TBC Characterization Using Hybrid Sensors with Multivariate Inversion Methods

This proposed effort will develop a TBC characterization methodology based on inductive (MWM), capacitive (IDED), and/or hybrid sensors using multivariate inversion algorithms. Phase I will include the development of a flexible IDED, the study of hybrid MWM/IDED multivariate measurement techniques and work toward the development of IDED or hybrid segmented-field arrays. These arrays will provide independent measurement of up to five unknown properties of the coating system, e.g., ceramic coating thickness and porosity, bondcoat thickness and porosity, and substrate thermal aging. This Phase I program also contains important preparatory steps that will support application of the hybrid sensors for TBC life cycle monitoring by building understanding of the relationships between coating quality, coating degradation mechanisms, and coating electromagnetic properties. This new NDI capability for TBCs would be applicable to all stages of the turbine engine life cycle, by providing the coating developer with a reliable coating screening method, the coating manufacturer with enhanced quality control, and the turbine engine operator with a means of ensuring coating structural integrity, implementing retirement/refurbishment for cause, and estimating life expectancy. This will result in cost savings for the entire engine life cycle.