Sapphire Fiber Developmental Program for High Temperature Composites

Recent developments in composites based on aluminides of titanium and nickel have shown the need for novel methods of production of cost effective methods of manufacture of continuous and discontinuous reinforcement materials. Currently, such materials as SiC provide a source of matrix fiber. In projected applications for alumides, desirable characteristics of reinforcing fibers are compatible coefficient of expansion (CTE) with the matrix, good oxidation resistance, high tensile strength at elevated temperatures and mass production feasibility, while remaining cost effective. Much work has been dedicated to development of discontinous short whisker and continuous fibers of alumina and sapphire. The CTE of alumides is more than twice that of SiC, while Aluminum Oxide more closely approaches that of potential matrix materials. What we propose is the development of a complete process in growing long whiskers of sufficient lengths to spin into multistrand thread. Further, to treat the thread via a newly developed process to further strengthen the physical characteristics such as hardness, tensile, and compressive strength. Such a process to change the wetting characteristics of the thread making it more compatible with metalization, bonding to plastics and other ceramics. The completed thread may be woven into mat as matrix reinforcement.