Avco Corporation

Thomas W Henze

Raymond J Suplinskas

Harold E Debolt

James A Cornie

Albert W Hauze

Harold E DeBolt

James V Marzik

This invention is directed to a surface treatment for SiC monofilament developed for the purpose of increasing the transverse strain-to-failure of composites, particularly aluminum composites. The surface treatment includes a fine grain SiC region adjacent to the bulk or stoichiometric SiC region and a transition region which interacts with the matrix material.

Silicon carbide monofilament for transverse composite properties

The invention relates to a surface treatment for stoichiometric silicon carbide. A carbon-rich silicon carbide layer is applied over the silicon carbide. In the case of the silicon carbide surface, the ratio of silicon to carbon in the carbon-rich layer varies from one at the silicon carbide interface to near zero in the interior of the carbon-rich layer to greater than zero and preferably 0.3 to 0.5 on the surface of the carbon-rich layer remote from the interface. A preferred method of making the silicon carbide layer is also presented.

Method of applying a carbon-rich surface layer to a silicon carbide

Coated stoichiometric silicon carbide

Silicon carbide filament is produced by overcoating a carbon monofilament core using continuous process vapor deposition. The deposition takes place by passing the carbon monofilament through a reactor into which gaseous sources of silicon and carbon are injected. At a deposition temperature of about 1300 C., a deposit of fine grained beta crystals of silicon carbide are formed. Application of a thin coating of silicon-rich silicon carbide on the surface of the filament both adds strength and provides a surface which is readily bonded to metals, glass and resin matrix materials during the forming of composite structures.

Silicon coated silicon carbide filaments and method

A refractory substrate, which generally is graphite or carbon is overcoated with silicon carbide by chemical vapor deposition from gaseous sources of silicon and carbon. The deposition generally takes place in combination with hydrogen and the coating on the substrate generally has a thickness at least equal to the diameter of the substrate itself. A silicon carbide filament containing an inner and outer surface layer of carbon rich silicon carbide, together with a method of making the same, is described.

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Lawrence, MA, United States of America

Thomas W Henze