Technical ceramics
DEFINITION
Ceramic materials are inorganic and non-metallic.
Usually they are shaped from the "green body" at room temperature and acquire their typical properties during a sintering process at high temperatures.
Technical Ceramics means ceramic products made for technical application.
The use of technical ceramics in a large application field is justified by the diversity of properties offered by materials used for parts manufacturing.
Examples of technical ceramic materials:
| Alumina | AI203 |
| Silicon nitride | Si3N4 |
| Zirconia | Zr02 |
| Aluminium nitride | AIN |
| Magnesium oxide | MgO |
| Boron nitride | BN |
| Silicon carbide | SiC |
| Perovskites |
The choice of the material depends on properties it brings to the final part:
- Thermal properties
- Mechanical properties
- Electric properties
There is also another range of materials used for parts asking less severe stress:
- Mullite
- Cordierite
Main ceramic groups
In accordance with their chemical composition the technical ceramic materials can be divided into main groups:
The material of this group consist 90% of single phase and single component metal oxides.
Synthetic raw materials with a high level of purity lead to an even structure with very good properties at a very high sintering temperature.
Ceramic materials compounds of silicon and aluminium with nitrogen or carbon belong to this group.
In general nonoxide ceramics demonstrate a high share of covalence bonding which provides them with very good mechanical properties, even when being used at high temperatures. Amongst nonoxide ceramics are:
These materials combine the basic electrical, mechanical and thermal properties of technical ceramics
Fundamental ingredients of this multi-phase material are clay, kaolin, as well as feldspar and soapstone as silicate carrier. Further ingredients such as alumina and zirconia (ZrSiO4) are added to achieve specific properties.
These materials are sometime used for special applications like nozzle casting, ionic conductors….
