There are multiple consequences of corrosion that
exist and many times the effects of corrosion is more severe and devastating
that simple material losses. In many cases due to corrosion many of the parts
have to be replaced even if there is a small amount of metal corroded away, it
is because of this that many companies spend a huge amount of money on the
prevention of corrosion and the replacement of such parts; the annual amount of
money that is spent in order to battle the effects of corrosion is more that
$276 billion in the US alone. The effects of corrosion are as listed:
Reduction in the
materials thickness that can result in reduction of mechanical strength and if
not taken care of it will result in failure.
Loss of life or
injuries that may arise in case there is a serious structural failure.
For goods that
are sold for cosmetic purposes, corrosion can cause their appearance to
deteriorate resulting in reduction of price at which they are sold.
Loss of time as
the machinery is repaired and cannot be used in that specific time.
Damage to valves,
pumps, etc. as small metal particles move through them causing them to corrode
from the inside
There is an added
complexity in designing the machinery, as it has to be designed so that there
is minimum amount of corrosion and so that parts could be easily replaced.
For the case of properties of the metal corrosion can:
thickness results in decreased strength.
As for the effects of corrosion, corrosion prevention
techniques are applied in order to minimize the effects of carrion so that the
part could be used for a longer duration of time. Methods for prevention of
corrosion are classified into the following categories.
Change of design.
Modification of material
Corrosion can be controlled by complete or partial
change in the material used. Modification can be done by using one of the two
Coating the metal
with a corrosion resistant coating, which can be either another metal,
protective coating, derived from the metal itself, coating it with an organic
metal to produce a corrosion resistant alloy such as stainless steel.
Alteration of environment
Removal of oxygen.
inhibitors (cathodic, anodic, mixed inhibitors).
Make the fluid
passing through pipes be at lower temperature and velocity.
As corrosion is an electrochemical process, therefore
the rate at which it occurs could be controlled by passing an anodic or
cathodic current. One of the following methods can do this:
Barrier films are protective coatings that isolate the
metal from the corrosive environment; this protective coating doesnot provide
any mechanical properties to the material however, for long time use barrier
films provide the best protection under severe chemical conditions.
Some barrier films/Coverings are given below;
Design of structure
By changing the design of the structure we can minimize
the amount of corrosion that takes place, design measures include:
retention in any part of the device.
between different metals.
of venerable parts.