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Institute of Energy and Climate Research (IEK)

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Fatigue Group

Gas and steam turbines as well as solid oxide fuel cell (SOFC) systems must provide high reliability during long-term service and need to sustain numerous start-stop cycles and load changes. The latter aspect is essential in the case of aero engines and SOFC systems, but becomes -due to the increasing amount of fluctuating renewable energy based power generation- of increasing concern for gas and steam power plants. Load changes induce time dependent temperature gradients which result in thermo-mechanical fatigue loadings that strongly influence service life of key components, e. g. turbine blades or SOFCs. In case of metal-ceramics compound components, such as turbine blades with thermal barrier coatings or metal-ceramic braze joints in SOFC stacks, the thermal mismatch between metal and ceramics induces a further load component which needs to be considered for design. Furthermore, oxide layers growing on metallic components during high-temperature loading have significant influence on the fatigue behavior.
The working group therefore investigates the isothermal and thermo-mechanical fatigue behavior of metallic high temperature materials and of metal-ceramic compounds for power plants and SOFCs.

Ongoing projects

Thermografische Analyse der Delamination eines TBC-Systems

Ceramic thermal barrier coatings for gas turbine blades

Improvement of the efficiency of stationary gas turbines and jet engines by application of thermal barrier coatings (TBCs).

More: Ceramic thermal barrier coatings for gas turbine blades …

Teaser

Optimization of Thermal-Barrier-Coatings

Influence of bond coat and Al2O3-layer creep strength on the damage of thermal barrier coatings at thermocyclic load.

More: Optimization of Thermal-Barrier-Coatings …

Beschleunigte Rissausbreitung ins Substrat aufgrund der kleinen Verzweigung an der Grenzfläche in einer duplex-beschichteten Probe (Schichtvariante II)  nach Out-of-Phase TMF-Beanspruchung

Ni-base superalloys for land-based gas turbines and aero engines

For more than a decade, the single crystal Ni-base superalloys are widely applied for turbine components in advanced jet engines.

More: Ni-base superalloys for land-based gas turbines and aero engines …

Rasterelektronenmikroskopische Aufnahme einer Ni-Basis Superlegierung

Probabilistic life-time modelling at high temperature fatigue

Probabilistic fatigue life calculation of Ni-base alloys under high-temperature fatigue loadings.

More: Probabilistic life-time modelling at high temperature fatigue …

Schematic presentation of an SN curve for metallic materials with sufficiently large inclusions (≥ 10 μm)

Fatigue behaviour of a steel for low-pressure steam turbine blades at Very High Cycle Fatigue with superimposed high mean stresses

DFG Forschergruppe 1779

Very high cycle fatigue of structured sheets

The reduction of aerodynamic drag of modern transport systems by structured sheets is beneficial for both, ecological and economic reasons.

More: Very high cycle fatigue of structured sheets …

Reactive air brazing to combine metallic and ceramic components

At IEK-2 RAB-brazing is used for several years, to integrate ceramic components into metallic frames for high temperature fuel cell application.

More: Reactive air brazing to combine metallic and ceramic components …

Enclosed research projects

Aluminium cast alloys for high performance pistons

In the course of engine "downsizing", the automotive industry develops more efficient engines with higher power densities. Consequently, the requirements on the used materials increase. More: Aluminium cast alloys for high performance pistons …

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