Morphological evolution and failure of LZC/YSZ DCL TBCs by electron beam-physical vapor deposition

Abstract Low thermal conductivity thermal barrier coatings (TBCs) with double ceramic layers (DCL) structure are receiving tremendous attention for promising application in advanced gas turbine engine. It still remains a big challenge for the investigation of morphological evolution of TGO and failure model in new DCL coatings. Here we describe La 2 O 3 -ZrO 2 CeO 2 (LZC)/YSZ DCL TBCs prepared by electron beam-physical vapor deposition (EB-PVD). A composite of pyrochlore and fluorite is formed in LZC/YSZ coating. The microstructure of LZC/YSZ coating is composited of feathery nanostructure and intra-columnar pores. The LZC/YSZ DCL coating shows relativity low thermal conductivity and high thermal cycling lifetime. The growth behavior of TGO layer in LZC/YSZ coating is investigated in detail showing two distinct features (parabolic growth kinetics and straight growth kinetics). The evolution of residual stress has been experimentally measured and discussed by Raman spectroscopy. Based on the experimental data, the growth behavior of TGO layer, the evolution of residual stress and the element outward diffusion would be the primary factors for the failure of LZC/YSZ DCL TBCs.