The work described in this thesis is an analysis of the Plasma Source Ion Implantation
(PSII) process. A metal target is placed within a plasma, and pulsed to a high negative
potential (10 - 50 kV). The electrons in the plasma close to the target are then repelled
very rapidly, leaving an area of uniform positive charge. This causes an electric field to
be set up between the plasma and the metal target. The ions close to the target are then
accelerated towards the target by the electric field. The ions reach the target at high
velocities, and implant deeply into the metal (-5 x 10-8 m), and form nitrides, which pin
dislocations within the metal's atomic structure. The strength of the metal is therefore
increased, and other properties such as the corrosion resistance of the metal are also
improved. Metals that have undergone the PSII process have widely diverse
applications. For example, in the motor industry, ion implanted metal punches last
much longer than nitrided punches, while in the medical industry ion implanted metals
are used for artificial limbs.
A combination of a number of different analytic, numerical and simulation models are
used to describe the PSII process, including the plasma behaviour and final nitrogen
implantation profile in the metal target after the application of the voltage pulse. In all
cases, a specific attempt has been made to realistically describe as closely as possible,
the actual experimental arrangement at the University of Natal. For example: a
waveform with a fast rise time, short plateau and exponential decay was used; the
nitrogen plasma was more realistically described by a two species fluid to account for
the measured N+, N; mix; and finally, the actual atomic composition for 304 stainless
steel was used in the TAMIX particle simulation.
This work thus models the whole PSII process, and could form the basis of future
studies for the optimisation of the process. / Thesis (M.Sc.)-University of Natal, 1993.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/5068 |
| Date | January 1993 |
| Creators | Thomas, Kim. |
| Contributors | Alport, Michael J. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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