Exxon Research and Engineering Company

Other

The United States of America as Represented by the United States

John V Milewski

Franklin J Wright

James A Amick

Carl E Heath

Daniel Grafstein

Peter D Milewski

Described herein is a method and apparatus for continuously growing single crystal whiskers of silicon carbide, silicon nitride, boron carbide and boron nitride by the VLS process under controlled reaction conditions. A growth substrate such as a plate of solid graphite is coated with a suitable VLS catalyst and is conveyed through a tubular furnace, into which is separately introduced two feed gases. The first feed gas contains a cationic suboxide precursor such as silicon monoxide or boron monoxide. The second feed gas contains an anionic precursor compound such as methane or ammonia. The precursor compounds react upon exposure to the catalyst by the VLS process to produce crystalline whiskers. The associated apparatus includes a conveyor assembly that continuously circulates multiple substrate growth plates through the furnace and past a harvesting device which brushes the whiskers from the plates and removes them by vacuum collection. Whiskers of uniform size, shape, and purity are produced.

Method and apparatus for continuous controlled production of single

An electric light filament comprising a single crystal whisker is disclosed. In the preferred embodiment the whisker consists essentially of silicon carbide (SiC), preferably beta silicon carbide, doped with a sufficient amount of nitrogen to render the whisker sufficiently electrically conductive to be useful as a light bulb filament at household voltages. Filaments made of such materials are characterized by high strength, durability, and resilience, and have higher electrical emissivities than conventioanl tungsten filaments.

Single crystal whisker electric light filament

A method of producing articles comprising reaction-bonded silicon carbide (SiC) and graphite (and/or carbon) is given. The process converts the graphite (and/or carbon) in situ to SiC, thus providing the capability of economically obtaining articles made up wholly or partially of SiC having any size and shape in which graphite (and/or carbon) can be found or made. When the produced articles are made of an inner graphite (and/or carbon) substrate to which SiC is reaction bonded, these articles distinguish SiC-coated graphite articles found in the prior art by the feature of a strong bond having a gradual (as opposed to a sharply defined) interface which extends over a distance of mils. A method for forming SiC whisker-reinforced ceramic matrices is also given. The whisker-reinforced articles comprise SiC whiskers which substantially retain their structural integrity.

Method of producing silicon carbide articles

The present invention relates to the production of high purity solar grade silicon from common rice hulls. A unique process for material purification and reduction includes leaching the rice hulls in acid followed by treatment with high purity water, coking the acid-cleaned hulls in a non-oxidizing ambient, compensating the carbon or silica content of the coked hulls to obtain a desired carbon to silica ratio and reducing the silica to produce high purity silicon.

Method for producing solar cell-grade silicon from rice hulls

Adherent layers of glass are deposited on a preform or substrate via the controlled oxidation of a glass precursor, such as silicon monoxide, in the vapor state, thereby providing unusual shaped composite articles having a glass coating on the substrate. A preform or substrate such as carbon can subsequently be oxidized, thereby providing a glass microcapillary of exceedingly uniform dimensions.

Forming a glass on a substrate

This invention relates to an article of manufacture comprising a mixture of fiber and sphere materials in substantially optimum packing condition between said materials, each of said materials being present in selected fractional loadings in said mixture, said fibers having a definite length to diameter ratio and said spheres having a selected diameter predetermined in relation to its loading in the mixture and the ratio of its diameter to the diameter of the fibers for said given length to diameter ratio of said fibers thereby to provide an efficient packing condition in said article.

Growing community of inventors

Los Alamos, NM, United States of America

John V Milewski