Patent ID: 6410087
Filing Date: 2002-06-25
Classification: C23C

Abstract:
In a process for depositing pyrolytic carbon from a gaseous atmosphere in a defined region having a bottom surface and a generally vertical lateral boundary, which process includes the steps of injecting a gaseous atmosphere into a lower portion of said defined region so as to levitate small substrates present when said region, said atmosphere including an inert carrier gas and a carbonaceous substance, and heating said defined region and said levitated substrates to a temperature such that said carbonaceous substance pyrolytically decomposes to deposit pyrolytic carbon upon the surfaces of said substrates, the improvement which comprisesinjecting said gaseous atmosphere into said defined region as a plurality of individual streams so as to create an asymmetric ascending and descending fluidized bed in opposite halves of said defined region with a first one of said individual streams including said carbonaceous substance and a second one of said streams consisting essentially of inert carrier gas, and with said second stream being injected in a location so as to initially flow in a region between said first stream and the boundary surface along which it upwardly flows, whereby uniform pyrolytic carbon coatings are deposited upon said substrates.