Mica: a traditional material for the electrical industry

From a large number of natural types of mica, only two can be considered for technical requirements: muscovite and phlogopite.

Mica: a traditional material for the electrical industry

Mica is one of the materials used in electrical engineering that can be found in many electric motors, generators and transformers. Particularly in highly stressed areas: high voltage and high temperature.

What is mica

Mica is so named because of its shimmering and shiny appearance. The different types of mica can easily be distinguished by their color. Muscovite mica is light in appearance and phlogopite mica is dark in appearance. Mica, also called mica, is a mined mineral. It belongs to the monoclinic crystal system and consists of alkali-containing aluminum silicates of various compositions.

From a large number of natural types of mica, only two can be considered for technical requirements: muscovite and phlogopite.

Muscovite, also called potash mica, is a potassium-aluminum double silicate. Muscovite mica is available in different colors: The color is ruby ​​red, also white, green, or brown.

Phlogopite, also called magnesia mica, is a potassium-magnesium-aluminum-iron double silicate. Phlogopite mica essentially comes in one color: the color is similar to amber, which is why it is also known as amber mica.

History of mica

Mica was mentioned as early as 1546 by the mineralogist Georgius Agricola. Where mica was readily available and at reasonable prices, while glass was too expensive, the mineral was used for window panes, especially in rural areas.

Im 20. In the 19th century, mica was first examined using X-rays by Charles-Victor Mauguin. Glimmer means weakly glow or shine.

But since time immemorial, the name has meant a blender that doesn’t keep what it promises. Therefore, some types of mica are pejoratively referred to as cat silver or cat gold. In English the mineral is called mica, from Latin. mica = crumbs (frequent occurrence in small leaflets) or to flash = funkeln.

Occurrence of mica

Mica can be found almost all over the world, but it is worthwhile to mine in India, South Africa, Latin America and Russia, where it is embedded in blocks or plates in the primary rock.

Properties and technical data of mica

Physical properties of mica

Mica has very good electrical insulation and good thermal conductivity properties. But also very good creepage and dielectric strength. Dielectric constant 5 … 8

Mechanical properties of mica

Mica are silicates, i.e. silicon compounds. Mica always have two-dimensional layer structures. Strong binding forces act within the layers, but the layers are weakly bound to one another. This explains the good splitting ability.

Application of mica

Because of its properties mentioned above, mica is an ideal insulator for mounting power transistors on cooling plates. It is also used as an insulator holder for heating elements because of its heat resistance.

The HF values ​​are also remarkable, which is why it is used as a dielectric in high-quality high-frequency capacitors. In the insulation system of high-voltage machines, various components are used that must be optimally matched to one another. High-quality mica products (mica tapes and mica plates) are used as main and partial conductor insulation.

Main uses for components made from mica can be found in the following areas:

  • Construction of induction, arc and high frequency furnaces
  • High voltage applications
  • High temperature applications
  • Sealing industries (e.g. oil & gas distribution)
  • Heating elements for electrical and thermomechanical applications

Delivery forms of mica

We deliver tapes and laminates Mica paper as well as milled and turned parts from mica sheets. The laminates made of mica paper are made from combinations of fiberglass, Polyimidfolien, and Polyester film manufactured using different adhesive systems.

We also manufacture Tubes of mica.

Tests for mica

At the customer’s request, we carry out specified electrical, mechanical and optical tests on mica products such as milled parts or strips.

Disposal of mica

The disposal of mica is unproblematic.

8 properties of mica

8 properties that make mica stand out:

  • High dielectric strength
  • High dielectric resistance
  • Low dielectric losses
  • High temperature and thermal shock resistance
  • Good transparency or optical purity
  • Acid and oil resistance
  • Mechanical cleavage down to the µm range
  • Good workability

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