Coating and surface technologies for turbine airfoils

Abstract

The development of single crystal superalloys over the past 20 years has allowed the turbine inlet temperatures of aircraft engines to increase significantly. With further advances in superalloy temperature capability becoming more difficult, coatings and other surface technologies are becoming more important. Various approaches to improving the coating system, including both the bond coat and the thermal barrier coating are discussed. It is shown that significant improvements can be made in both components of the coating system, allowing for higher operating temperatures. While the airfoil coating system is being improved, the airfoil tips and areas below the platform of the blade must also be addressed as well. A new, high temperature turbine blade tip alloy is introduced and the application of coatings to non-flowpath surfaces are also discussed. Material improvements in the entire turbine airfoil material system will continue to allow turbine inlet temperatures to increase.