Patent ID: 8021491

Claim:
A method of removing an aluminum-containing overlay coating from a substrate of a gas turbine component, the overlay coating having an aluminum content of less than 12% by weight and being highly resistant to selective stripping, the method comprising: removing the component from a gas turbine after operation of the gas turbine and after growth of a protective alumina scale on an exposed outer surface of the overlay coating; diffusing aluminum into the overlay coating to form an aluminum-infused overlay coating having an increased aluminum level in at least an outer surface thereof, the increased aluminum level being sufficient to render the aluminum-infused overlay coating removable by selective stripping; and then contacting the outer surface of the aluminum-infused overlay coating With an aqueous composition to remove the aluminum-infused overlay coating from the substrate, the aqueous composition including at least one of an acid having the formula HxAF6, and precursors to said acid, A being selected from the group consisting of Si, Ge, Ti, Zr, Al, and Ga, and x being 1 to 6.