| What is MICA? The dictionary defines
mica as "A class of silicates having a prismatic angle 120o, eminently perfect
basal cleavage, affording thin tough laminate or scales, colorless to jet black,
transparent to translucent, of widely varying chemical composition, and crystallizing in
the monoclinic system".
In brief, mica is a
generic term applied to a group of a complex alumina-silicate minerals having a sheet or
plate like structure with different chemical compositions and physical properties. All
micas from from flat six-sided mono-clinical crystals with a remarkable cleavage in the
direction of the large surfaces, which permits them to split easily into optically flat
films, as thin as one micron in thickness. When split into thin films, they remain tough
and elastic even at high temperature.
What makes MICA so
important to command such a unique position? Because it had been gifted with exceptional
values. MICA possesses some of the most outstanding combination of chemical, physical,
electrical, thermal and mechanical properties which are not found in any other product.
Physically: Mica is transparent, optically flat, easily splittable into thin
films along its cleavage, colorless in thin sheets, resilient and incompressible.
Chemically: Mica is a complex hydrous silicate of aluminum, containing
potassium, magnesium, iron, sodium fluorine and/or lithium and also traces of several
other elements. It is stable and completely inert to the action of water, acids (except
hydro-fluoric and concentrated sulphuric) alkalis, conventional solvents, oils and is
virtually unaffected by atmospheric action.
*Electrically:
Mica has the unique combination of great dielectric strength, uniform dielectric constant
and capacitance stability, low power loss (high Q factor), high electrical resistively and
low temperature coefficient and capacitance. It is noted for its resistances to arc and
corona discharge with no permanent injury, and has little or no effect when exposed to
electronic radiation dosages up to 1018 nvt. Thus maintaining its a-c
dielectric material when exposed to the oxidizing action of electrical discharges either
on the surface or within internal gas spaces in built-up mica insulation.
Thermally: Mica is fire proof, infusible, incombustible and non-flammable and
can resist temperatures of 600oC to 900oC (1112oF to 1652oF)
depending on the type of mica. It has low heat conductivity, excellent thermal stability
and may be exposed to high temperatures without noticeable effect.
Mechanically: Mica is relatively soft and can be hand cut, machined or
die-punched. It is flexible, elastic and tough, having high tensile strength. It can
withstand great mechanical pressure perpendicular to plane but the lamination have
cleavage and can be easily split into very thin leaves.
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