Fabrication of superalloy articles having hafnium- or zirconium-enriched protective layer
AssigneeGeneral Electric Company
InventorsRamgopal Darolia, William S. Walston
Life of this patent
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Abstract
A superalloy article has a protective layer thereon, either in the form of an environmental coating or a the bond coat for a thermal barrier coating system. The protective layer has a high content of hafnium and/or zirconium to improve the adherence and properties of the protective layer. To introduce the hafnium and/or zirconium into the protective layer, the nickel-base alloy substrate, to which the protective layer is applied, is prepared with an initially elevated content of the hafnium and/or zirconium. A conventional bond coat is applied to the substrate. In an interdiffusion treatment performed during coating and/or subsequently, hafnium and/or zirconium diffuses from the substrate into the bond coat.
Claims18
A method for preparing a single-crystal superalloy article having a protective layer thereon, comprising the steps of
- selecting a nickel-base superalloy composition;
- preparing a modified version of said nickel-base superalloy composition, wherein the modified version of said nickel-base superalloy composition has an excess of a protective-layer modifying element over that of the nickel-base superalloy composition, the protective-layer modifying element being selected from the group consisting of
- from about 0.2 to about 2.0 percent by weight hafnium, and
- from about 0.1 to about 0.5 percent by weight zirconium, and combinations thereof;
- processing the modified version of said nickel-base superalloy composition into a substrate having the shape of the article and being substantially a single crystal;
- applying a protective layer to a surface of the substrate, the as-applied protective layer having a lower concentration of the protective-layer modifying element than the substrate;
- and
- interdiffusing the protective layer modifying element from the substrate into the applied protective layer.
A method for preparing a single-crystal superalloy article having a protective layer thereon, comprising the steps of
- selecting a nickel-base superalloy composition;
- preparing a modified version of said nickel-base superalloy composition, wherein the modified version of said nickel-base superalloy composition has an excess of a protective-layer modifying element over that of the nickel-base superalloy composition, the protective-layer modifying element being selected from the group consisting of
- from about 0.2 to about 2.0 percent by weight hafnium, and
- from about 0.1 to about 0.5 percent by weight zirconium, and combinations thereof;
- processing the modified version of said nickel-base superalloy composition into a substantially single-crystal substrate having the shape of an article selected from the group consisting of a turbine blade and a turbine vane;
- applying a protective layer to a surface of the substrate, the as-applied protective layer having a lower concentration of the protective-layer modifying element than the substrate;
- interdiffusing the protective layer modifying element from the substrate into the applied protective layer;
- and
- depositing a ceramic layer overlying the protective layer.
Dependencies are inferred from the claim text.