|
|
| |
Various raw materials from mining areas in the whole world form
the basis for the production of high-quality oxides and mixed
oxides. Following materials belong to the group
of the oxide ceramics materials:
- aluminium oxide
- magnesium oxide
- zirconium oxide
- aluminium titanate
- piezo ceramic
|
|
 |
ALUMINIUM OXIDE (AL2O3)
Alumina with its Al2O3 content of more
80% to more than 99% is technically the most important oxide
ceramic material. It is characterised by
- a high strength and hardness,
- high resistance to wear and corrosion,
- high thermal conductivity,
- excellent insulation properties,
- high toughness and
- high-temperature strength.
This material is more or less employed in all field of application
because of its many properties and combination of properties
and because of its good price-performance ratio. You will find
it being used in
- electrical engineering,
- in electronics,
- in mechanical and plant engineering,
- in chemical and processing technology,
- in medical technology and
- in high-temperature engineering.
For more detailed examples, see the alphabetical application
list. |
|
|
MAGNESIUM OXIDE (MgO)
This material is mostly produced as high-grade, so called unary
ceramic, in porous or gas-tight form. Special characteristics
are
- the good electrical insulation properties and
- its thermal conductivity.
Magnesium oxide is used
- in heat engineering for the production of tubes with specifically
defined strength, as well as
- in insulation material e.g. casings.
|
|
|
ZIRCONIUM OXIDE (ZrO2)
Zirconia occurs in monoclinic, tetragonal and cubic crystal
modifications and is produced as fully stabilised (FSZ), partially
stabilised (TSZ) or tetragonal zirconia, depending on the dotage
amount.
Zirconias have acquired a new significance in the last years
due to their excellent tribiological properties,
- their high flexura and tensile strength,
- their high fracture toughness,
- their very good corrosion and wear resistance,
- their low thermal conductivity,
- their oxygen ion conductivity and
- their E-module like steel
Due to these properties zirconia ceramics are preferred for
- application in mechanically high-load components.
The oxygen ion conductivity is used for reading oxygen partial
pressures e.g.
- in the Lambda probe in catalysts.
|
|
|
ALUMINIUM TITANATE (AT)
A stoichiometric composed phase of alumina and titania. The
material convinces trough
- its low thermal expansion coefficient,
- combined with a very high resistance to thermal shock,
- low wettability trough aluminium and
- non-ferrous melting and open porosity.
Aluminium titanate is used for example as
- portliners or cylinder linings in motors,
- kiln dampers and in foundries.
|
|
|
PIEZO CERAMIC (PZT)
Today the most important piezoelectrical ceramic materials are
based on the oxide mixed crystals system lead zirconate and
lead titanate. The properties depend on the molar proportions
(lead zirconate to lead titanate), as well as substitutions
and dotage through additional elements. Piezo ceramics are able
to set an electrical charge free during mechanical distortion
or lead, due to the direct piezo-electrical effect. If an inverse
piezoelectrical effect takes place, then there is a change of
dimension through an electrical field. Items there are possibilities
for materials with very different specifications, for example
- sensors,
- high performance ultra sonic generators and
- actuators
|
| Further,
more detailed information to this in the Brevier |
| . |
|
10. Mai 2005
|
|
|
|
|
English