Deposition of an adherent diamond film on stainless steel using Cr/CrAlN as an interlayer

Cr/CrAlN films were chosen as an interlayer to deposit an adherent diamond film on stainless steels by using hot filament chemical vapor deposition (HFCVD). The results show that diamond film with good adhesion is successfully deposited on 3Cr13 stainless steel when the interlayer with Al content from 0 to 18 at.%, which is ascribed to high chemical adhesion by a certain amount of chromium carbide. When Al content in the interlayer further increases, an excessive Al2O3 is formed on the surface of the interlayer, carbon supersaturation is easily arrived, so that the amount of the carbide at the diamond/interlayer interface decreases evidently. This decreases the strength of the covalent bonding from the carbide, producing poor adhesion. Moreover, with the raise of Al content in the interlayer, the hardness of the multilayer coated stainless steel increases due to the increase of the interlayer's hardness and the slight increase of the diamond content in the film.