Advanced Coatings on Superalloy Blades and Vanes for Hot Corrosion and Oxidation Resistance

The need for surface protection of nickel base alloys to prevent hot corrosion and/or sulfidation is discussed. Results of controlled engine test cycling and the rig testing of turbine blades are discussed to establish laboratory test correlation. The relative corrosion resistance of a number of commercial alloys is shown, and the response of these alloys to corrosion resistance with protective coating is covered in relation to their limitation in erosion/oxidation deterioration. Finally, some technology results and general methodology applied to electrophoretic processing for applying coatings of aluminum and combinations with chromium are described. The processing advantages and disadvantages of this coating process and general results are compared with present production.