Collaborative Research on Adhesion Strength of Thermal Barrier Coatings in JSMS

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This paper introduces the brief summary of the recent collaboration test results on thermal barrier coatings (TBCs) in the JSMS Subcommittee, which covers the measurements of elastic modulus, tensile strength, residual stress and thermal conductivity of the TBC specimens. Here, the round-robin TBC specimens consisting of 8% yttria stabilized zirconia, CoNiCrAlY alloy bond coat and Ni-base superalloy were prepared by plasma spraying method. The isothermal exposure and the thermal cycles were applied to the TBC specimens by several conditions at high temperatures, to measure both the residual stress and the remaining adhesion strength of the ceramic top, as well as to characterize the thermally grown oxide at the top coat/bond coat interface. The round-robin test results clearly demonstrated that the adhesion strength was significantly changed by the application of thermal cycles and the isothermal exposure. Of particular important results was found in the remaining adhesion strength that were strongly dependent on the testing method to give the thermal cycles.