Insight into the Mechanical Behaviour of Cooling Rate-Dependent Blistering Failures in Alumina Films

The blistering and spallation failures in alumina films formed on Kanthal substrates have gained significant attention due to the importance of high-temperature materials in various industrial applications. This work aims to investigate the underlying mechanism for the circular interfacial separations that develop spontaneously under the constant compressive residual stresses at room temperature. This study employed analytical mechanical models and finite element simulations that are based on the conventional buckling theories. In detail, the thermal mismatch stress, alumina growth stress and creep of the substrate are included and the linear fracture locus criterion with the fracture toughnesses in mode I and II are used. The finite element model is established and the results reveal the initial separation is essential for blistering triggered by buckling. However, for the originally intact interface, the pockets of energy concentration theories are suggested to use. The present work highlights the difficulties for the blistering and spallation failures in thin films, having significant implications for the design and performance of high-temperature materials.