Classification of Electrical Engineering Materials

Materials used in the field of Electrical Engineering are called the Electrical Engineering materials. Based on properties and area of applications, Electrical Engineering materials can be classified as below-

1. Conductors
2. Semiconductors
3. Insulators
4. Magnetic material

A classification chart of electrical engineering materials is shown in figure below

Conductors

Conductors are the materials which have very high conductivity. The number of free electrons are very high in conductor at room temperature, which is basic reason of high conductivity of conductors. Examples: Silver, Copper, Gold, Aluminum etc.

The number of free electrons are very high in silver, which makes the silver a best conductors of electricity. The binding force on these free valance electrons by nucleus is very low. Due to which these electrons can be easy freed from the nucleus and can participate in flow of electricity.

Semiconductors

Semiconductors are have the conductivity between conductors and insulators. Semiconductors are the elements of group-III, group-IV and group-IV elements. Semiconducting materials are having covalent bond. At normal temperature the conductivity of semiconductors is very low. With increase of temperature the conductivity of semiconductors increase exponentially. Example: Germanium, Silicon, Gallium Arsenic etc.

Insulating Materials

The conductivity of insulating materials is very low. These material are having very high resistivity which makes them very suitable to insulate the current carrying parts from earthed metallic structure. In insulating materials the elections are tightly bounded with nucleus. Due to which that cannot be freed for movement in materials. Due to which the resistivity of insulating materials is very high. Example:- Plastics, Ceramics, PVC etc.

Magnetic Materials

These materials play an important role for existence of various electrical machines. The magnetic materials having high permeability are used for building the core to from the low reluctance path for magnetic flux. Magnetic materials can be further divided in following categories

• Ferromagnetic materials
• Paramagnetic material
• Diamagnetic materials
• Antiferromagnetic materials
• Ferrites

Ferromagnetic Materials

These materials are having very large and positive susceptibility to external magnetic field. They are having a strong attraction to external magnetic field and are able to retain magnetism even after remove of external magnetic field. This property of materials is called magnetic hysteresis. Example: Iron, Cobalt, Nickel.

Paramagnetic Material

These materials are having very small and positive susceptibility to external magnetic field. In the presence of external magnetic field, these materials attains very small magnetism. Example: Aluminum, Platinum, oxygen, Air etc.

Diamagnetic materials

These materials are having very weak and negative magnetic susceptibility to external magnetic field. On application of external magnetic field these are repelled slightly by external magnetic field. These materials does not retains the magnetism after removal of external magnetic field. Mostly all metals i.e. silver, copper, gold, hydrogen etc. are diamagnetic materials.

Antiferromagnetic materials

These materials are having very small and positive susceptibility to external magnetic field. In the presence of external magnetic field these materials get slightly magnetized in the direction of external magnetic field. In these materials, atoms are having mixed parallel and anti parallel aligned magnetic dipole movement. Example: Cr, MNO, FeO, CoO, NiO, Mn etc.

Ferrites

These materials are having very large and positive magnetic susceptibility like ferromagnetic materials. These materials are generally compound which are having more complex crystal structures than a pure material. As compare to ferromagnetic materials, ferrites are having lower magnetic saturation. Example: Fe₃O₄, BaO.6Fe₂O₃ etc.