Evaluation of delamination on thermal barrier coatings by stress measurement and addition of strengthening mechanism

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Thermal barrier coating systems (TBCs) have been widely used to increase the operating temperature of hot section components in gas turbines blades and vanes. TBCs usually consists of outer oxide ceramics top coat (TC) layer and inner intermetallic bond coat (BC) layer in order to protect the Ni-base superalloy from high temperature and oxidation. During the service, TGO forms and this formation increases the residual stress of the coating. Delamination of TGO/BC interface occurs because of the increasing residual stress and finally TC layer spall off from the TBCs. In this research, local stress components were evaluated by Wilkinson method where the stresses were decided by the distortion of the EBSD pattern. Further, high toughened TBCs were formed by using the stress dissipation of the BC layer due to the low yield stress by heat treatment.