Patent ID: 7163718
Filing Date: 2007-01-16
Classification: C23C,Y02T,Y10T

Abstract:
1. A process for forming diffusion aluminide coatings on an uncoated portion of a surface of a substrate, without interdiffusing a sufficient amount of aluminum into a coating layer to adversely affect the coating growth potential or mechanical properties of said coating layer, comprising the steps of: providing a metal substrate comprising an external surface and an internal passage therein defined by an internal surface, at least a portion of the external surface of the substrate being coated, but at least a portion of the internal surface being uncoated, with a coating layer selected from the group consisting of β-NiAl-base, MCrAlX, a line-of sight diffusion aluminide, a non-line-of-sight diffusion aluminide, a pack diffusion aluminide, and a slurry diffusion aluminide on said substrate, wherein the substrate is a gas turbine airfoil, and wherein the internal passage is a plurality of internal cooling passages which extend through an interior of the airfoil; cleaning the external surface of the substrate; subjecting the metal substrate to an aluminum vapor phase deposition process performed using a fluorine-containing activator selected from the group consisting of AlF cooling the substrate.