Flame Structure and Diamond Growth Mechanism of Acetylene Torch

Abstract

To understand the diamond growth mechanism in C 2 H 2 /O 2 flame, we carried out gas analyses for various mixture ratios ( R =C 2 H 2 /O 2 ) with laser-induced fluorescence and mass spectrometric techniques. These measurements show that CO and H 2 are the dominant gases in the feather, and that C 2 H 2 and C -containing radicals ( e.g. , C 2 H, CR, Cn, n =1-3) are minor species. Their concentrations are found to be consistent with the equilibrium values estimated by the adiabatic calculation. The feather is formed by the inter-diffusion and reactions between these C -radicals and O -radicals ( e.g. , O and OH), which are produced in the intermediate zone by the oxidation with O 2 supplied through the secondary flame. It is also found that R -dependences of the diamond growth rate is in good agreement with those of CH and C 2 concentrations in the feather.