Experimental investigation of residual thermal stress in thermal barrier coating (TBC)

Residual thermal stress, which has a strong effect on the coating performance, is generated during the fabrication of TBC. In this paper, the residual thermal stress in TBC (92%ZrO₂-8%Y₂O₃) with two different thicknesses (0.38 mm and 0.90 mm) is analyzed with a bi-material model. TBC specimens were sprayed by an Air Plasma Spray (APS). In addition, a chemical material removal method was used to obtain TBC specimens after it cooling down to the room temperature. Before and after the coating removed from the substrate, the deformation of the TBC was measured. Then the bi-material model was used to calculate the residual thermal stress in the TBC. The experiment result shows that, the residual thermal stress in thin TBC is smaller than that in thick TBC (the average residual thermal stress in thin and thick specimens are 145.5 MPa and 225.13 MPa respectively). The micro-structures in thin and thick TBC are also observed and discussed.