Abstract: The nanosized diamond powder, synthesized by explosive detonation was used as the coating material on substrates for the purpose of promoting the nucleation
and growth of CVD diamond films. Experiments show that in comparison with the scratching pretreatment with ～μm diamond particles, the nanosized diamond
coating pretreatment not only can make nucleation density higher and more homogeneous, but shorten the growth time for the formation of a continuous film. The growth process
of the films is composed of sequential two stages. The first is the growth and association of sphere shaped particles before the appearance of any facet, the second is the gradual emergence
of facets and the growth of the crystalline grain with certain facets. The films made by this pretreatment possess the following outstanding properties, such as
compact structure, low surface roughness, fine facets and high crystalline quality. In contrast, once the films deposited on the scratched substrate are nucleated,
the certain facets emerge without the former stage mentioned above, but there exist significant second nucleation on them.

Key words: nanosized diamond powder, CVD diamond thin films, growth behavior