Abstract
In this report, we present a study of diamond deposition on pure and
nitrided chromium substrates using the hot filament-assisted chemical vapour
deposition technique. Deposition was performed at substrate temperatures
varying from 475 to 750 °C for different exposure times. Scanning electron
microscopy (SEM), micro-Raman spectroscopy and X-ray diffraction (XRD)
techniques were employed to study the modified interlayers and diamond
films. The high solubility and diffusivity of carbon in pure chromium result
in an increased incubation time for diamond nucleation. However, even a
4–5-m-thick nitrided layer is efficient as a diamond-nucleating surface,
with a reduced incubation time as compared to pure chromium. Fully covering
and adhering diamond films were obtained on the nitrided Cr specimens at
temperatures between 550 and 750 °C. As a result of the nitriding process,
the nitride diffusion layer reduces the carbon solubility at the substrate
surface, thereby reducing the incubation time for diamond nucleation. Due
to the strong chemical and mechanical bonding of the diamond films to the
nitrided Cr substrates, the residual compressive stresses are accommodated,
leading to adherent, continuous diamond films. The present study, however,
also indicates an optimal low-temperature deposition condition to obtain
a continuous diamond film directly on pure Cr.