Modeling of the temperature field in a porous thermal barrier coating

Abstract

Abstract Thermal barrier coatings (TBCs) are advanced materials systems with low thermal conductivity. One of the reasons for the low thermal conductivity in TBCs is that they contain porous structures created by a network of micro-voids. In the present investigation, experimental and analytical studies of heat transfer in TBCs having different levels of porosity were performed. The ceramic coatings were analyzed using scanning electron microscopy to calculate the level of porosity and micro-pore size distribution. A two-dimensional FE model was then developed, where a stochastic method was used to define randomly distributed porous structures equivalent to porosities of 1%, 3%, and 5%. The results showed that the heat flux and temperature gradient were affected by the interactions between neighboring micro-pores and micro-pores/ceramic coatings, and that the effect of the micro-pores was limited to a small area (2–2.5 times the micro-pore radius). Based on the obtained results, a set of effective thermal conductivity equations are proposed which more clearly describe the heat transfer process in a porous TBC structure. Two different equivalent thermal resistance models were used to study the heat transfer process under low porosity ( 3%) conditions.