Enhanced plasma nitriding at low pressures: A comparative study of d.c. and r.f. techniques

Increasing industrial interest in the use of enhanced low pressure ion plating techniques for surface coating applications led the authors to examine the applicability of discharge enhancement to the plasma nitriding process. The performance of various d.c. diode, triode and r.f. systems is discussed in terms of surface layer growth rate, hardness profiles and coverage uniformity. It is shown that a correlation of visual and optical emission spectroscopy analyses of practical discharges with predictive equations for plasma phenomena can be useful in explaining observed discharge effects, thus assisting development and optimization of the plasma nitriding process.