Direct
deposition of diamond films on steel using a three-step process
M. Gowri, H. Li, J.J. Schermer, W.J.P. van Enckevort and J.J. ter
Meulen
Abstract
Diamond coatings were successfully deposited on tool steel substrates
without using any external diffusion barrier layers. The diamond film
deposition was performed in a hot filament chemical vapour deposition
(HFCVD) reactor. In the first step, a high substrate temperature and a
high methane percentage were used to achieve a faster critical carbon
concentration and hence a shorter incubation time for diamond
nucleation. Subsequently, the substrates were taken out of the reactor
and subjected to ultrasonic scratching in diamond slurry in order to
increase the diamond nucleation density. Then the final deposition was
performed in the reactor under typical diamond growth conditions. X-ray
diffraction analyses showed that Fe3C was the dominant carbide phase
formed on the steel surface after the first step. The carbides produced
in the first step act as a diffusion barrier for both iron and carbon.
Thus, they accelerate the diamond nucleation and help further diamond
growth. Scotch tape adhesion tests showed that the diamond film adheres
well to the substrate.