Wet chemical process for removing an abrasive alumina seal tooth coating

Abstract

A wet chemical process for removing an abrasive oxide coating from the surface of a rotating turbine engine component, such as a tooth that forms a rotating air seal with a complementary sealing member. The process generally entails subjecting the coating to a caustic solution at an elevated pressure. The caustic solution is preferably a mixture of water and a base, such as sodium or potassium hydroxide, with the addition of an organic compound being a preferred constituent in a sufficient amount as a solvent media for the caustic solution. A suitable caustic solution contains the base and water at a ratio of about one to one (1:1). If present, the organic compound may constitute about one to about ninety-eight weight percent of the solution. The process is preferably carried out in an autoclave charged with the caustic solution. Under an elevated pressure and preferably an elevated temperature, the caustic solution is capable of completely removing an alumina seal tooth coating without damaging an underlying bond coat or the tooth substrate.