Development of Advanced Sealing Concepts for Gas Turbines

Increasing gas turbine inlet temperatures in combination with intended reduced efficiency losses due to leakages initiated the work on advanced shroud-less sealing concepts for the high pressure turbine. A summary of the development at the IEK-1 in close cooperation with Rolls- Royce and other partners will be described.

This development started with the evaluation of a sinter-resistant spinel based oxide ceramic with a moderate thermal conductivity and included aspects such as powder design and DoE applied to the spraying method. The optimization led to coating systems with excellent sintering resistance even well above 1300°C and unique incursion as well as thermal shock behavior. An important requisite for these promising results was the use of a 3D- modified interface structure.

In the following studies the oxidation resistance of the coating system was optimized and the degradation mechanisms investigated to improve the long term behavior of the sealing system. Already in an early stage of the development the coatings were applied to engine components which were successfully tested in demonstrator engines. Finally the powder and coating know-how was transferred to industrial suppliers and a rig for the thermal cycling of abradable seal coatings on test parts and components installed.