Nucleation enhancement of diamond by electric arcing

Enhancement of diamond nucleation by arcing on pre-existing diamond particles has been studied in the hot-filament CVD process. A positive bias of 400 volt was applied on a wire hanging over a grounded substrate. Electric arcing between the wire and the substrate occurred during heating the filament in the temperature range 900-2000 degrees C, and resulted in an enhancement of nucleation around the pre-existing diamonds. The nucleation behavior was different from that of the conventional bias-enhanced nucleation, but the maximum nucleation density was almost the same. Based on the observed microstructural features, the enhanced nucleation mechanism was proposed to be the fragmentation of diamond particles during arcing. (C) 1998 Published by Elsevier Science S.A. All rights reserved.