Effect of water vapor on the 1100 °C oxidation behavior of plasma-sprayed TBCs with HVOF NiCoCrAlX bond coatings

► 10% water vapor reduced 1100 °C lifetimes of APS TBCs on NiCoCrAlX bond coats. ► 50% water vapor did not further decrease TBC lifetimes at 1100 °C. ► TBCs with HVOF NiCoCrAlYHfSi bond coats had improved lifetimes over NiCoCrAlY. ► Additions of trace amounts of La and Y to SX superalloys did not improve TBC life. ► Longer thermal cycle duration substantially increased total time to TBC failure.