Delamination buckling and spalling of plasma-sprayed thermal barrier coatings

Monitoring Delamination of Plasma-Sprayed Thermal Barrier Coatings by Reflectance-Enhanced Luminescence

Highly scattering plasma-sprayed thermal barrier coatings (TBCs) present a challenge for optical diagnostic methods to monitor TBC delamination because scattering attenuates light transmitted through the TBC and usually degrades contrast between attached and delaminated regions of the TBC. This paper presents a new approach where reflectance-enhanced luminescence from a luminescent sublayer inc...

Failure analysis of suspension plasma sprayed thermal barrier coatings

Simulation of stresses and delamination in a plasma-sprayed thermal barrier system upon thermal cycling

A thermal barrier system with plasma-sprayed thermal barrier coating (TBC) has been analyzed subject to thermal cycling. The thermally grown oxide (TGO) is allowed to grow at the peak temperature in the cycle, with both thickening and lateral components of the growth strain. The stresses in the TGO are also allowed to relax at high temperature when they attain a critical level. The bond coat is...

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 ...

Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

Suspension plasma spraying (SPS) has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD) coatings. Additionally, SPS coa...