Characterization of Failure Mechanisms of Duplex and Graded Thermal Barrier Coatings Exposed to Thermal Shock Test

摘要

The beginning of failure of a (ZrO_2-7%Y_2O_3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex and graded coating systems on Inconel 617 and IN738LC in burner rig tests has been characterized. The test conditions are 40 s heating up to 750℃ substrate temperature followed by 80 s air cooling. Failure is considered at the appearance of the first bright spot during heating period. Stresses due to thermal expansion mismatch strains on cooling are the probable cause of life-limiting in this conditions of testing.