Method for repairing a thermal barrier coating and repaired coating formed thereby
First Claim
1. A method for repairing a thermal barrier coating on a component that has suffered localized spallation of the thermal barrier coating, the method comprising the steps of:
- applying a ceramic paste on a surface area of the component exposed by the localized spallation, the ceramic paste comprising a ceramic powder in a binder, the ceramic powder comprising alumina and zirconia, the binder being chosen from the group consisting of ceramic precursor binders that thermally decompose to form a refractory material; and
then heating the binder to yield a repair coating that covers the surface area of the component, the repair coating comprising the ceramic powder in a matrix that comprises the refractory material formed by reacting the binder.
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Accused Products
Abstract
A method of repairing a thermal barrier coating on a component designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The method more particularly involves repairing a thermal barrier coating on a component that has suffered localized spallation of the thermal barrier coating. After cleaning the surface area of the component exposed by the localized spallation, a ceramic paste comprising a ceramic powder in a binder is applied to the surface area of the component. The binder is then reacted to yield a ceramic-containing repair coating that covers the surface area of the component and comprises the ceramic powder in a matrix of a material formed when the binder was reacted. The binder is preferably a ceramic precursor material that can be converted immediately to a ceramic or allowed to thermally decompose over time to form a ceramic, such that the repair coating has a ceramic matrix. The repair method can be performed while the component remains installed, e.g., in a gas turbine engine. Immediately after the reaction step, the gas turbine engine can resume operation during which the binder is further reacted/converted and the strength of the repair coating increases.
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Citations
17 Claims
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1. A method for repairing a thermal barrier coating on a component that has suffered localized spallation of the thermal barrier coating, the method comprising the steps of:
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applying a ceramic paste on a surface area of the component exposed by the localized spallation, the ceramic paste comprising a ceramic powder in a binder, the ceramic powder comprising alumina and zirconia, the binder being chosen from the group consisting of ceramic precursor binders that thermally decompose to form a refractory material; and
thenheating the binder to yield a repair coating that covers the surface area of the component, the repair coating comprising the ceramic powder in a matrix that comprises the refractory material formed by reacting the binder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for repairing a thermal barrier coating on a component installed in a gas turbine engine and which has suffered localized spallation of the thermal barrier coating so as to expose a surface area defined at least in part by an oxide scale on the component, the method comprising the steps of:
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without removing the component from the gas turbine engine, cleaning the surface area of the component exposed by the localized spallation so as to remove contaminants without damaging the oxide scale;
applying a ceramic paste on the surface area of the component, the ceramic paste comprising a ceramic powder in a ceramic precursor binder dissolved in a solvent, the ceramic powder comprising at last one ceramic material chosen from the group consisting of alumina, zirconia, hafnia, magnesia and silica, the binder being chosen from the group consisting of phosphate-based compositions;
evaporating the solvent and heating the ceramic paste to yield a ceramic-containing repair coating that covers the surface area of the component, the repair coating comprising the ceramic powder in a matrix consisting of a phosphate glass material formed by thermal decomposition of the binder; and
thenoperating the gas turbine engine during which the phosphate glass material forms ceramic-to-ceramic bonds with the ceramic powder. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification