Effect of the chemical nature of transition-metal substrates on chemical-vapor deposition of diamond

Abstract

Chemical-vapor deposition of diamond on transition-metal substrates of Cu, Ni, Fe, and their alloys NiAl, Ni3Al, FeSi2, and FeSi has been investigated. It is shown that diamond grows easily on Cu with a very small amount of graphite, while on Ni and Fe there is rapid growth of the graphite layer before diamond deposition. The formation of graphite is attributed to the decomposition of carbon-containing precursors due to the strong catalytic reactivity of Ni and Fe substrates with carbon. The deactivation of these substrates by forming NiAl and FeSi2 results in the suppression of graphite and formation of high-quality diamond. However, for Ni3Al and FeSi substrates which are not completely deactivated, deposition of graphite still takes place. A mechanism based on the electronic structure of substrate atoms, particularly on the 3d shell structure of Cu, Ni, and Fe is proposed to understand the above behavior. Requirements for the stabilization of sp3 bonding of carbon on different substrates are discussed.

Plasma boriding of a cobalt–chromium alloy as an interlayer for nanostructured diamond growth

“…The cobaltchromium-molybdenum (CoCrMo) alloy used for these implants is an ideal material in terms of stress and strain properties; however, over time repetitive motion can cause wear of the implant and release toxic calcium depleting metals [3,4]. Diamond coatings represent a potentially viable solution to reduce wear and metal diffusion, but unlike many existing diamond coating processes it is not possible to directly grow well adhered diamond onto cobalt-chromium alloys due to graphitic nucleation leading to poor diamond adhesion [5][6][7].…”

Chemically vapour deposited diamond coatings on cemented tungsten carbides: Substrate pretreatments, adhesion and cutting performance

“…During the initial stages of the CVD process, the WC-Co is exposed to a hydrocarbon radical rich atmosphere and carbon species can rapidly diffuse into the bulk of the binder phase until the carbon solubility is exceeded. Co being a transition metal with partially filled 3d shell, it acts as a catalyst for the formation of graphite [12]. Therefore, once the carbon concentration at the substrate surface is sufficiently large to promote solid carbon condensation, the preferential formation of a graphite layer is promoted by the presence of the binder.…”

Adherent diamond coatings on cemented tungsten carbide substrates with new Fe/Ni/Co binder phase

“…During the initial stages of the CVD process, the WCCo is exposed to a hydrocarbon radical-rich atmosphere and carbon species can rapidly diffuse into the bulk of the binder phase until the carbon solubility is exceeded. Cobalt, like Ni and Fe, is a transition metal with partially filled 3d shell, and it acts as a catalyst for the formation of graphite [16]. Therefore, once the carbon concentration at the substrate surface is sufficiently large for solid carbon condensation, the preferential formation of a graphite layer is promoted by the presence of the binder.…”