Consolidation of Diamond and SiC Particulate Preforms by the Forced Flow-Thermal Gradient Diamond CVI Process

The forced flow-thermal gradient diamond CVI process was used in an attempt to densify and consolidate SiC and diamond preforms by forcing the stream of reagent gases through the preforms for infiltration of diamond coatings. Reasonable quality polycrystalline diamond was deposited on the cold surface of SiC preforms where the concentration of reagent gases was high. The growth rate of diamond on SiC preforms was increased from 0.085 to 0.5 μm/h when the deposition temperature and time were increased. Graphite fibers were deposited throughout a diamond preform using a mixture of H2 and CH4.