Plasma sprayed abradable seals for gas turbine engines
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.
Claims21
A composite seal for gas turbine engines which comprises:
- a. a metallic substrate;
- b. an adherent bond coat on said substrate, said bond coat exhibiting low abradability and comprising an oxidation resistant superalloy;
- c. a homogeneous abradable layer plasma sprayed over said bond coat, said layer comprising 50 to 65 volume percent oxidation resistant superalloy, 20 to 45 volume percent hexagonal boron nitride, and less than about 25 volume percent porosity.
An abradable seal assembly for gas turbine engines, which seal comprises:
- a. a metallic substrate;
- b. an adherent bond coat on said substrate having a thickness of from 2 to 20 mils and consisting substantially of a plasma sprayed nickel based superalloy having an oxidation resistance exceeding that of nichrome at 1200.degree. F.;
- and
- c. a plasma sprayed abradable layer on said bond coat, said layer being from 10 to 200 mils in thickness, and comprising 50 to 65 volume percent nickel base super alloy having an oxidation resistance greater than that of nichrome and containing both yttrium and hafnium, a lubricating amount of hexagonal boron nitride, less than about 15 percent porosity, and a surface roughness, as fabricated, of less than about 600 microinches.
A composite seal for gas turbine engines which comprises:
- a. a metallic substrate;
- b. an adherent bond coat on said substrate, said bond coat having a thickness of from 2 to 20 mils, exhibiting low abradability and comprising an oxidation resistant superalloy;
- c. a homogeneous abradable layer plasma sprayed over said bond coat, said abradable layer exhibiting a wear index of less than 0.1, an erosion rate less than 0.020 cc/gram-of-erodant, and comprising a superalloy characterized by an oxidation resistance exceeding that of nichrome at 1200.degree. F. and containing both yttrium and hafnium wherein said abradable layer has a thickness of 10-200 mils and a porosity of from 5-15 volume percent.
An abradable seal assembly for gas turbine engines, which seal comprises:
- a. a metallic substrate;
- b. an adherent bond coat on said substrate having a thickness of from 2 to 20 mils and consisting substantially of a plasma sprayed nickel based superalloy having an oxidation resistance exceeding that of nichrome at 1200.degree. F.;
- and
- c. a plasma sprayed abradable layer on said bond coat, said layer being from 10 to 200 mils in thickness, and comprising 50 to 65 volume percent nickel base super alloy having an oxidation resistance greater than that of nichrome and containing both yttrium and hafnium, from 20 to 45 volume percent hexagonal boron nitride, less than 15 volume percent porosity, a surface roughness, as fabricated, of less than about 600 microinches, a permeability of less than about 20 percent, and a bulk density greater than 3.6 grams/cc.
An abradable seal assembly for gas turbine engines, said seal characterized by a permeability of less than 20 percent, a porosity of from 5 to 15 volume percent, a bulk density greater than 3.6 grams/cc, a wear index of less than 0.1, and an erosion rate of less than 0.020 cc/gram-of-erodant.
An abradable seal assembly for gas turbine engines, said seal characterized by a permeability of less than 20 percent, a porosity of from 5 to 15 volume percent, a bulk density of from 3.8 to 5.2 grams/cc, a wear index of less than 0.1, and an erosion rate of less than 0.020 cc/gram-of-erodant, wherein said seal comprises a metallic substrate, a bond coat, and a plasma sprayed abradable layer comprising from 20 to 45 volume percent hexagonal boron nitride and 50 to 65 volume percent nickel base superalloy having an oxidation resistance greater than that of nichrome and containing both yttrium and hafnium.
Dependencies are inferred from the claim text.