ICME Computational Framework for Ceramic APS Coatings

Abstract

Abstract Integrated Computational Material Engineering (ICME) framework for Air Plasma Spray (APS) process for ceramic coatings is developed for optimizing multifunctional coatings and APS process for Thermal Barrier Coating (TBC) system. ICME simulations of APS process for TBC, the burner rig test and furnace test of TBC have been performed along with the test validation of ICME predictions for Yttria-stabilized-zirconia (YSZ) TBC with APS 8YSZ top coating with / NiCoCrAlY bond over Waspaloy substrate. ICME predictions for residual deflection of TBC due to thermal loads after APS process, burner rig test and furnace test are in close agreement with the test results. Both test and ICME predictions show the as-manufactured TBC specimens exhibit bending after APS process and bending after Burner Rig and Furnace testing. Finite element model for TBC specimens shows bending induced by APS process, its thermal gradients and residual thermal stress. Microscale thermal models for APS process, burner rig test and furnace test have been used to predict thermal processes, porosity and stresses. Rumpling analysis of TBC predicts rumpling amplitude due to thermal stresses and thermal oxidation growth (TGO) in TBC, thickness of TGO, bond stress during rumpling and stresses in TGO layer. Predictions for the thickness of TGO compares well with experimental data. Progressive damage analysis revealed that failure is due to tension and out of plane shear, delamination growth due to oxidation penetrating YSZ TBC from the bond.