Stability Loss and Delamination of a Thermal Barrier Coating from the Substrate under Heat Loads

The paper proposes a simple two-layer model to assess the behavior of a heat-loaded thermal barrier coating–substrate system with neglect of thermally grown oxide and bond coat. The model includes solutions of boundary value problems of thermal conduction, thermoelasticity, stability, and stress-strain state after stability loss, and it also provides for coating delamination from the substrate after stability loss. It is shown that when the coating–substrate system is exposed to intense heat, the coating experiences compressive stresses which can cause a loss of its stability. When the coating losses its stability on the elastic substrate, chess-board extrusion and intrusion regions with respective tensile and compressive zones arise in the system. At a critical stress intensity, the system losses its continuity at the coating–substrate interface, and the coating delaminates from the substrate in tensile zones. The zones of delamination at the coating–substrate interface are arranged periodically.