Jj. Schermer et al., THE INFLUENCE OF DIFFERENCES IN GAS-PHASE BETWEEN TURBULENT AND LAMINAR ACETYLENE-OXYGEN COMBUSTION FLAMES ON DIAMOND GROWTH, DIAMOND AND RELATED MATERIALS, 4(9), 1995, pp. 1113-1125
This study describes the deposition of polycrystalline diamond layers
on molybdenum substrates, using both laminar and turbulent acetylene-o
xygen flames. The use of accurate temperature and flow control systems
allowed for a good comparison between diamond layers obtained by a sp
ecially designed turbulent burner and a commercially available laminar
burner. With constant oxygen flows and temperatures, the deposits obt
ained with both types of flame in general behave similarly as a functi
on of the applied supersaturation and the position of the substrate in
the acetylene feather. Usually continuous diamond layers formed by we
ll-faceted connected crystallites were obtained in the central area of
the deposits. These parts of the diamond layers are of good quality,
as judged from Raman spectroscopy and their blue band A cathodolumines
cence emission. Surprisingly the central area, as obtained by the turb
ulent flame, is somewhat smaller than from the laminar flame. This, as
well as other local differences in growth rate, morphology and impuri
ty incorporation of the deposits, is explained by a model involving th
e increased mixing rates in the turbulent flame compared with the lami
nar gas phase.