Lanxide Technology Company, LP

M Cubed Technologies, Inc.

Brian E Schultz

Michael K Aghajanian

Allyn L McCormick

Michael A Richmond

W Michael Waggoner

Techniques to bond two or more smaller bodies or subunits to produce a unitary SiC composite structure extend the capabilities of reaction-bonded silicon carbide, for example, by making possible the fabrication of complex shapes. In a first aspect of the present invention, two or more preforms are bonded together with a binder material that imparts at least strength sufficient for handling during subsequent thermal processing. In a second aspect of the present invention, instead of providing the subunits to be bonded in the form of preforms, the subunits may be dense, SiC composite bodies, e.g., RBSC bodies. In each of the above embodiments, a preferable means for bonding two or more subunits combines aspects of adhesive and mechanical locking characteristics. One way to accomplish this objective is to incorporate a mechanical locking feature to the joining means, e.g., a 'keyway' feature. The mechanical locking feature thus substitutes for, or supplements the binder qualities of the adhesive, which is especially important when the adhesive itself may be or become weak due to, for example, thermal processing.

Methods for making composite bonded structures

Often, metal matrix composites (MMC's) lack adequate machinability and possess excessive abrasiveness because hard ceramic materials, such as silicon carbide, are used as the reinforcement phase. To make a metal matrix composite body having a more machinable and less abrasive surface, an MMC comprising an aluminum nitride reinforcement is formed on the surface of the body. In one embodiment, a layer is provided to a permeable mass or preform at the surface at issue, the layer featuring at least a reduced loading of ceramic filler material, and sometimes no ceramic material at all. The reduced loading is achieved by incorporating a fugitive material into the coating layer. Molten matrix metal is caused to infiltrate the permeable mass or preform and the coating layer to produce a macrocomposite body comprising a metal matrix composite coating and substrate. The metal matrix composite coating layer is distinguishable from the metal matrix composite substrate material, both compositionally and in terms of resulting properties. Under spontaneous infiltration conditions, as defined herein, aluminum nitride forms in-situ in the infiltrated body, including the surface layer. The present coating technique, however, permits a thicker MMC surface layer to be produced than could be produced previously. The present MMC surface layer can be applied to virtually any reinforced or unreinforced aluminum or aluminum alloy body.

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Kennett's Square, PA, United States of America

Brian E Schultz