Novel Thermal Barrier Coatings with Polymer-Derived Ceramic interlayers for jet engine critical components

The commercial aviation industry has a large overall impact on environmental pollution, and therefore more environmentally friendly technologies are needed, as stated in the “Flightpath 2050”, which was passed by the European Union a couple of years ago. Material science solutions include high-temperature light-weight materials, such as the so-called titanium aluminide (TiAl) alloys, since their implementation could lead to substantial weight savings compared to the state-of-the-art Ni-based superalloys and therefore less fuel consumption and reduced emissions.

Motivated by this background, the key novelty of this project is the adaption of the commercially-accepted, state-of-the-art coating concept for Ni-based alloys, consisting of a bond coat and a ceramic thermal barrier coating (TBC), to the much lighter TiAl-based alloys. Substitution of heavier Ni-based alloys by TBC-coated TiAl turbine blades would lead to incredible weight savings and therefore to a much more efficient turbine design. Since TiAl-based alloys suffer from insufficient oxidation resistance at high temperatures, coatings are needed in order to enable their implementation in hotter stages of today´s turbine engines. A SiAlOC polymer-derived ceramic (PDC) coating will not only ensure the desired oxidation resistance due to the formation of a thin Al₂O₃ layer during high temperature exposure, but will also act as a “bond coat” for the outermost TBC layer, which consists of yttria stabilized zirconia (YSZ). The commercial GE-TiAl alloy (Ti-48Al-2Cr-2Nb in at.%) is used as the main base material. In contrast to already existing studies dealing with the deposition of YSZ as a TBC on TiAl, the deposition of PDC is believed to be able to resolve the critical points mentioned in the literature.

Das IGF-Vorhaben wird durch das Bundesministerium für Wirtschaft und Klimaschutz aufgrund eines Beschlusses des Deutschen Bundestages gefördert.