Development of thermal barrier coatings by plasma electrolytic oxidation

Aim of the Project 

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.

The aim of this IGF-AiF research project is the development of an economically attractive thermal barrier coating system for titanium materials used in gas turbines by means of plasma-electrolytic oxidation (PEO) technique. Within this plasma-electrochemical 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 below 1 Wm^-1K^-1 with good adhesion properties.

In order to meet the project objectives, suitable ZrO₂ containing electrolytes are to be developed and an adequate PEO process for low and high frequencies or duty cycles is to be designed. 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.

Das IGF-Vorhaben Nr. IGF 21392 N der Forschungsvereinigung DECHEMA e.V. wird über die AiF im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung (IGF) vom Bundesministerium für Wirtschaft und Klimaschutz aufgrund eines Beschlusses des Deutschen Bundestages gefördert.