Team High Temperature Protective Coatings

The team focuses on developing materials solutions for protective coatings such as thermal barrier coatings (TBC) and environmental barrier coatings (EBC) for highly thermomechanically loaded components, primarily in stationary and aircraft gas turbines. In order to ensure fast development cycles, special emphasis is given to the assessment of their functionality and lifetime at high temperatures under realistic test conditions (e. g. in burner rig testing).

Advanced multilayered EBCs and TBCs
Starting from the specification and synthesis of new, mainly ceramic materials, components with TBCs and EBCs based on advanced multilayered and/or graded architectures are manufactured. The application of new processing technologies allows for the development of EBC/TBC systems with well-controlled properties in terms of microstructure and local composition. Pyrochlores such as Gd2Zr2O7, complex perovskites or (hexa)aluminates are of particular interest for TBC applications. Due to their relatively low fracture toughness, doublelayer systems (developed at IEK-1) are usually required. Research on EBCs currently focuses on rare-earth silicates and other oxides. For the improvement of adhesion of thick coatings on inhomogeneous substrates such as ceramic matrix composites or abradables, advanced laser surface texturing is employed.

TBCs resistant to molten deposits
An increasingly important aspect at even higher temperatures is the resistance of porous layers against infiltration by calciummagnesium- aluminium silicates (often called “CMAS”). These silicates are present in air as solids and are also produced by abrasion in the turbines. They are deposited on the turbine components and can penetrate the barrier coatings in their molten form. Once they solidify, they cause considerable damage by decreasing the strain tolerance. In addition to the Gd containing pyrochlores, aluminates also show a better stability than YSZ.