2420 Development of High-Sensitive Non-Destructive Evaluation Technique of Degraded Thermal Barrier Coatings by Using Microwave

概要

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Thermal barrier coatings (TBCs) have been widely used in gas turbine engines in order to protect the substrate metal alloy against high temperature and to enhance turbine efficiency. After service at high temperature, delamination or micro-cracks will initiate in TBC, leading to TBC separation from substrate and ultimately in unexpected gas turbine destruction. TBC failure is primarily attributed to the. growth of TGO and partly to TBC degradation. Currently, there are no reliable nondestructive techniques available to monitor TBC integrity over lifetime of the coating. Thus, to detect TBC and TGO thicknesses, a microwave nondestructive technique that utilizes a rectangular waveguide was developed. The phase of the reflection coefficient at the interface of TBC and waveguide varies for different TGO and TBC thicknesses. Therefore, measuring the phase of the reflection coefficient enables us to accurately calculate TGO and TBC thicknesses. Finally, a theoretical analysis was used to evaluate the reliability of the experimental results.
社団法人日本機械学会の論文
2007-09-07