Deposition of ballas diamond and nano-crystalline diamond

Nano-crystalline materials are of high interest, because mechanical and physical properties of such materials are different from coarse grained types. In case of diamond the CVD ballas type is a nano-crystalline material. Other names for ballas are also common; e.g. ball-shaped diamond, cauliflower like. nano-crystalline diamond. Ballas is a non-faceted. polycrystalline spherically grown diamond having a radial structure. Several morphological ballas structures have been observed by varying the deposition conditions, i.e. ballas having faceted areas, flat ballas, ballas with graphitic inclusions, etc. The nano-crystalline diamond coatings were reported during the last years and grown by adding fullerens to the deposition gas or using Ar/CH(4) mixtures with less H(2) additions. From the present point of view the ballas morphologies can be described by various microstructures. The nano-crystalline diamond is one of these microstructures. (C) 2002 Elsevier Science Ltd. All rights reserved.