Method for producing an abradable seal
AssigneeUnited Technologies Corporation
InventorsGerard A. Sileo, John W. Appleby, Stephen T. Narsavage, Francis X. Alent, Charles G. Davis
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Abstract
A gas turbine abradable seal is prepared by plasma spraying an oxidation resistant metallic material and boron nitride. The resultant structure comprises a metallic matrix encompassing a lubricating amount of boron nitride, with porosity of less than about 15 percent and a fabricated surface roughness of less than about 600 microinches. The reduced surface roughness and substantially reduced permeability of this seal provide substantially enhanced engine efficiency, and improved durability.
Claims13
A method for producing a substantially gas impermeable abradable seal having a surface roughness of less than about 600 microinches and minimal interconnected pores, said method comprising:
- a. Providing a metallic substrate;
- b. Plasma spraying onto said substrate a low porosity bond coat layer consisting essentially of a nickel based superalloy having a density greater than 90 percent theoretical, and having an oxidation resistance greater than that of nichrome at 1200.degree. F., wherein said bond coat layer does not contain boron nitride;
- and
- c. Forming a substantially gas impermeable abradable seal having a surface roughness of less than about 600 microinches and minimal interconnected pores by plasma spraying over said bond coat layer an abradable layer comprising 50 to 65 volume percent oxidation resistant nickel based superalloy, 20 to 45 volume percent hexagonal boron nitride, and from about 5 to about 15 volume percent porosity.
A method for producing a substantially gas impermeable abradable seal having a surface roughness of less than about 600 microinches and minimal interconnected pores, said method comprising:
- a. Providing a metallic substrate;
- b. Plasma spraying onto said substrate a bond coat layer containing no boron nitride, said bond coat layer comprising, by weight, 5-26 percent Cr, 3-13.2 percent Al, 0.1-1.5 percent Hf, 0.001-0.80 percent Y, 0-5.0 percent Ti, 0-24 percent Co, 0-15 percent W, 0-4 percent Mo, 0-12 percent Ta, 0-0.2 percent Zr, 0-0.2 percent B, 0-0.25 percent C, 0-0.60 percent Si, 0-7.0 percent Re, 0-5.0 percent Cb, 0-0.2 percent iron, 0-0.1 percent copper, 0-0.05 percent of each of phosphorus, sulfur, lead, bismuth, and manganese, the balance essentially Ni;
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- c. Forming a substantially gas impermeable abradable seal having a surface roughness of less than about 600 microinches and minimal interconnected pores by applying to said bond coat layer, by multiple port injection plasma spraying, an abradable layer comprising 50-65 volume percent oxidation resistant superalloy, 20 to 45 volume percent hexagonal boron nitride, and from about 5 to about 15 volume percent porosity, wherein said superalloy comprises the same composition as said bond coat layer.
Dependencies are inferred from the claim text.