Coated superalloy gas turbine components

Abstract From the Canadian patent

Low temperature regime hot corrosion of superalloy components in gas turbines is reduced by the application thereover of cobalt - chromium alloys the, chromium content of such coatings (final composition) being in the 37.5 - 50 weight percent range. To the extent practicable, aluminum content of these coatings is kept to a minimum. In any event, during the annealing step some small amount at least of aluminum migrates from the superalloy into the coating. At completion of the annealing operation, the aluminum content at the exterior surface of the final coating, however is to be, less than the concentration of aluminum that will form a continuous film of aluminum oxide.