Transient and steady-state temperature distribution in thermal barrier coating systems under thermal shock and thermal time-harmonic loadings

In this study, the temperature fields in the thermal barrier coating systems (TBC) under various types of thermal loading, including steady and transient thermal loadings, is investigated. Due to the widely use of TBCs on gas turbine blades and the urgent need to increase the temperature of the combustion chamber, thermal barrier coatings are exposed to a variety of harsh thermal loadings, including thermal shock and periodic thermal loads. Therefore, the need to achieve the temperature distribution in different positions in the TBCs, especially in the protective coating is crucial. At first, due to the application of non-uniform temperature distribution on the boundary of the TBC layer, the steady-state temperature distribution inside the coating-substrate is obtained. Using the solution of steady-state temperature distribution as the initial condition, the transient temperature field inside the coating-substrate system is obtained. To investigate the thermal transient response of the TBC system, dual-phase lag (DPL) heat conduction equation is utilized. Fourier and Laplace integral transformations have been used to solve the temperature field equations. The effect of various types of thermal shocks and periodic thermal loading on the TBC is investigated. The results show that the steady-state and transient temperature fields strongly depend on the type of thermal shock, the thickness of the coating and the frequency of thermal loading.