ACKNOWLEDGEMENT:
Figure
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Source of Figure
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Figure 7
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http://pixshark.com
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Rusting of Iron:
Rusting of Iron is the process in which iron is oxidized to
iron oxide in the presence of oxygen and water.
Figure 6:
Oxygen and moisture both are present in the air and thus
rusting of iron is inevitable. Rusting is an environmental menace and poses a
great threat to all iron structures and parts used in cities, machineries,
plants, etc.
Prevention of
rusting:
Iron can be protected from rusting by eliminating either one
of the factors shown in Figure 6.
Figure 6:
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Table 4 shows some of the techniques employed to prevent
rusting of iron.
Table 4:
Technique
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Rusting Factor Eliminated
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Reasoning/ Explanation
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Painting
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O2 and
H2O
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A layer of paint
prevents iron from rusting by eliminating off its contact with both
atmospheric oxygen and moisture.
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Greasing
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O2 and
H2O
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A layer of oil
and/or grease prevents iron from rusting by eliminating its contact with both
atmospheric oxygen and moisture.
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Plastic coating
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O2 and
H2O
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Plastic coating
iron material eliminates its contact with atmospheric oxygen and moisture to
prevent rusting.
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Galvanizing
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O2 and
H2O
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Zinc is used to
galvanize or coat the iron surface to prevent it from rusting by eliminating
its exposure to atmospheric oxygen and moisture.
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Sacrificial
protection:
Sacrificial protection is another technique employed to
prevent the corrosion of iron. In this technique, a more
reactive metal; usually magnesium or zinc is attached to the iron structure
using wires. Magnesium or zinc being more reactive than iron, oxidizes in
preference to iron, thus preventing iron from rusting.
Magnesium or zinc blocks have to be periodically replaced to
ensure the protection of iron.
Example:
Underwater pipes have magnesium attached to them to
sacrificially protect the iron structure.
Figure 7:
