A SURFACE AND A GAS-PHASE MECHANISM FOR THE DESCRIPTION OF GROWTH ON THE DIAMOND(100) SURFACE IN AN OXY-ACETYLENE TORCH REACTOR

A gas-phase and a surface mechanism were developed, suitable for multi dimensional simulations of diamond oxy-acetylene torch reactors. The g as-phase mechanism was obtained by reducing a 48 species combustion ch emistry mechanism to a 27 species mechanism with the aid of sensitivit y analysis. The surface mechanism for growth on monocrystalline (100) surfaces developed, was based on literature quantum-mechanical calcula tions by Skokov et al. It consists of 67 elementary reaction steps and 41 species, and contains CH3 and C2H2 as gas-phase growth precursors and atomic hydrogen and oxygen to etch carbon from the surface. The ga s-phase and surface chemistry models were tested in one-dimensional si mulations, yielding dependencies of the growth rate on feed compositio n and surface temperature that are in qualitative agreement with the e xperiments. A more detailed study of the surface chemistry showed that , compared to CH3, acetylene contributes very little to diamond growth . Furthermore, molecular and atomic oxygen do not affect the diamond s urface as much as atomic hydrogen because of their low concentrations. (C) 1998 American Institute of Physics. [S0021-8979(98)05423-1].