Nondestructive Evaluation of Surface Treatments Including Thermal Barrier Coating Damage and Effectiveness

Ceramic thermal barrier coatings (TBC) and surface treatments are being developed for advanced turbine engine applications to provide critical insulation that results in lower component temperatures and extended fatigue life. This translates into improved reliability and efficiency with reduced life cycle costs. However, the durability of these coating systems remains a crucial issue at the higher operating temperatures and extended exposure times associated with current and next generation turbine engine designs. Standard inspection techniques are unable to detect pending TBC failure or other surface treatment failures until they have already occurred and with possibly, catastrophic effects. Distributed Source Positron Annihilation technology is a portable, near-surface inspection tool that has demonstrated the capability to quantify microstructural changes in surface treatments and TBCs.