Diamond deposition on 3d transition metals and their alloys

The characteristics of formation of diamond films using hot-filament chemical vapor deposition on nickel and nickel-aluminum alloys have been investigated systematically. It has been found that the chemical nature of the substrate plays an important role in stabilization of graphite (sp2-bonded) or diamond (sp3-bonded) phase. The transition metal substrates with a partially filled 3d shell, for example nickel, tend to stabilize sp2 bonding and catalyze the formation of graphite. By alloying the substrate with aluminum, it was possible to form diamond directly on the NiAl substrates. The mechanism of formation of diamond on nickel-aluminum alloys, and the nucleation of diamond on single crystal graphite substrates are discussed. The importance of diamond coating on these technologically important structural alloys is described briefly.