The effect of pre-oxidation atmosphere on the durability of EB-PVD thermal barrier coatings with CoNiCrAlY bond coats

The effects of pre-oxidation heat treatment on oxidation behavior and thermal cycle life of electron-beam physical deposited (EB-PVD) thermal barrier coatings (TBCs) with CoNiCrAlY bond coats were investigated as a function of the pO2 of the pre-oxidation atmosphere. The pO2 of the pre-oxidation atmosphere was controlled by using a solid-state electrochemical oxygen pump system. The purity and microstructure of the continuous Al2O3 layer formed on the bond coat during pre-oxidation at 1050 °C were highly influenced by the pO2 of the atmosphere. High purity α-Al2O3 with large grain size was formed on the bond coats under a pO2 of 10− 12–10− 9 Pa, which resulted in a lower growth rate of TGO and longer lifetime.