Abstract

CAMPS, E,; ESCOBAR-ALARCON, L.; CHIRINO, S.  and  MEJIA-HERNANDEZ, J. A.. Microwave ECR plasma nitriding of AISI 4140 steel. Superf. vacío [online]. 2005, vol.18, n.3, pp.33-35. ISSN 1665-3521.

A microwave electron cyclotron resonance plasma source (ECR) was employed to modify the mechanical surface characteristics of pieces of AISI 4140 steel. Experiments were carried out in a pressure range between 4 x 10-4 and 7 x 10-4 Torr, using a 60/40 hydrogen/nitrogen gas mixture and an incident microwave power of 400 W. Prior to the samples treatment the plasma was studied using a Langmuir probe to determine the electron temperature and the plasma density, the excited plasma species were determined by means of optical emission spectroscopy. All samples were treated for 50 min. in a low temperature regime (∼ 250 oC) and the surface hardness increased up to 100 % of the initial value, with a nitrogen depth penetration of about 7.5 microns. The highest hardness and depth penetrations were obtained when the highest plasma densities were used to carry out the treatments.

Keywords : Microwave plasma; Nitriding.