Intensified plasma-assisted processing: science and engineering

Intensified plasma-assisted processing (IPAP) is a surface modification technique developed in our laboratory that has been mainly utilized for low-temperature, low-pressure nitrogen diffusion treatments. Plasma intensification and energetic flux bombardment of the work piece is accomplished by using a triode glow discharge. Our studies show that IPAP can achieve enhanced plasma nitriding kinetics at relatively low temperatures (typically <500degreesC) even in systems that are difficult to nitride by conventional means. IPAP employs high cathode currents at low pressures, allowing enhanced flow and controlled energies of the particles bombarding the work piece leading to formation of desired nanostructured nitrides and deep diffusion zones. A summary of our present understanding of the fundamentals behind this technique is presented, in view of previous and new experimental results and theoretical predictions. Experimental results from several important engineering systems are presented (Ti-, Al-, Ni-base alloys, stainless steels, etc.) where significant improvements in surface-sensitive properties have been achieved. The results to date demonstrate that IPAP is an emerging surface engineering technique of high potential for a wide range of engineering applications. (C) 2002 Elsevier Science B.V. All rights reserved.