Damage Evaluation of Thermal Barrier Coatings Subjected to a High-Velocity Impingement of a Solid Sphere under Room and High Temperature Conditions

抄録

Thermal barrier coatings (TBCs) applied to turbine blades in jet engines or gas turbines are at risk of high-velocity impingement from different foreign objects, which can cause severe damage from delamination of the TBC. In this study, a high-velocity impingement test system is developed under high-temperature conditions to understand the delamination mechanism of TBCs under actual operation conditions. In this system, a spherical impactor with a diameter of 1–8 mm can be impinged onto a TBC specimen at different temperatures up to 900°C. High-velocity impingement tests were conducted on atmospheric plasma-sprayed TBC specimens with 8 mass% yttria-stabilized zirconia topcoat (TC) under room temperature (RT) and 900°C conditions. The results indicate that a hemispherical indentation was formed at 900°C, which indicates plastic deformation of the TC, unlike the brittle deformation observed at RT. In addition, vertical and interfacial cracks formed under both RT and 900°C conditions. Cross-sectional observation revealed that the formation process of the interfacial crack at 900°C was different from that at RT. In particular, the interfacial crack tended to become significantly longer at more than 170 m/s at 900°C.

 

This Paper was Originally Published in Japanese in the J. Japan Thermal Spray Society 58(1) (2021) 4–10. The abstract and captions of Figs. 1–8, 10 and 11 were slightly modified from the original paper.