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.
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