Claims
- 1. A metallic article comprising:
- a substrate of a superalloy based on an element selected from the group consisting of Fe, Co and Ni, and
- a graded coating diffused with said substrate to increase the hot corrosion resistance of the substrate, the graded coating consisting essentially of:
- (i) an inner coating portion adjacent to and diffused with the substrate, and consisting essentially of, by weight, 8-30% Al, 10-50% Cr, up to 10% Hf, up to 30% of elements selected from the group consisting of Pt, Rh and Pd, up to 3% Y, with the balance at least one element selected from the group consisting of Fe, Co and Ni, and elements diffused from the substrate and the outer coating portion and
- (ii) an outer coating portion adjacent to and diffused with the inner coating portion, and consisting essentially of 5-50 weight percent of elements selected from the group consisting of Hf, Pt, Rh and Pd, with the balance elements diffused from the inner coating portion.
- 2. The article of claim 1 in which the outer coating portion includes 2-5% Hf and 5-40% Pt.
- 3. The article of claim 2 in which the outer coating portion includes 20-40% Pt.
- 4. The article of claim 1 in which the inner coating portion consists essentially of, by weight, 8-20% Al, 10-40% Cr, up to 5% Hf, up to 20% of at least one element selected from the group consisting of Pt, Rh and Pd, up to 2% Y with the balance at least one element selected from the group consisting of Fe, Co and Ni.
- 5. The article of claim 4 in which the Al is 9-16% and the Cr is 20-30%.
Government Interests
The invention herein described was made in the course of or under a contract or subcontract thereunder (or grant) with the Department of the Navy.
US Referenced Citations (7)