Mechanisms governing the performance of thermal barrier coatings

Thermal barrier coatings (TBCs) are now used on hot section components in m ost commercial turbine engines. They are used to enhance the temperature di fferential between the gas and the underlying metal surfaces. They comprise several layers designed to simultaneously provide thermal and oxidation pr otection. They have microstructures which afford sufficient strain toleranc e that they remain attached despite severe thermomechanical cycling. Eventu ally, they spall. This happens because a thin, highly stressed, thermally g rown oxide (TGO) develops beneath the TBC. In this article, the specific me chanisms that contribute to failure are described, with the motivation that this understanding can be used to design TBCs having greater reliability a nd durability. (C) 1999 Published by Elsevier Science Ltd. All rights reser ved.