Effect of Composition on the Lifetime of Thermal Barrier Coatings

In this study, more advanced materials for ceramic top coat, bond coat and super alloy substrates have been studied and their effect on the lifetime of TBC systems has been investigated. The aim is to study the failure mechanisms for different TBC systems in detail with the purpose of increasing the high temperature capability of the TBC systems and to improve their lifetime. The material tested for ceramic top coat application is Gadolinium Zirconate which is well known for it's higher thermal stability, lower thermal conductivity and better resistance to CMAS and volcanic ash attack. This material has been deposited on various bond coats and super alloy substrates and the furnace cyclic testing has been done. The lifetime and microstructural results are then compared with the standard 7YSZ based systems with the same bond coat and super alloy substrates. All the depositions have been carried out by Electron beam Physical Vapor Deposition (EBPVD) technique. This book includes intensive study on lifetime results, phase transformations, chemical reactions, diffusion of elements and sintering effects which take place in the TBC systems due to thermal cycling at high temperature.