– Braking systems
Compared to other industries, the aerospace sector makes a rather small contribution to Germany’s gross domestic product. However, precisely in this sector, economically and strategically important technology and know-how are developed that are then utilized in numerous industries and consequently play a key role in assuring industry’s competitiveness.
At the focus of aerospace technology with regards to scientific, technical and environmentally relevant aspects are four system types:
The technical requirements for such systems concentrate on:
- Low weight
- Good aerodynamics
- Efficient drives
- Power supply
- Data transfer and communications
- Thermal and dynamic resistance
From an ecological perspective, key factors are low noise generation and low fuel consumption.
In various positions in these complex structures, the use of components made of high-grade oxide and non-oxide ceramic materials and composites is recommended when high resilience is demanded in sometimes extreme operating conditions.
A rocket used to launch a satellite in orbit around the Earth has to reach a horizontal velocity of at least 7.8 km/s. To exit the Earth’s gravitational field, more than 11 km/s are necessary. Machine and equipment components made of ceramic materials and composite components have to withstand a multiple of the Earth’s acceleration, especially during lift-off, without incurring any damage. Besides the high technical resilience, an exceptionally high reliability of the ceramic components is a core requirement as the failure of even one component, which can be worth several thousand euros, can adversely impact an entire project costing many hundreds of millions of euros, and, in the case of manned space flights, endanger human life.
The use of high-purity, monolithic oxide and non-oxide ceramic materials and composites presents a potential solution when the specific requirements profiles demand the following properties from the components:
- Low density
- High mechanical strength
- High rigidity
- High toughness
- High wear resistance
- Resistance to high and low temperatures over a large range
- High thermal shock resistance
- Phase stability in the applicable pressure and temperature range
- Low thermal expansion
- High or low thermal conductivity, depending on the specific application
- Resistance to cosmic radiation
- High electrical insulating capacity
- Realizability of adhesively bonded, high-vacuum-tight ceramic-ceramic and ceramic-metal composite components also for temperatures near 0 K, with high thermal shock resistance and high mechanical strength
- No gas emission
Depending on the specific application, the requirement profiles are very different, and a correspondingly wide range of suitable high-grade ceramic materials is available for selection: Al2O3, ZrO2, AlN, SiC, Si3N4, ferrites, piezoceramics and fibre composites.
In some cases, the materials are optimized for a specific application and consequently guarantee reliable function in long-term application.
One example is the high-vacuum-tight electric feedthrough fabricated by means of metal brazing used as a component in the “Rosina” spectrometer in the “Rosetta” space probe.