Damage progression in thermal barrier coating systems during thermal cycling: A nano-mechanical assessment

Abstract

Nanomechanical properties of thermal barrier coatings were measured by high-speed nanoindentation and pillar splitting During thermal cycling, delamination damage progresses slowly as long as the bond coat forms a dense, tough oxide scale The fracture toughness of the thermally grown oxide scale drops when its thickness exceeds a 5-m threshold Severe delamination damage starts from the embrittled thermally grown oxide and propagates across the zirconia top coat Such propagation is favoured by a simultaneous drop in top coat strength, due to accumulated microstructural alterations