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AssigneeGeneral Electric Company
InventorsYuk-Chiu Lau, Farshad Ghasripoor, Dennis M. Gray, Chek Beng Ng
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An abradable coating composition for use on shrouds in gas turbine engines (or other hot gas path metal components exposed to high temperatures) containing an initial porous coating phase created by adding a “fugitive polymer” (such as polyester or polyimide) to the base metal alloy, together with a brittle intermetallic phase such as β-NiAl that serves to increase the brittle nature of the metal matrix, thereby increasing the abradability of the coating at elevated temperatures, and to improve the oxidation resistance of the coating at elevated temperatures. Coatings having about 12 wt % polyester has been found to exhibit excellent abradability for applications involving turbine shroud coatings. An abradable coating thickness in the range of between 40 and 60 ml provides the best performance for turbine shrouds exposed to gas temperatures between 1380° F. and 1850° F. Abradable coatings in accordance with the invention can be used for new metal components or to repair existing equipment.
A coating composition for use in forming an abradable coating on metal components of gas turbine shrouds exposed to high temperature environments, comprising about 85-88% by weight of a brittle intermetallic phase of metal aluminide containing β-NiAl in an amount sufficient to increase the oxidation resistance of said coating at temperatures in the range of about 1380° F. to 1850° F. while maintaining good abradability, and about 12-15% by weight of a fugitive polymer consisting of polyester or polyimide, said fugitive polymer being present in an mount sufficient to adjust the porosity and abradability of said coating as applied to said metal components.
A coating composition for use in forming an abradable coating on metal components of gas turbine shrouds exposed to high temperature environments, comprising a brittle intermetallic phase of metal aluminide containing β-NiAl in an amount sufficient to increase the oxidation resistance of said coating at elevated temperatures while maintaining good abradability, a metallic oxidation resistant matrix phase consisting of MCrAlY, wherein “M” designates CoNiCrAlY, NiCoCrAlY, FeCrAlY or NiCrAlY, and a fugitive polymer present in an amount sufficient to adjust the porosity and abradability of said coating as applied to said metal components.
An abradable, oxidation resistant coating applied to metal components of gas turbine shrouds exposed to high temperature environments, comprising a laminate structure having a first dense bond coat layer with no added porosity and having a metallic oxidation-resistant alloy containing MCrAlY, wherein “M” designates CoNiCrAlY, NiCoCrAlY, FeCrAlY or NiCrAlY, and a second brittle intermetallic layer of metal aluminide containing β-NiAl in an amount sufficient to increase the oxidation resistance of said coating at temperatures in the range of about 1380° F. to 1850° F., the porosity and abradability of said second brittle intermetallic layer having been adjusted by burning off a fugitive polymer present in said brittle intermetallic layer when applied to said metal components.
An abradable coating applied to metal components of gas turbine shrouds exposed to high temperature environments, comprising a brittle intermetallic phase containing β-NiAl and in an amount sufficient to increase the oxidation life of said coating at elevated temperatures and having the porosity and abradability of said brittle intermetallic phase adjusted by burning off a fugitive polymer when applied to said metal component, wherein the oxidation life of said abradable coating is determined according to the regression formula:
Dependencies are inferred from the claim text.