MATRIX ALLOY DEVELOPMENT FOR GRAPHITE/METAL MATRIX COMPOSITES

THE USE OF GRAPHITE/METAL COMPOSITES FOR SPACE STRUCTURE APPLICATIONS REQUIRING ZERO THERMAL EXPANSION CHARACTERISTICS HAS BEEN HAMPERED BY THE PROBLEM OF HYSTERESIS CAUSED BY MATRIX YIELDING. THIS HYSTERESIS HAS BEEN ELIMINATED IN LABORATORY SAMPLES BY HEAT TREATING THE COMPOSITE TO OBTAIN A MATRIX YIELD STRENGTH IN EXCESS OF 40 KSI OR THROUGH THE USE OF THERMAL CYCLING OF THE COMPOSITE MATERIAL. THESE THERMAL TREATMENTS, ALTHOUGH PRACTICAL FOR LABORATORY SAMPLES, BECOME IMPRACTICAL WHEN LARGE (15 METER LONG TUBES) STRUCTURES ARE MANUFACTURED. THE OBJECTIVE OF THIS PHASE I PROGRAM IS TO DEMONSTRATE THE FEASIBILITY OF PRODUCING A HYBRID GRAPHITE/METAL COMPOSITE MATERIAL WHICH, WITHOUT THE NEED FOR THERMAL TREATMENTS, WOULD EXHIBIT LITTLE OR NO THERMAL HYSTERESIS.