Study on Electromotive Force Generated in Thermal Barrier Coatings at High-Temperature

Abstract

The purpose of this study is to propose the principle for detecting the damage of TBC deposited onto the gas turbine blade based upon the electromotive force generated between TBC surface and substrate at a high temperature. The electromotive force of TBC can be easily monitored at an elevated temperature. It was found that the exposure temperature generating the electromotive force was approximately 800K, which corresponds to ductile-brittle-transition temperature of the bond coating materials CoNiCrAlY in TBC system. Thus, there is a possibility to distinguish the damage patterns of the crack as piercing to the substrate and the crack as leading to delamination of top coat by detecting the electromotive force. As a future work, it is necessary to develop a high reliable technology to connect a conductor on the actual gas turbine blade surface to detect the electromotive force and relate between the generated electromotive force and TBC delamination life.Key words: Gas turbine blade, Thermal barrier coating, Damage detection, Delamination, Cracking, Electromotive force, High-temperature exposure, High-temperature tensile test