Tensile damage evolution behavior in plasma-sprayed thermal barrier coating system

Cracking and fracture behavior in a plasma-sprayed thermal barrier coating system were evaluated using a sandwiched specimen under uni-axial tensile stress combined with an in situ microscope observation. It was found that initial crack initiation and transverse crack propagation occurred in the top coat layer. The number of transverse cracks increased rapidly and then saturated with an increase in tensile strain. After the saturation of the multiple cracks, the cracks passed through the interface between the top coat and bond coat, and propagated in the bond coat. Finally, decohesion occurred at the bond coat/substrate interface when the transverse cracks reached the interface. A model was proposed to describe the fracture processes.