Use of the finite element technique to analyze thermal stress in coating under thermal loading conditions

Thermal stress due to the mismatch between the coating and substrate is an important factor to ensure the reliability of the coating for its various structural and function applications at high temperature. In the present work, the thermal stress distributions through the thickness of TiO₂ coating-substrate systems, as well as the effect of the mismatch between the coating and substrate, and the intermediate composite layer (which is a graded composite made of the SiO₂ and TiO₂ materials) on the thermal stress are evaluated by Finite Element Method (FEM). The results show that TiO₂ coating on Si substrate exhibits high thermal stress at high temperature compared to the sapphire//TiO₂ system and TiO₂-SiO₂ material as the intermediate composite layer is effective for decreasing and controlling the stress distribution.