Project 2: Preparation of ceramic coatings based on ultrahigh-temperature ceramic nanocomposites (UHTC-NCs) from precursors
Ceramics generally stand out thanks to their high thermal and chemical stability. Combined with a low thermal conductivity, these properties allow coatings for super alloys which enable their use at accelerated temperatures. The ceramic layer protects the workpiece from corrosion and lowers the temperature at the surface of the alloy. Thus, higher operation temperatures can be realized. As a result, turbines can run at higher efficiency. The aim of this project is the preparation of thermal protection coatings for applications above 1200 °C in aggressive environments.
Ultrahigh-temperature ceramic nanocomposites based on Si(M)CX will be derived via the polymer derived ceramic (PDC) route from single source precursors developed in Project 1. Syntheses conditions as well as different coating techniques, such as spin coating, dip coating and additive manufacturing, will be optimized for the preparation of thick and crack free ceramic layers on refractory (inter)metallic systems (e. g. Mo-Si-B-X). Structure and properties of the precursors and coatings will be extensively characterized. The performance of the fabricated composites will be tested at high temperatures in hostile environments. Thereby, suitable ceramic/(inter)metallic compositions with optimized structural characteristics and high-temperature capabilities will be identified.
The three doctoral projects in the corresponding phase of the RTG will emphasize on: 1) Synthesis of preceramic polymer precursors for ceramic nanocomposites and optimization of their visco-elastic properties for coating preparation purposes. 2) Fabrication and structural characterization of thick ceramic coatings (> 10 μm) on Mo-Si-B-X substrates. 3) Systematic studies of the high-temperature behaviour of optimized multi-layered ceramic/(inter)metallic systems concerning their long-term operation at temperatures above 1200 °C in hostile environments.