Interfacial Strength Evaluation Technique for Thermal Barrier Coated Components by Using Indentation Method

YasuhiroYamazaki, Shin-ichiro Kuga, Murugesan Jayaprakash
2011 Procedia Engineering  
Thermal barrier coatings (TBCs) have been essential technologies to improve the performance and efficiency of advanced gas turbines, which are in service at extremely high temperatures. Interfacial strength is one of the important properties in TBCs, and it has been often evaluated by tensile method, e.g. the ASTM standard; ASTM C633. However, the applicability of tensile method is limited, due to its size dependence. To overcome this problem, a new method has been proposed in the previous
more » ... to evaluate the interfacial strength using indentation method. In the present study, the interfacial strength of TBC which was subjected to thermal cycle fatigue has been investigated using the newly proposed indentation method. And also, the applicability of the proposed indentation method to evaluate the interfacial strength of retired TBC vane has been investigated. The results showed that; (1) Interfacial strength of the ceramic top-coat increased with the thermal cycles due to the sintering of ceramic topcoat. (2) TGO layer becomes thicker and micro cracks are initiated at the interface between the TGO layer and the bond-coat after thermal cycle fatigue. (3) The residual stresses in the ceramic top-coat and the TGO layer are varied with the thermal cycle fatigue. (4) Interfacial strength of a retired TBC vane was almost comparable to that of the as-sprayed TBC specimen because the thermal damage of the retired TBC vane was not severe.
doi:10.1016/j.proeng.2011.04.139 fatcat:a6i3e3tpezalfdrbjgqc5osjzq