Modeling of Thermally Grown Oxide Layer Growth as a Moving Boundary Problem Available to Purchase

Thermal efficiency of energy conversion systems such as gas turbines can be increased greatly with an increase in the turbine inlet temperature of combustion gases. However, this necessitates the use of efficient cooling techniques in addition to thermal barrier coatings (TBCs) to help significantly improve the life expectancy of gas turbine blades. The effect of TBC use is the formation of oxides, particularly alumina, at the interface of the ceramic top coat and bond coat material during in-service application. This effect is well known to cause failure of TBCs exposed to extreme high temperature environments. The objective of this paper is to present a micro-scale finite difference thermal model for the TBC-Substrate system that considers growth of the TGO layer and predicts in-situ thermal gradients. The governing equation is the transient heat diffusion equation discretized over a 1-D domain using mean value finite volume method with grid adaptation for zones involving depletion of bond coat (BC) material and TGO growth; hence, necessitating a moving interfacial boundary problem. The resulting algebraic equations are simultaneously solved in MATLAB to produce temperature distributions and BC/TGO interfacial locations. The model has utility in studying the evolution of residual stresses and hence prediction of TBC durability and failure.