Abstract
In this study, the use of thin Si interlayers (35-150 nm) for promoting
diamond deposition onto steel is investigated. The diamond films are deposited
by hot filament CVD onto AISI type 316 stainless and high-speed steels.
Single stage deposition at substrate temperatures ranging from as low as
475 to 750 °C is found to result only in non-continuous films with
low number densities of diamond crystallites. A composite film of diamond
and carbides is formed at intermediate temperatures of about 650 °C.
It is believed that the formation of iron silicide phases at the exposed
steel substrate surfaces leads to diffusion barriers for free iron from
the steel matrix, so that graphitic soot formation is significantly avoided.Utilizing
a two-stage deposition process, the density and uniformity of the deposited
diamond films areincreased and a nearly continuous cauliflower shaped diamond
film is obtained. Micro-Raman spectros-copy, scanning electron microscopy
and X-ray diffraction techniques are employed to study the phases, morphology,
composition, quality and residual stresses of the grown diamond layers.