Patent ID: 7749569
Filing Date: 2010-07-06
Classification: C23C,Y02T

Abstract:
1. A method for providing corrosion and oxidation resistance to an under platform region of a gas turbine blade, the method comprising the steps of: a) providing a gas turbine blade comprising a superalloy selected from the group consisting of nickel-base superalloys, cobalt-base superalloys, iron-base superalloys, and combinations thereof, the blade further comprising an under platform region having an exterior surface; b) providing a slurry composition, wherein the slurry composition is substantially free of hexavalent chromium, and wherein the slurry composition comprises colloidal silica and aluminum-based powder; c) applying the slurry composition to a pre-selected portion of the exterior surface of the under platform region; d) subsequent to (c), heating the gas turbine blade under suitable diffusion conditions to form a silicon-modified aluminide coating on the pre-selected portion, wherein the cure conditions are operably selected to provide at least about 20% by weight aluminum and about 3% by weight silicon in the outer 25% of a coating thickness; and e) subsequent to (c), pre-curing the slurry composition under ambient or elevated temperature conditions to form a pre-cured coating and inspecting the pre-cured coating for at least one surface defect selected from cracking, flaking, and excess buildup prior to (d).