Compatibility problems generated in graphite fiber--metal matrix composites

The matrix of graphite fiber reinforced resin composites limits their useful temperature of application to a maximum of about 300°C. Efforts have been made to increase the usable temperature of graphite fiber composites by incorporating the fibers into metal matrices. The present study describes the work in this area and covers aspects such as chemical compatibility, composite fabrication technology and mechanical properties.

The single graphite fibers coated with nickel have been shown to undergo structural recrystallization. Techniques have been developed to stop the structural recrystal1ization by coating the fibers with barrier coatings such as pyrolytic graphite.

A method of composite fabrication has been developed. Graphite-7075A1 alloy, graphite-Pb, 2 percent Sn alloy, and graphite-Zn, 2 percent Sn alloy composites have been fabricated by liquid metal infiltration of nickel-coated graphite fibers. Nickel coating acts as a coupling agent to improve the wetting of graphite fibers by molten metals or alloys. A heat-treatment method has been developed to improve the tensile strength of graphite-Al composite. Typical mechanical and physical properties of these composites are presented, and potential applications for these materials are explored.