Dielectric ceramic is a kind of ceramic material which resistivity is greater than 108Ω∙m, and can withstand the strong electric field without breakdown. The dielectric material is an insulator, putting more emphasis on its polarization characteristics. According to the characters of its dielectric properties can be divided into electrical insulating ceramics, ceramic capacitor, piezoelectric and ferroelectric ceramics. They are usually expressed by volume resistivity, dielectric constant, and dielectric loss.
What is volume resistivity?
The resistance of material per cubic volume, the higher the volume resistivity, materials for electrical insulation components of the higher efficiency.
What is a dielectric constant?
It is used to measure an insulator to store electrical energy performance, it is two pieces of the metal plate with insulation materials as the medium compared with air as medium or vacuum, the ratio of the capacitance.
What is dielectric loss?
Dielectric loss refers to the dielectric under the effect of the alternating electric field, the consumption of electricity per unit time.
Taking the insulating ceramic as an example, we will introduce its properties, classification, and application to better understand it.
Insulation material is not conductive, requiring high resistivity as far as possible. To become an excellent insulating ceramics, must have the following properties:
- Volume resistivity: ≥1012 Ω∙cm
- Relative dielectric constant ≤ 30
- Good thermal conductivity, close to conductor material thermal expansion coefficient, heat resistance, high strength, and chemical stability
Classification of insulating ceramic:
- The oxide, such as Si02, A120, etc
- The non-oxide, such as Si3N4, BN, AIN, etc
- Single crystal insulating ceramics, such as silicon, synthetic mica (the floorboard of the layered structure of aluminum silicate), spinel, synthetic sapphire, etc.
The application of the insulating ceramic:
- High-performance ceramic insulator which can withstand the pressure of more than 500 keV used in extra-high-voltage power transmission.
- Ceramic spark plugs used for automobiles, ceramic ignition needles used for gas stoves
- The substrate used for integrated circuits and packaging materials
- Ceramic insulating tubes are used for electrical and electronic.
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