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The
mica is a mineral widespread all over the world,
more often in a mixture with primary rocks.
Exploited deposits of mica are located first
of all in India, on American continent, in a
southern part of Africa and in Russia.
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On
the chemical composition the mica is aluminosilicate.
There are two main kinds of mica:
MUSCOVITE
- K Al2(Al
Si3 O10)
OH2
- at
the preferential contents of potassium. This
is the most widespread material, its title takes
place from a word "Moscow". Large deposits of
mica were exploited near this city in middle
ages. Mica was used instead of glass in that
far time. The muscovite has light colouring,
and on the mechanical properties surpasses phlogopite
(mineral mica).
PHLOGOPITE
- K Mg3(Al
Si3 O10)
OH2
- at
the preferential contents of magnesium has more
dark colouring, and by virtue of the distinctive
chemical properties is more resistant to high
temperatures than muscovite.
Thanking
to a lot of exclusive natural properties the
mica in many cases is an irreplaceable industrial
material:
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THERMAL
PROPERTIES
- Resists
the temperature up to 1000 C°
-
Fire resistance
- Low
thermal conductivity
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- The
electric toughness is higher than 25 kW/mm
- Good
resistance to an arc
- Microwave
permeability
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CHEMICAL
PROPETIES
The
mica is tolerant to the majority of chemical
reagents, such as solvents, acid, bases and
mineral oils
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MECHANICAL
PROPETIES
-
Very
good hardness at contraction
-
Good
hardness at stretching against arcuation
-
High
modulus of elasticity
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The
mineral of mica has the specific characteristic:
it can be slivered for obtaining of very thin
laminas of identical thickness. NMF use high
technologies permitting an agglomeration of
oddments of mica for manufacturing of a homogeneous
material
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