Influence of Topcoat-Bondcoat Interface Roughness on Stresses and Lifetime in Thermal Barrier Coatings

In previous work, it was observed that atmospheric plasma sprayed bond coats perform better than their HVOF counterparts, which is contrary to current literature data. The objective of this work is to understand the observed difference with the aid of finite-element modeling. Different thermally grown oxide layer thicknesses and surface topographies are evaluated and the modeling results are compared with current theories based on simplified sinusoidal profiles. It is shown that modeling can be used as an effective tool to understand the stress behavior in TBCs with different roughness profiles.