Protective coatings play a crucial role for extending the lifetime of components employed in harsh environments as found in aircraft engines. Particularly, new technologies for reducing the CO₂ footprint of aviation generate new material challenges. Lightweight materials, such as γ-TiAl-based alloys and SiC-based ceramic composites, are pivotal in the aviation industry, making protective coatings indispensable but generating new challenges for coating design and processing.

Recent research demonstrates promising protection for γ-TiAl-based alloys through alumina-forming intermetallic coatings based on Ti-Al-Si [1] or Ti-Al-Cr [2] which are applied via physical vapor deposition. However, their brittle nature compromises the mechanical properties. New sputtered coatings made of MAX-phases like Ti₂AlC or Cr₂AlC show promise for protection in high-temperature environments, offering unique nanolaminate microstructures resulting in improved mechanical properties [3].

Future propulsion systems, like MTU's WET engine or systems using SAF fuels based on electrolytically produced H₂, pose additional material challenges due to the highly corrosive water vapor in exhaust gases. Multi-layered environmental barrier coating (EBC) systems, applied by reactive magnetron sputtering, offer a promising solution for sustainable use [4]. Figure 1 displays an exemplary multilayer coating with a Si-based intermetallic adhesion bond coating for oxidation protection and Yb-Si-O based top coating for corrosion protection in water vapor atmospheres.

For achieving higher thermal efficiency, materials used in jet engines shall allow higher temperatures, necessitating novel alloys like Mo-Si-Ti. While these alloys provide high melting point and creep resistance, their poor oxidation behavior requires protective coatings. Silica-forming coatings, along with a CTE-matched graded Mo-Si interlayer, present an opportunity for improved oxidation resistance up to 1200°C that also prevent detrimental pesting [5]. Such multilayer and graded coating systems were processed at DLR with a multi-source magnetron sputtering system in a one-batch process. A combinatorial approach is facilitated by placing components at different positions in the coating chamber that offers a promising way for rapid material development.

The presentation will give a focused overview on recent research in the development of those new coating systems for materials in aero engines, addressing main material and processing issues and contextualizing achieved results.