TOPPCOATProject ID: 516149
Towards design and processing of advanced, competitive thermal barrier coating systems
The aim of this project is to make significant improvements to thermal barrier coating (TBC) systems used for gas turbine applications by introducing a number of key innovations.TBC's consist of an oxidation resistant (Co,Ni)CrAlY bond coat and a insulat ing yttria-stabilized zirconia top coat. The top coat is deposited by air plasma-spraying (APS) or by electron-beam physical vapour deposition (EB-PVD). The use of the much more expensive EB-PVD process has been due largely to the columnar structure of t he coatings resulting in improved strain tolerance and improved reliability. The in-service life of these coatings is now around 8000 hours. Conventional APS coatings are deposited onto a random, rough grit blasted surface. A new method which produces a controlled, 3D surface morphology will be used to both improve bonding and, crucially, enable control of the TBC microstructure. In particular providing a much higher segmentation crack density. Most failures in TBC systems occur at the interface between the topcoat and the bond coat. Interfacial adhesion will be improved by the introduction of nano-crystalline inter-layers. Finally, new processes for the deposition of the TBC will be studied. These include; thin film - LPPS, plasma enhanced CVD, nano-p hase suspension PS and high speed PVD. Unlike EB-PVD, they will enable advanced TBC materials such as alumina based to be used. The project aims to provide significant improvements to TBC systems using a number of innovative steps. It is expected that th is work will not only extend the life of conventional TBC's but also provide the breakthrough necessary to achieve 'next generation' TBC systems.Maintaining a lead in gas turbine technology is strategically important for Europe. The participation of all the key European companies in this sector not only underscores the importance of this project but also ensures that the results will have the widest possible impact and benefit.
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