Advanced ceramics offer superior dielectric properties compared to those of metals and plastics. Advanced ceramics are insulating materials: they do not conduct electrical currents. This physical property is called resistivity. Other electrical properties, such as dielectric strength, relative permittivity (or dielectric constant) and the loss angle, vary from one ceramic to the next.
Description
Dielectric strength, also called breakdown strength, is the maximum voltage a material can withstand before generating an electrical arc on the surface or through the thickness of the material. Dielectric strength is measured in Kv/mm.
Advanced ceramics such as high-purity (≥94 %) alumina and aluminium nitride offer this characteristic, and to a lesser extent sintered silicon nitride. Silica, quartz and Macor are also very good insulating materials. Silicone carbides and zirconia do not offer good dielectric strength.
Application markets
These materials are used in a wide variety of business sectors: electronics, defence, medical, energy, transport, aeronautical and spatial, etc.
Comparative table of properties
| Values at ambient temperature – 20°c |
Resistivity (Ω.m) |
Dielectric strength (KV/mm) | Dielectric loss factor (tan ɗ) |
Dielectric constant (K’) |
|
Alumina (94 to 99.8 % ) |
>1012 to 1015 | 17 to 40 |
1,5.10-4 to 3.10-5 |
9.5 to 11 |
| Aluminium nitride |
5.1012 to 1013 |
16 to 20 | 0,5.10-3 | |
| Sintered silicon nitride |
> 1010 to 1011 |
15 | - | - |
| Quartz |
1016 to 1018 |
25 to 40 | 10-3 to 10-4 | 3.7 |
These values are for information only and do not constitute a contractual obligation.