In order to reduce the kerosene consumption of aircrafts and hence CO2 emissions, the thermal efficiency of turbines is increased by increasing their gas inlet temperatures. However, the high temperatures exceed the application range of the metallic materials used, which is why critical components such as the combustion chamber or turbine blades are provided with a porous ceramic zirconium oxide coating for thermal insulation. Such thermal barrier coatings are very complex and cost-intensive using electron beam evaporation or atmospheric plasma spraying.
Aim of the IGF project, which was started on 1 November 2020 at the DECHEMA Research Institute, is the “Development of thermal barrier coatings on titanium and titanium aluminides by plasma-electrolytic oxidation” (more about the project). The versatile properties of the generated PEO coating are intended to save time and costs for the coating of turbine components and open up a new sales market for small and medium-sized companies in the surface technology sector.
This interdisciplinary project is being worked on across working groups at the DECHEMA Research Institute and should be completed by 31 October 2022.
Within the plasma-electrochemical PEO process, a ceramic conversion layer of the metallic substrate is created in aqueous electrolytes by applying a high voltage between a workpiece (anode) and a cathode. The inherent structure of the crystalline and porous PEO ceramic is used to achieve effective thermal insulation with low thermal conductivity values and good adhesion properties. In order to meet the project objectives, suitable ZrO2 containing electrolytes will be developed and an adequate PEO process for low and high frequencies or duty cycles is to be designed.
Photo credits: © AiF Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ e.V.