Mica an Introduction
Mica is a generic term applied to a group of Complex aluminosilicate minerals having a sheet or plate like structure with different composition and physical properties. All mica form flat six-sided monoclinical crystals with a remarkable cleavage in the direction of large surfaces, which permits them to easily split into optically flat films. When split into thin films, they remain tough and elastic even at high temperature. Mica possesses some of the most outstanding combinations 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, colourless in thin sheets, resilient and incompressible.
Chemically: It is a complex hydrous silicate of aluminium, 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) alkalies conventional solvents, oil and 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 resistivity and low temperature coefficient and capacitance. It is noted for its resistances to arc and corona discharge with no permanent injury.
Thermally: Mica is fire proof, infusable, incombustible and non- flammable and can resist temperatures of 600-C to 900-C, 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.