Patent attributes
A pressure gradient CVI/CVD process includes providing a furnace defining an outer volume. Porous structures and ring-like spacers are assembled in a stack with a ring-like spacer between each adjacent pair of porous structures. The stack of porous structures is disposed between a bottom plate and a top plate in the furnace, wherein the bottom plate, the stack of porous structures, and the ring-like spacers define an enclosed cavity. A channel provides fluid communication between the enclosed cavity and the outer volume. A gas composition is introduced into the enclosed cavity. A portion of the gas composition flows through the channel. A pressure gradient is maintained between the enclosed cavity and the outer volume. The gas composition in the outer volume is provided at a pressure of at least about 15 torr. The porous structures are densified.
