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Silicon (Si) is
produced from quartz (SiO2),
through an apparently very simple
chemical reaction:
SiO2
+ C ----> Si + CO2
This reaction
requires the massive use of
electricity, which gives to the
transformation process its name of
electrometallurgy. Quartz and the
carbon reducing agents (wood, coal,
coke, charcoal, electrodes) are put
in an oven heated at very high
temperature (>20000C) by
means of an electric arc created
through electrodes. The metal is
then cast, cooled and adapted
according to the refining,
granulometric and packaging
specifications.
Silicon steel is
undoubtedly the most important soft
magnetic material in use today.
Applications vary in quantities from
the few ounces used in small relays
or pulse transformers to tons used
in generators, motors, and
transformers. Continued growth in
electrical power generation has
required development of better
steels to decrease wasteful
dissipation of energy (as heat) in
electrical apparatus and to minimize
the physical dimensions of the
increasingly powerful equipment now
demanded.
In iron & steel
metallurgy, silicon is used to
produce special up-market steels.
Silicon steel is undoubtedly the
most important soft magnetic
material in use today.
Relay steels contain
1.25 to 2.5% Si, and are used
in direct current applications
because of better permeability,
lower coercive force, and freedom
from aging. Oriented silicon steel
is more restricted in composition
than non-oriented varieties. The
texture is developed by a series of
careful working and annealing
operations. To avoid the y loop of
the Fe-Si phase system, today’s
commercial steel has about 3.25%
Si. Non-oriented grades contain
between 0.5 and 3.25% Si plus
up to 0.5% Al, added to
increase resistivity and lower the
temperature of primary
recrystallization.
The presence of Si
also enhances tensile strength and
creep resistance at elevated
temperature. It does provide
springness in steel. The other Si
bearing steels are rail steel,
spring steel and high tensile steel.
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