Lx. Liu et al., A DIRECT-CURRENT, PLASMA FLUIDIZED-BED REACTOR - ITS CHARACTERISTICS AND APPLICATION IN DIAMOND SYNTHESIS, Powder technology, 88(1), 1996, pp. 65-70
In this study, the bed temperature profile of a conical/plasma fluidiz
ed bed without a distributor was studied. The same reactor was also us
ed for growing diamond by chemical vapour deposition. It was found tha
t the fluidized bed quenches the plasma gas quite significantly. The b
ed temperature increases with both the plasma gas flow rate and the pl
asma input power. A lateral temperature difference from the centre of
the bed to the wall exists due to heat loss through the wall. The temp
erature profiles obtained are suitable for controlling of bed quenchin
g conditions in particle processing and synthesis. The conical/plasma
fluidized bed with a distributor on top of the plasma was then applied
to diamond synthesis from a gas phase using a distributor between the
bed and the plasma. The deposition mainly occurred in the plasma tail
flame. Both the scanning electron micrographs and Raman spectra show
the existence of diamond on seed particle surfaces, but with a rather
low nucleation density. The limitations of the d.c. plasma fluidized b
ed system are discussed and modifications to the reactor are recommend
ed.