Delamination of multilayer thermal barrier coatings

Delamination of multilayer thermal barrier coatings

Multilayer thermal barrier coatings (TBCs) on superalloy substrates are comprised of an intermetallic bond coat, a thermally grown oxide (TGO) layer, and a porous zirconia top coat that provides thermal protection. The TGO attains a thickness of 1±10 lm prior to failure, while the bond coat and zirconia layer are each about 50±100 lm thick. The preferred method for manufacturing TBCs comprises ...

Reaction, transformation and delamination of samarium zirconate thermal barrier coatings

Delamination resistance of thermal barrier coatings containing embedded ductile layers

Micromechanical models are developed to explore the effect of embedded metal layers upon thermal cycling delamination failure of thermal barrier coatings (TBCs) driven by thickening of a thermally grown oxide (TGO). The effects of reductions in the steady-state (i.e. maximum) energy release rate (ERR) controlling debonding from large interface flaws and decreases in the thickening kinetics of T...

The Influence of Transient Thermal Gradients and Substrate Constraint on Delamination of Thermal Barrier Coatings

A systematic study of factors affecting the delamination energy release rate and mode mix of a thermal barrier coating attached to a substrate is presented accounting for the influence of thermal gradients combined with rapid hot surface cooling. Transient thermal gradients induce stress gradients through the coating and substrate, which produce overall bending if the substrate is not very thic...

On the delamination of thermal barrier coatings in a thermal gradient

Thermal barrier coating (TBC) systems are susceptible to delamination failures in the presence of a large thermal gradient. These failures, which occur within the TBC layer, are very different in character from those associated with the thermally grown oxide. Three possible causes of internal delamination are analyzed. In all cases, the thermomechanical properties of the TBC are allowed to vary...