The production of N and H atoms has been studied in DC
and HF N2-H2 flowing discharges and post-discharges
in connection with nitriding of iron substrates. Experimentally, the N and
H atoms have been detected by emission
spectroscopy and Laser Induced Fluorescence (LIF).
A strong increase of the Mayn gas atom density (N or
H) was found when a small amount of a second gas
(H2 or N2) was added. This increase in N
or H atom densities is interpreted by a model describing the
kinetics in the reactive gas volume and on the surface of the reactor walls
(pyrex tube). In particular, it is shown that the destruction probabilities of
N and H atoms on the tube wall are reduced by a factor
of about 2 as a few % of H2 or N2 is introduced
into N2 or H2. Correlations are established
between the density of N and H atoms and the thickness
and quality of iron nitride layers growing on iron substrates located within a reactor
and placed in the post-discharge of a N2−H2 HF flowing discharge.
Under the conditions of maximum N and H atom density,
thick ϵ−Fe2N1−x layers without iron oxide superficial sublayer
have been found on the iron surface.