The durability of thermal barrier coatings is governed by a sequence of cra
ck nucleation, propagation and coalescence events that accumulate prior to
final failure by large scale buckling and spalling. Because of differing ma
nufacturing approaches and operating scenarios, several specific mechanisms
are involved. These mechanisms have begun to be understood. This article r
eviews this understanding and presents relationships between the durability
, the governing material properties and the salient morphological features.
The failure is ultimately connected to the large residual compression in t
he thermally grown oxide through its roles in amplifying imperfections near
the interface. This amplification induces an energy release rate at cracks
emanating from the imperfections that eventually buckle and spall the TBC.
(C) 2001 Elsevier Science Ltd. All rights reserved.