Computational Modeling of 2D Thermal Barrier Coating Microstructures

Thermal barrier coatings are used to reduce base metal temperature and can be found on many engine components such as turbine blades and exhausts. The presented work is part of a broader effort which is focused on maintaining mechanical properties while improving thermal properties of candidate thermal barrier coating materials. Specifically this effort is investigating new and novel processing techniques to improve thermal properties while maintaining sufficient mechanical properties so that coatings do not fail due to the loads inherent to normal operation of the component. Processing methods have been investigated that create new microstructures by the inclusion of spherical, micron size pores to reflect radiation (i.e. heat) at high temperatures providing additional thermal protection while maintaining strength. This paper computationally examines the size, distribution, and structure of pores that develop during bulk processing of a model material, yttria-stabilized zirconia (YSZ) to aid in the formulation of an optimized process. Heat transfer and stress-displacement analyses are performed to determine effective bulk material properties. Two-dimensional microstructures are the first step towards understanding the impact of pores, voids and microcracks on thermal and mechanical characteristics. In this work two-dimensional microstructures are computer generated to determine the influence on variations in pore number, size and relative percent of pores and cracks. Comparisons are made to experimental measurements when appropriate.