https://doi.org/10.1051/epjap:1998246
Diagnostic and modeling of N2-H2 discharges for iron nitriding*
1
CPAT, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
2
Centro de Fisica de Plasmas, Instituto Superior Tecnico, 1096 Lisboa, Portugal
3
LPGP-Université Paris-Sud, 91405 Orsay, France
4
Departamento de Fisica, Instituto Tecnologico de Aeronautica,
Centro Tecnico Aeroespacial, 12228-900 - Sao Jose de Campos, Brazil
5
LSGS, École des Mines, Parc de Saurupt, 54042 Nancy, France
Corresponding author: ricard.a@cpa22.ups-tlse.fr
Received:
26
December
1997
Revised:
25
May
1998
Accepted:
26
June
1998
Published online: 15 October 1998
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.
PACS: 52.20.-j – Elementary processes in plasma / 52.40.Hf – Plasma wall interactions; boundary layer effects; plasma sheaths / 52.75.Rx – Plasma applications in manufacturing and materials processing (etching, surface cleaning, spraying, arc welding, ion implantation, film deposition, etc.)
© EDP Sciences, 1998