SURVIVAL OF DIAMOND AT 2200-DEGREES-C IN HYDROGEN

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.