Hybrid processes based on plasma immersion ion implantation: A brief review

Hybrid processes based on plasma immersion ion implantation (PIII) are discussed in this paper. The thin modified layer produced by ion implantation has hampered a wider acceptance of the PIII technology, and in order to achieve thicker layers suitable for harsh environment to withstand severe wear, corrosion, etc., we have investigated several hybrid processes combining PIII and other techniques while taking advantaging of the unique capability of not needing to break vacuum in between processes using the PIII facility in the City University of Hong Kong. For instance, a relatively thick wear-resistant and corrosion-resistant layer composed of expanded austenite has been produced on stainless steel using low-voltage, elevated temperature plasma ion implantation. The processing efficiency is determined by many factors such as the treatment temperature, working gas pressure, implantation voltage, and whether or not active metal ions are introduced into the plasma. The combination of plasma implantation and deposition is a versatile tool to fabricate the films with unique properties. The surface properties are observed to be very much dependent on the implantation parameters. For illustration of the versatility of hybrid processes, diamond-like-carbon (DLC) films are synthesized using several techniques such as carbon vacuum arc and direct high-voltage glow discharge with or without the assistance of external plasma sources.