Endurance of NiA1 coatings by controlling thermal spray processing variables

A method for applying substantially stoichiometric NiAl to the surface of a superalloy substrate. These coatings are applied to substrates subjected to high temperatures and thermal cycling by providing a powder of the substantially stoichiometric material with the desired minor additions of rare earth elements, Cr or Zr. The coatings are applied by a thermal spray process utilizing hydrogen as a fuel while generating a highly reducing flame. The thermal spray method melts the powder and directs it onto the surface of the turbine component that is to be coated. The powder size is carefully controlled to prevent oxidation of the powder while providing a controlled surface finish. The surface roughness of the bond coat is further mechanically worked to a predetermined surface finish prior to application of the ceramic thermal barrier layer by a PVD method. Thermal barrier systems applied using these carefully controlled predetermined parameters provide outstanding resistance to TBC spallation under conditions of high cyclic stresses.