Chemistry Reference
In-Depth Information
TABLE 8.9
Plasma Electrolysis Uses Different
Electrolyte Compositions for the
Various Applications
Oxidation
Na
2
SiO
3
/KOH
Nitriding
NaNO
3
Carburizing
C
3
H
5
(OH)
3
/Na
2
CO
3
Boriding
Na
2
B
4
O
7
/NaOH
boriding need treatment times of some minutes for formation of 200-500 μm thick
compound/diffusion layers.
Plasma electrolytic procedures can also be used for plasma polishing [180]. The
work piece operating as anode in the electrolyte is covered by a thin gas layer where
plasma is ignited for sufficient high voltages. Polishing may be caused by
•
Peaks and other roughness that are etched by chemical and plasma chemical
effects
•
Surface areas that are oxidized and reaction products that are dissolved
Roughness lower that 0.1 μm can be achieved. Stainless steel, Ti and Ti-alloys, and
copper were successfully plasma polished.
Atmospheric pressure plasmas caused by their etching properties are also reliable
for plasma polishing [181-183].
8.2.3.3 Textiles
It has long been known that the surface modification of natural substances can
be achieved using plasma technologies [184]. Numerous publications to date have
documented the tremendous scientific interest in the processes that take place. Now
the textile industry too is showing interest in plasma technologies. The potential to
save chemicals and energy as well as environmental aspects like the reduction of
sewage load are strong propulsions.
The spectrum of applications of plasma technologies in the textile industry ranges
from the functionalization of fiber surfaces up to the production of special lay-
ers. Surface properties like wettability, refractability, colorability, and printability
or surface hardness can be influenced without changing the bulk qualities of the
substrate [185].
An extensive topical overview of present plasma technologies in the textile indus-
try including possibilities and limitations as well as further developments is given in
[186,187] (see Table 8.10).
This section shows that atmospheric pressure discharges are recommended for
fields of application that were reserved for low-pressure plasma methods just a few
years ago.
