Effect of H₂ combustion on the stability of thermal barrier coating systems in the hot gas path of turbine engines

The combustion of hydrogen (H₂) as a pure fuel gas or as an additive has been identified as a sustainable solution for reducing CO₂ emissions from conventional fossil fuels and as a strategy for reducing the current economy's dependence on hydrocarbon fuels. Another advantage of using H₂ as an energy carrier is that it can be used as an energy storage medium. However, the combustion of pure hydrogen or gases with high hydrogen content has implications for the corrosion or oxidation of components exposed to the combustion atmosphere. In particular, the combustion of pure hydrogen leads to a significant increase in the water vapor content of the exhaust gas. In modern gas turbines, thermal barrier coating systems are in direct contact with the combustion atmosphere. These protective coating systems consist of a ceramic layer plus a bond coat layer on the metallic components of the turbine. As a result of the increased water vapor content, other oxidation and corrosion products are expected to form on the bond coat and the oxide growth kinetics may be increased, resulting in a reduced lifetime of the turbine components.

However, these changes in the corrosion process and their effects on the component’s lifetime have been hardly investigated to date and are the subject of this project. The aim is to systematically investigate the effects of such changes on the service life of thermal barrier coating systems on rotating and stationary turbine components. For this purpose, the coating systems are exposed to industrial relevant steam atmospheres at high temperatures in various oxidation tests and then characterized in detail regarding their microstructure and mechanical properties. Based on these results, solution strategies will be developed to adapt the bond coats to the changed requirements of hydrogen combustion and optimize their oxidation resistance