6103.1:
Nano-scaled PVD-seeding of in-situ thermally grown alpha-alumina for extended life of high temperature TBCs
Abstract
Thermal barrier coatings (TBCs) are applied on high temperature engine components to extend service temperature and life. Current understanding of TBCs suggests that life is determed by the formation of a thermally grown oxide – TGO - between the metallic bond coat and the ceramic top coat of the TBC-system. Under service conditions, the oxide that naturally forms first is a cubic ã -Al2O3 with a relatively open structure and a high oxygen diffusivity.
One way to reduce the growth rate of this TGO could be to induce the formation of hexagonal á -Al2O3 which has an intrinsically lower diffusivity. This may be done by creating nano-clusters of á -Al2O3 on the surface of the bond coat to act as nuclei for further growth. The striven size shall lie in the range of 10 nm.
The goals of this project are:
1. To use PVD-technology to deposit nano-scaled á -Al2O3 seeds on the bond coat surface.
2. To investigate how the seeded surface influences the growth of the TGO.