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The use of a DC glow discharge source with controlled plasma potential in plasma immersion ion implantation processing has been studied. The characteristics of the discharge source include medium densities, low temperatures, stable continuous DC operation and can be built inexpensively. A tridimensional implantation was realized when the plasma potential is held below 70 V. The plasma density of the discharge source has also been found to be linearly dependent on the potential.

A combined surface modification treatment consisting of ion nitriding at high pressure and high temperature, followed by a cycle at low pressure, both cycles using a gas mixture of (N[sub 2]/H[sub 2]):(50/50) in pressure, was applied to stainless-steel AISI 304. In the first cycle, in a glow discharge at 4×10[sup -1] mbar and temperatures of 400–450 °C, high-pressure nitriding was applied to the samples. In the second cycle, in a glow discharge at 8×10[sup -4] mbar, low-pressure nitriding was applied to the samples. Applying this sequential hybrid treatment alternately, good nitriding was obtained. X-ray diffraction (XRD) measurements showed the effects of this hybrid ion nitriding in the AISI 304 surface, indicating thick nitrided layers, confirmed by Auger electron spectroscopy (AES). Conversion electron Mössbauer spectroscopy, combined with AES and XRD, showed phases and compounds induced by such treatments. Vickers hardness measurements showed great enhancement in the surface hardness. Applying other combinations of gas mixtures and cycles, produced diverse results in the surface, like the induction of α- and ε-phases. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]