Diamond film synthesis in low pressure premixed flames of different fuel types

Abstract

Various aspects of diamond film growth in low pressure flames are presented. Experiments are performed in a low pressure flat flame facility and diamond films are deposited on molybdenum substrates over areas of at least 2 cm 2 or 5.5 cm 2. Pure acetylene-oxygen (C 2H 2-O 2), ethylene-oxygen (C 2H 4-O 2), and methane-oxygen (CH 4-O 2) premixed flames are studied and compared for their use in depositing high quality diamond films. It is found that uniformity and quality are very sensitive to substrate temperatures T s and flame equivalence ratios φ and vary between flames of different fuel types. The growth behavior in response to changes in fuel types is interpreted in terms of burning velocities, which determines the residence times of intermediate species in the post-flame region and strongly influences the flux of reactants to the substrate surface. These results can be used to project alternative, perhaps more cost-effective flame synthesis strategies to deposit diamond coatings.