Mica is a mineral having crystalline structure which is able to provide excellent electric properties, heat resistance and physical and chemical properties. Muscovite, phlogopite mica and synthetic mica can be considered as one of the most important insulating materials in modern electrical industry.
Muscovite [KAl2, AlSi3O10 (OH)2] and phlogopite mica [KMg3(AlSi3O10XOH)2] are natural minerals. Crystalline structure of natural mica contains (OH) and begins to fracture at a temperature of 750°C-800°C (muscovite mica) and 850°C-950°C (phlogopite mica), thermogravimetric losses of natural mica increase sharply. Synthetic mica [KMg2(AlSi3O10)F2] is a non-natural mica crystal. Synthetic mica does not contain (OH), and decays at melting point of 1350°C.
Due to special technology, by heating of high-quality muscovite mica to a temperature above 850°C, the calcined muscovite is obtained. Calcined muscovite does not contain water and impurities which adversely affect on dielectric strength and temperature resistance; its chemical properties and physical stability are substantially improved. Calcined muscovite is extensively used for products having rigid requirements to high dielectric strength and high temperature resistance.
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| Muscovite | Phlogopite mica | Synthetic mica | Calcined mica |
| Chemical composition | Muscovite | Phlogopite mica | Synthetic mica |
| Silicone dioxide (SiO2) | 38,2-48,5% | 38,2-45% | 38-42% |
| Aluminium oxide (Al2O3) | 20,8-36,1% | 10,8-17% | 10-14% |
| Potassium oxide (K2O) | 7,32-9,87% | 7-10,3% | 9-14% |
| Iron oxide (Fe2O3) | 1,56-2,48% | ≤0,1% | – |
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Magnesium oxide (MgO)
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≤2,0% | 21,4-29,4% | 24-29% |
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Fluorine (F)
|
– | – | 7-12% |
