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Plasma as "the fourth state of matter"
offers particular advantages for hardening technology. In plasma, the chemical
reactions needed for hardening take place over considerably shorter process
times - and this means savings in time for the customer. Also, the process
responds excellently to controlling parameters, thus giving rise to reproducible
results for generating surface layers optimized for specific engineering
requirements. At the same time both the distortion associated with hardening
and the continued growth of the hardened layer are minimized (in the latter
case to a few micrometres). So cost- and time-intensive finishing
work no longer applies. A further advantage is that the full depth of nitriding
is available - grinding is no longer needed.
Pulse plasma method - excellent response to control
All these are good reasons for the manufacturers of heavily loaded
components to invest in plasma technology for their heat treatment.
The plant built by PlaTeG Plasma Technik Grün GmbH in Siegen utilizes
the pulse plasma method, which generates
plasma as intervalled pulses. This not only ensures that the heat treatment
process responds excellently to controlling parameters, but also prevents
the formation of arcs that can damage the surface of the workpiece. |
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Nitriding, nitrocarburizing,
and anticorrosion treatment
The new plant operates with the reactants nitrogen and hydrogen, whereby
a third reactant of carbonated gas is needed for plasma
nitrocarburizing.
Because the installation is equipped with a conventional supplementary
heater, the process times are reduced even further with respect to a conventional
plasma hardening plant.
Controlled inline oxidation treatment
then provides the parts with an additional anticorrosive coating.
Fig: An example of a plasma nitriding plant. A
much larger system is being installed at present at the Reese hardening
plant in Bochum. |
