Micromechanical Simulation of Thermal Cyclic Behavior of ZrO2/Ti Functionally Graded Thermal Barrier Coatings

Abstract

This study numerically investigates cyclic thermal shock behavior of ZrO2/Ti functionally graded thermal barrier coatings (FG TBCs) based on a nonlinear mean-field micromechanical approach, which takes into account the time-independent and dependent inelastic deformation, such as plasticity of metals, creep of metals and ceramics, and diffusional mass flow at the ceramic/metal interface. The fabrication processes for the FG TBCs have been also considered in the simulation. The effect of creep and compositional gradation patterns on micro-stress states in the FG TBCs during thermal cycling has been examined in terms of the amplitudes, ratios, maximum and mean values of thermal stresses. The compositional gradation patterns highly affect thermal stress states in case of high creep rates of ZrO2. In comparison with experimental data, maximum thermal stresses, amplitudes and ratios of thermal stresses can be effective parameters for design of such FG TBCs subject to cyclic thermal shock loadings.

Special Issue: Tribological Coatings—Properties, Mechanisms, and Applications in Surface Engineering

“…Both types of coatings are applied to hard substrates or substrates with a hardened surface layer [1,2,4,6,15]. In most applications of tribological coatings, such as thermal barriers for gas turbines [16], hard coatings for cutting tools [17] or hard and tough coatings for molds for casting metals [18] or polymers [19], they serve as multifunctional coatings with a special combination of properties. Due to their microstructure and application in the most difficult conditions, special groups of tribological coatings include nanostructured and nanocomposite coatings [20][21][22] and biomedical coatings [23].…”