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.