Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Abstract

To increase the lifetime of rocket combustion chambers, thermal barrier coatings (TBC) may be applied on the copper chamber wall. Since standard TBC systems used in gas turbines are not suitable for rocket-engine application and fail at the interface between the substrate and bond coat, a new bond-coat material has to be designed. This bond-coat material has to be chemically compatible to the copper substrate to improve the adhesion and needs a coefficient of thermal expansion close to that of copper to reduce thermal stresses. One approach to achieve this is to modify the standard NiCrAlY alloy used in gas turbines by adding copper. In this work, the influence of copper on the microstructure of NiCrAlY-alloys is investigated with thermodynamical calculations, optical microscopy, SEM, EDX and calorimetry. Adding copper leads to the formation of a significant amount of \(\beta\) and \(\alpha\) Reducing the aluminum and chromium content leads furthermore to a two-phase fcc microstructure.

Keywords

• thermal barrier coatings
• CuNiCrAl
• rocket engine
• copper nickel chromium aluminum
• CTE
• Thermo-Calc