Insulation properties of alumina ceramics
Time: 2019-01-19 Writer: mingrui
Insulation properties of alumina ceramics
97 alumina ceramic insulation abstract: 97% alumina ceramic is a kind of excellent electrical insulation materials, high volume resistivity, specified in the national standard GB/T5593-1999, 100 ℃, rho argument Ω 1 x 1013 cm or more;300 ℃, rho argument Ω 1 x 1010 cm or more;500 ℃,
1, the volume resistivity nu of the volume resistivity insulating material refers to the ratio of the direct current field intensity in the direction of the volume current of the sample to the current density there.Rho argument = EV/jv (Ω cm), type of EV for dc field intensity, the jv for the current density.97% alumina ceramic is a kind of excellent electrical insulation materials, high volume resistivity, specified in the national standard GB/T5593-1999, 100 ℃, rho argument Ω 1 x 1013 cm or more;300 ℃, rho argument Ω 1 x 1010 cm or more;500 ℃, rho argument Ω 1 x 108 cm or more.In fact, the volume resistivity of 97 porcelain produced in China is 1-2 orders of magnitude higher than the above provisions.Instruments for measuring volume resistances are usually high-resistance meters.
Alumina ceramics
Dc breakdown strength the dc breakdown strength of electrical insulating materials refers to the change under the action of external dc electric field, which is mainly caused by the change of internal structure.When the electric field intensity reaches a certain value, it will promote the further change of its internal structure and cause insulation breakdown.National standard GB/ t5593-1999 stipulates that 97% alumina ceramics are subjected to voltage withstand test under dc condition. When dc voltage is applied on the sample, the sample will be broken down. The ratio of the breakdown voltage value to the average thickness of the sample is called dc breakdown strength, unit: KV/mm.The national standard GB/ t5593-1999 stipulates that it should be greater than 18KV/mm.In fact, we can generally achieve 30-40kv /mm.
1. Dielectric constant insulation material is a parameter of the dielectric polarization degree under the alternating current field. It is the ratio of the capacitance of capacitors filled with some insulating material and capacitors of the same electrode size when vacuum is the medium.It represents an inherent property of the material.When the test frequency is 1MHz, the dielectric constant of 97% alumina ceramics is between 9-10.
dielectric loss Angle tangent value dielectric loss means that under the action of the ac electric field, polarization or absorption of the material occurs, resulting in the loss of electrical energy, usually on the dielectric material there is a phenomenon of heat.The dielectric loss is expressed by the tangent of dielectric loss Angle.According to the national standard GB/ t5593-1999, when the frequency is 1MHz, 97% alumina ceramics are required to reach 4 10-4.
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