The major objective of the TOPPCOAT project was the development of improved TBC systems using advanced bonding concepts in combination with modified and advanced microstructures. The first specific objective was to use these developments to provide a significant improvement to state-of-the-art APS coatings and hence provide a cost effective alternative to EB-PVD. In particular, 3D profiling was also investigated as a method to improve the TBC bonding and to control the microstructure and the location of segmentation cracks within the TBC layer.

Advanced spraying techniques either to deposit coatings showing strain compliant columnar structures similar to those of EB-PVD or to initiate the segmentation cracks have been developed in the frame of this project. From the outcomes of a preliminary screening testing activity, the most promising TBCs systems (3D interface, segmented, highly segmented APS, PS – PVD^TM TBCs), have been identified and have been subjected, together with two state of the art coatings (Standard porous APS and columnar EB-PVD), to a wide characterisation activity comprising long (24 hours) and short (2 hours) cycle high temperature oxidation, burner rig testing and thermo-physical characterisation.

In this work a summary of the main outcomes is presented. In particular, for cyclic furnace testing, failure times as a function of the different testing conditions (i.e. cycle duration and testing temperature) will be compared. The TGO growth rates estimated starting from TGO thickness measured at different ageing times will be used to estimate average bondcoat temperatures during burner rig testing and the outcomes will be compared to the computations performed considering as input thermo-physical properties of both TBC and metallic substrates and the testing conditions in the burner rig. Furthermore, since erosion can be an issue, depending on the specific operating conditions, the high temperature solid particle erosion resistance of the different TBC systems have been performed and results will be presented.