Combination of different plasma assisted processes with pulsed d.c.: cleaning, nitriding and hardcoatings

Abstract

Pulsed d.c. for plasma activation could open new applications for special surface treatments. Compared with the use of straight d.c. the variability of different processes could be improved. Plasma nitriding and plasma assisted CVD coatings are already known applications. For plasma assisted cleaning and PVD processes the use of pulsed d.c. also has advantages. Separate devices are necessary for each process. For surface treatments of steel special process developments were made, so that the combination of different processes in the same plant without interruption and transport to another plant are possible. A special system is described in which the three steps of surface cleaning and activation, plasma nitriding, and plasma assisted CVD can be realized within a complete closed process. Many problems, such as interactions with the atmosphere, could be eliminated by this combination within the same unit. Results for tribological applications on steel surfaces are presented.