A phenomenological model of nanocrystalline coating production using the Plasma Electrolytic Saturation (PES) technique

The Plasma Electrolytic Saturation (PES) technique is a relatively new process, which uses a high DC voltage power supply with a related organic electrolyte. Within the phenomenological model, the mechanism of the nanocrystalline coating formation processes has been developed to clarify the controlling variations of the procedure. Within the informative model, a feedback parameter for the formed surface state estimation was established. This parameter is the power spectral density of the current. The voltage versus current characteristics of the treatment within the plasma region depend on the main electrolysis conditions, such as current density, electrolyte concentration and agitation rate. Application of the control algorithm of the parameters could increase the efficiency of the plasma electrolytic saturation and nanocrystalline coating formation. In this process, the electric field strength, E, within the surface region reached a value of between 106 and 108 V/m, which was sufficient for initiation of ionization processes in the vapor envelope. The ionization phenomena initially appeared as a quick sparking in scattered gaseous bubbles and then transformed into a uniform glow distributed throughout the vapor plasma envelope. Because of the hydrodynamic stabilization of the vapor envelope in the region of 180-210 V, the current dropped and the glow discharge transformed into intensive arcing, accompanied by a characteristic low-frequency acoustic emission. © Sharif University of Technology, February 2009.