Development of Plasma-Sprayed Thermal Barrier Coatings with Low Thermal Conductivity and High Oxidation Resistance (Review)

The continuous increase of the turbine inlet temperature in gas turbines necessitates new thermal barrier coatings (TBCs) with enhanced temperature capability and longer lifetime. This paper reviews our recent challenges to develop new plasma-sprayed TBC systems for the next generation of land-based gas turbine engines. It is shown that the addition of small amounts of La2O3 is effective in reducing the thermal conductivity of Y2O3-stabilized ZrO2 plasma-sprayed top coats. It is also revealed that precise control of the oxygen partial pressure of the pre-oxidation atmosphere leads to an improvement of the oxidation resistance of MCrAlY bond coats. The newly-developed TBCs show much longer thermal cycle life than that of conventional coatings.