Use of Indentation Fracture Tests to Investigate Toughness Loss Mechanisms in Thermal Barrier Coating Systems

摘要

Loss of adhesion is a major concern in thermal barrier coating (TBC) systems used to insulate gas turbine components. Fracture mechanics-based indentation tests have been developed to quantify interfacial fracture toughness loss in electron beam physical vapor deposition (EB-PVD) TBC systems. Through the integration of indentation fracture test methods and electron microscope visualization techniques, the degradation of interfacial fracture toughness can be tracked quantitatively with thermal exposure history. In the present paper, the tracking of toughness loss and identification of the mechanisms causing it are demonstrated for TBCs subjected to isothermal dry air and cyclic dry air thermal exposures at 1100°C. Although tests to date have been on EB-PVD TBCs, the methods presented may also be applicable to other TBC systems.