MODIFICATION OF MECHANICAL AND CHEMICAL SURFACE-PROPERTIES OF METALS BY PLASMA IMMERSION ION-IMPLANTATION

Plasma immersion (ion) implantation (PII) was developed a decade ago f or modifying mechanical and chemical surface properties of metals. In analogy to conventional beam-line ion implantation, it uses energetic ions, mostly nitrogen, that are implanted in the near-surface region o f a material. A sample is enveloped by a plasma and subjected to negat ive high-voltage pulses. In the electrical held, the ions are accelera ted to high energies and incorporated into the sample. This process ta kes place at all sides of the sample simultaneously without requiring ion beam and sample manipulation, in contrast to beam-line ion implant ation. The present review discusses the fundamentals of PII and its mo st important features. The influence of the most important process par ameters such as implantation dose, ion density, pulse repetition rate, and sample temperature on hardness and wear resistance and on corrosi on resistance of metals and alloys such as mild steel, stainless steel , nickel, aluminium and titanium alloys is discussed. (C) 1998 Elsevie r Science S.A.