A modified strip furnace was used to heat diamond crystals of various
sizes (1-10 mu m) to 2200 degrees C in a hydrogen atmospheres (1 aim t
otal pressure), and their thermal stability and growth were investigat
ed. Graphite fibers coated with 1, 5 and 10 mu m diamond seeds were us
ed as the resistive element in the modified strip furnace and heated i
n the hydrogen atmosphere. It was found that diamond seeds of these si
zes survive in a hydrogen atmosphere ar temperatures as high as 2200 d
egrees C. Considerably smaller crystals (compared with the original di
amond seeds) are also observed on the surface of the graphite fibers,
suggesting new diamond growth under these conditions.