Aluminide coating for superalloys
AssigneeUnited Technologies Corporation
InventorsWalter E. Olson, Dinesh K. Gupta
Life of this patent
Estimating the term…
Abstract
A protective coating system for superalloys is described. The coating is an active element enriched aluminide, and can be formed by aluminizing an overlay coated superalloy, wherein during the aluminizing process, aluminum diffuses completely through the overlay coating and into the substrate. The coating system exhibits desirable oxidation resistance and resistance to thermal fatigue cracking, due to the presence of oxygen active elements in the overlay.
Claims17
An article having resistance to oxidation and thermal mechanical fatigue comprising a substrate selected from the group consisting of nickel and cobalt base superalloys, and a coating 0.001-0.005 inches thick diffused with the substrate, wherein the coating has an outer zone and a diffusion zone inward thereof, the outer zone consisting essentially of, by weight percent, 21-35 Al, 0.1-5 Y, 0.1-7 Si, 0.1-2 Hf, 5-30 Cr, 10-40 Co, and the balance nickel, and the diffusion zone having a lesser concentration of aluminum than the outer zone.
A process for producing a coated nickel or cobalt base superalloy article having resistance to oxidation and thermal fatigue, comprising the steps of:
- (a) applying a 0.0005-0.003 inch thick overlay coating to the superalloy surface, wherein said overlay coating contains yttrium, silicon and hafnium;
- and
- (b) diffusing aluminum through the overlay coating and into the superalloy substrate so as to form a coating characterized by an outer coating zone containing about 21-35 weight percent aluminum and a diffusion zone between the outer zone and the substrate, wherein the diffusion zone has a lesser concentration of aluminum than the outer zone and the combined thickness of the outer coating zone and the diffusion zone is about 0.001-0.005 inches.
A process for producing a coated nickel or cobalt base superalloy article having resistance to oxidation and thermal fatigue, comprising the steps of:
- (a) applying a 0.0005-0.003 inch thick overlay coating to the superalloy surface, wherein said overlay coating contains at least two oxygen active elements in a combined amount between about 0.5 and 9 weight percent;
- and
- (b) diffusing aluminum through the overlay coating and into the superalloy substrate so as to form a coating characterized by an outer coating zone containing about 21-35 weight percent aluminum and a diffusion zone between the outer zone and the substrate, wherein the diffusion zone has a lesser concentration of aluminum than the outer zone and the combined thickness of the outer coating zone and the diffusion zone is about 0.001-0.005 inches.
Dependencies are inferred from the claim text.