DIAMOND FIBERS FOR THERMAL-ENERGY MANAGEMENT

Properties of paramount importance in thermal management are thermal c onductivity and the coefficient of thermal expansion (CTE). The use of carbon fibers has led to significant improvements in the properties o f composites of various polymeric, metal and ceramic matrices, but ani sotropy of the thermal conductivity and CTE in high thermal conductivi ty graphitic fibers is a limiting factor. In order to tailor the therm ophysical properties of composites, new fibers with isotropic thermoph ysical properties are required. This research addresses the developmen t of diamond fibers, which have the highest thermal conductivity of an y material found in nature, a near-isotropic thermal conductivity and a CTE nearly matching that of semiconductor materials. Both single-cry stal and polycrystalline diamond fibers were attempted. For the polycr ystalline diamond fibers, Raman and scanning electron microscopy analy ses show that diamond coatings were successfully applied to a graphiti c fiber substrate. Also, some evidence supports the feasibility of sin gle-crystal diamond fiber formation.