.
patent: 4259101 (1981-03-01), Tsukuda et al.
patent: 4345930 (1982-08-01), Basola et al.
patent: 4357365 (1982-11-01), McCarty
patent: 4676814 (1987-06-01), Ross et al.
patent: 4756791 (1988-07-01), D'Angelo et al.
patent: 5094711 (1992-03-01), Narasimhan et al.
patent: 5160574 (1992-11-01), Pearson et al.
patent: 5294465 (1994-03-01), Gallagher
patent: 5304461 (1994-04-01), Inoue et al.
Webster's 9th New Collegiate Dictionary, 1990 (no month), Merriam-Webster Inc. Pub., Springfield, Mass. USA. p. 971.

Affiliated with

Also associated with

Rating

Coreless refractory fibers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Coreless refractory fibers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coreless refractory fibers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-502086