The effect of preoxidation atmosphere on oxidation behavior and thermal cycle life of thermal barrier coatings

The effects of oxygen partial pressure (pO2) of the preoxidation atmosphere on the growth of thermally grown oxide (TGO) and thermal cycle life of plasma-sprayed thermal barrier coatings (TBCs) were investigated. The pO2 of the preoxidation atmosphere was controlled by using a solid-state electrochemical oxygen pump system. The purity and microstructure of continuous Al2O3 layer formed on the bond coat during preoxidation at 1050 °C were highly influenced by the pO2 of the atmosphere. The specimen preoxidized at 1050 °C under a pO2 of 10−14 to 10−15 atm, which is around the dissolution pressure of (Co, Ni)(Al, Cr)2O4 spinel, showed the lowest growth rate of TGO and the longest thermal cycle life.