Microwave ECR plasma nitriding of AISI 4140 steel

Camps, E,; Escobar-Alarcón, L.; Chirino, S.; Mejía-Hernández, J. A.; Camps, E,; Escobar-Alarcón, L.; Chirino, S.; Mejía-Hernández, J. A.

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Superficies y vacío

Print version ISSN 1665-3521

Superf. vacío vol.18 n.3 Ciudad de México Sep. 2005

Articles

Microwave ECR plasma nitriding of AISI 4140 steel

E, Camps¹⁴

L. Escobar-Alarcón¹⁴

S. Chirino¹²

J. A. Mejía-Hernández¹³

^¹Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado postal 18-1027, México DF 11801, México.

^² Facultad de Ingeniería, Universidad Autónoma del Estado de México, Toluca, Estado de México, México.

^³ Instituto de Investigaciones en Materiales, UNAM, Apdo. Postal 70-360, 04510 México DF, México.

^⁴ Facultad de Química, Universidad Autónoma del Estado de México, Toluca, Estado de México, México.

Abstract

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

Acknowledgements

Authors wish to thank CONACYT for its partial support under contract 46344.

References

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Received: May 30, 2005; Accepted: August 31, 2005

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