Abstract: A method and masking assembly for masking a dovetail portion of a turbine blade during coating of an airfoil portion of the blade. The masking assembly comprises at least two masking members, each having an exterior surface and an oppositely-disposed undulatory surface complementary to one of oppositely-disposed undulatory surfaces of the dovetail portion. By mating the masking members, the undulatory surfaces thereof define an interior cavity within the masking assembly that accommodates the dovetail portion, and the undulatory surfaces of the masking members contact the undulatory surfaces of the dovetail portion to entrap the dovetail portion within the interior cavity of the masking assembly.

Abstract: A method and masking assembly for masking a dovetail portion of a turbine blade during coating of an airfoil portion of the blade. The masking assembly comprises at least two masking members, each having an exterior surface and an oppositely-disposed undulatory surface complementary to one of oppositely-disposed undulatory surfaces of the dovetail portion. By mating the masking members, the undulatory surfaces thereof define an interior cavity within the masking assembly that accommodates the dovetail portion, and the undulatory surfaces of the masking members contact the undulatory surfaces of the dovetail portion to entrap the dovetail portion within the interior cavity of the masking assembly.

Abstract: A method and masking assembly for masking a dovetail portion of a turbine blade during coating of an airfoil portion of the blade. The masking assembly comprises at least two masking members, each having an exterior surface and an oppositely-disposed undulatory surface complementary to one of oppositely-disposed undulatory surfaces of the dovetail portion. By mating the masking members, the undulatory surfaces thereof define an interior cavity within the masking assembly that accommodates the dovetail portion, and the undulatory surfaces of the masking members contact the undulatory surfaces of the dovetail portion to entrap the dovetail portion within the interior cavity of the masking assembly.

Abstract: A process for forming a coating on a surface of a substrate, in which the heating source for the coating process is microwave radiation so that heating of the coating material is selective and sufficient to melt and bond the coating material to the substrate without excessively heating the substrate. The process entails forming a coating material containing powder particles that are sufficiently small to be highly susceptible to microwave radiation. The coating material is applied to a surface of the substrate and subjected to microwave radiation so that the powder particles within the coating material couple with the microwave radiation and sufficiently melt to form a coating on the substrate surface. The microwave radiation is then interrupted to allow the coating to cool, solidify, and mechanically bond to the substrate.

Abstract: A process for forming diffusion aluminide coatings on an uncoated surface of a substrate, without interdiffusing a sufficient amount of aluminum into a coating layer to adversely affect the coating growth potential and mechanical properties of said coating layer. A metal substrate is provided comprising an external surface and an internal passage therein defined by an internal surface, at least a portion of the external surface of the substrate being coated with a coating layer selected from the group consisting of ?-NiAl-base, MCrAlX, a line-of-sight diffusion aluminide, a non-line-of-sight diffusion aluminide, a pack diffusion aluminide, and a slurry diffusion aluminide on said substrate. The metal substrate is subjected to an aluminum vapor phase deposition process.

Abstract: An article having an internal passage therein and an internal article surface is coated by providing a coating slurry that is a mixture of a deposition source including a source of aluminum, a halide activator, and a flowable carrier comprising a flowable compound selected from the group consisting of a flowable organic compound and a flowable inorganic compound. There is no oxide dispersant in the coating slurry. The coating slurry is introduced into the internal passage and dried to remove at least a portion of the carrier therefrom and leave a dried coating material. The article surface in gaseous communication with the dried coating material is heated to form an aluminum-containing coating bonded to the article surface. Any residual dried coating material is removed by blowing compressed air through the internal passage.

Abstract: A method for applying an aluminide coating on a gas turbine engine blade having an external surface and an internal cooling cavity having an internal surface that is connected to the external surface by cooling holes. The method is conducted in a vapor coating container having a hollow interior coating chamber, and includes the steps of loading the coating chamber with the blade to be coated; providing an aluminide coating gas in the loaded coating chamber; maintaining the loaded coating chamber comprising the aluminide coating gas at a specified temperature and time to deposit an aluminide coating on the external surface of the blade; and then flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified gas flow rate and time to move the aluminide coating gas through the cooling holes and internal cooling cavity and deposit an aluminide coating on the internal surface of the blade.

Abstract: A surface of an article is protected by coating the surface with a silicon-containing coating by preparing a coating mixture of silicon, a halide activator, and an oxide powder, positioning the surface of the article in gaseous communication with the coating mixture, and heating the surface of the article and the coating mixture to a coating temperature of from about 1150° F. to about 1500° F. The article is preferably a component of a gas turbine engine made of a nickel-base superalloy.

Abstract: A method for applying an aluminide coating on a gas turbine engine blade having an external surface and an internal cooling cavity having an internal surface that is connected to the external surface by cooling holes. The method is conducted in a vapor coating container having a hollow interior coating chamber, and includes the steps of loading the coating chamber with the blade to be coated; providing an aluminide coating gas in the loaded coating chamber; flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified gas flow rate and time to move the aluminide coating gas through the cooling holes and internal cooling cavity and deposit an aluminide coating on the internal surface of the blade; and then flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified higher temperature and time to deposit an aluminide coating on the external surface of the blade.

Abstract: The present invention is process for forming diffusion aluminide coatings on an uncoated surface of a substrate, without interdiffusing a sufficient amount of aluminum into a coating layer to adversely affect the coating growth potential and mechanical properties of said coating layer. A metal substrate is provided comprising an external surface and an internal passage therein defined by an internal surface, at least a portion of the external surface of the substrate being coated with a coating layer selected from the group consisting of &bgr;-NiAl-base, MCrAlX, a line-of-sight diffusion aluminide, a non-line-of-sight diffusion aluminide, a pack diffusion aluminide, and a slurry diffusion aluminide on said substrate. The external surface of the substrate is cleaned. The metal substrate is subjected to a aluminum vapor phase deposition process performed using a fluorine-containing activator selected from the group consisting of AiF3, CrF3, NH4F, and combinations thereof, at a rate in the range of about 0.

Abstract: A method for applying an aluminide coating on a gas turbine engine blade having an external surface and an internal cooling cavity having an internal surface that is connected to the external surface by cooling holes. The method is conducted in a vapor coating container having a hollow interior coating chamber, and includes the steps of loading the coating chamber with the blade to be coated; providing an aluminide coating gas in the loaded coating chamber; flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified gas flow rate and time to move the aluminide coating gas through the cooling holes and internal cooling cavity and deposit an aluminide coating on the internal surface of the blade; and then flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified higher temperature and time to deposit an aluminide coating on the external surface of the blade.

Abstract: A method for applying an aluminide coating on a gas turbine engine blade having an external surface and an internal cooling cavity having an internal surface that is connected to the external surface by cooling holes. The method is conducted in a vapor coating container having a hollow interior coating chamber, and includes the steps of loading the coating chamber with the blade to be coated; providing an aluminide coating gas in the loaded coating chamber; maintaining the loaded coating chamber comprising the aluminide coating gas at a specified temperature and time to deposit an aluminide coating on the external surface of the blade; and then flowing an inert carrier gas into the loaded coating chamber comprising the aluminide coating gas at a specified gas flow rate and time to move the aluminide coating gas through the cooling holes and internal cooling cavity and deposit an aluminide coating on the internal surface of the blade.

Abstract: A surface of an article is protected by coating the surface with a silicon-containing coating by preparing a coating mixture of silicon, a halide activator, and an oxide powder, positioning the surface of the article in gaseous communication with the coating mixture, and heating the surface of the article and the coating mixture to a coating temperature of from about 1150° F. to about 1500° F. The article is preferably a component of a gas turbine engine made of a nickel-base superalloy.

Abstract: An article having an internal passage therein and an internal article surface is coated by providing a coating slurry that is a mixture of a deposition source including a source of aluminum, a halide activator, and a flowable carrier comprising a flowable compound selected from the group consisting of a flowable organic compound and a flowable inorganic compound. There is no oxide dispersant in the coating slurry. The coating slurry is introduced into the internal passage and dried to remove at least a portion of the carrier therefrom and leave a dried coating material. The article surface in gaseous communication with the dried coating material is heated to form an aluminum-containing coating bonded to the article surface. Any residual dried coating material is removed by blowing compressed air through the internal passage.

Abstract: A method for applying substantially stoichiometric NiAl to the surface of a superalloy substrate. These coatings are applied to substrates subjected to high temperatures and thermal cycling by providing a powder of the substantially stoichiometric material with the desired minor additions of rare earth elements, Cr or Zr. The coatings are applied by a thermal spray process utilizing hydrogen as a fuel while generating a highly reducing flame. The thermal spray method melts the powder and directs it onto the surface of the turbine component that is to be coated. The powder size is carefully controlled to prevent oxidation of the powder while providing a controlled surface finish. The surface roughness of the bond coat is further mechanically worked to a predetermined surface finish prior to application of the ceramic thermal barrier layer by a PVD method.