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 turbine engine rotor component, such as a compressor or turbine disk or seal element, is protected from corrosion by depositing an aluminum or chromium coating on the component. The deposition can be performed by a vapor deposition process, such as metal organic chemical vapor deposition (MOCVD), to a coating thickness of from about 0.2 to about 50 microns, typically from about 0.5 to about 3 microns. In one embodiment, 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 component to be coated; and flowing a tri-alkyl aluminum or chromium carbonyl coating gas into the loaded coating chamber at a specified temperature, pressure, and time to deposit an aluminum or chromium coating on the surface of the component. The coated component is then heated in a nonoxidizing atmosphere to a specified temperature to form an aluminide or chromide coating on the surface.

Abstract: An internal coating on an internal passage wall exposed at a passage opening through an article external surface is protected from removal during repair of the article, including removal of at least a portion of an external coating, by a masking assembly disposed about the passage opening. The masking assembly comprises a masking member and a substantially flexible seal, substantially inert to a coating removal medium for the external coating. The masking member is shaped for disposition about the passage opening across a gap between the external surface and the masking member. The substantially flexible seal is disposed across the gap substantially to seal the gap.

Abstract: A bond coat process for thermal barrier coatings. The method includes, after cleaning and masking the external surface of the substrate, first applying a layer of NiCrZr alloy to the external surface of the substrate using a sputter coat or other suitable process. Aluminum is then applied to the substrate, using either a vapor phase aluminization (VPA) or chemical vapor deposition (CVD) process, wherein aluminum diffuses into the NiCrZr alloy layer wherein a diffusion layer is formed by the aluminum with the substrate material on the internal surface of the substrate. The coated substrate may then be subjected to a heat treatment in a protective atmosphere to further allow diffusion of the aluminide into the NiAlCrZr diffusion layer. The substantially Al outer layers of the NiAlCrZr diffusion layer, and the diffusion aluminide layer, will provide an aluminum source for the surface, which will oxidize to form a tightly adherent aluminum scale.

Abstract: A process of removing ceramic deposits from a surface hole in a component, a particular example being portions of a ceramic coating deposited on a surface of a component equipped with cooling holes. The process makes use of a pulsed Nd:YAG laser operated with parameters that avoid delamination, cracking or otherwise damaging a ceramic coating surrounding a cooling hole. The laser is operated to generate a laser beam that removes some of the ceramic deposit from the hole while a residual portion of the ceramic deposit remains surrounding the hole to define a surface opening.

Abstract: Apparatus and method to improve vapor phase diffusion coating of articles. The apparatus provides a barrier to segregate the portion of the article requiring coating from the portion of the article not requiring coating. The fixture is reusable, being unaffected by the coating gases. The fixture reduces the exposure of the coating gases with the portion of the article not requiring coating. By use of an optional seal, the portion of the article not requiring coating can be isolated from the coating gases.

Abstract: A method is provided for refurbishing a service operated metallic coating on a substrate alloy, the coating including at least within a coating outer surface at least one oxide chemically grown from at least one coating element, for example Al, and chemically bonded with the coating outer surface as a result of thermal exposure during service operation. Growth of the oxide has depleted at least a portion of the coating element from the coating. The method comprises removing the oxide from the coating outer surface while substantially retaining the metallic coating, thereby exposing in the coating outer surface at least one surface void that had been occupied by the oxide. The retained metallic coating is mechanically worked, substantially without removal of the retained coating, to close the void, providing a treated metallic coating surface over which a refurbishing coating is applied.

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 coated article has a metallic substrate with a substrate composition, and a metallic coating overlying and contacting the metallic substrate. The metallic coating has a metallic-coating composition different from the substrate composition. A protective coating overlies and contacts the metallic coating. The protective coating includes a chromium aluminide layer overlying and contacting the metallic coating, and optionally a thermal barrier coating overlying and contacting the chromium aluminide layer. This structure may be used to restore a key dimension of an article that has previously been in service and to protect the article as well.

Abstract: A process of removing ceramic deposits from a surface hole in a component, a particular example being portions of a ceramic coating deposited on a surface of a component equipped with cooling holes. The process makes use of a pulsed Nd:YAG laser operated with parameters that avoid delamination, cracking or otherwise damaging a ceramic coating surrounding a cooling hole. The laser is operated to generate a laser beam that removes some of the ceramic deposit from the hole while a residual portion of the ceramic deposit remains surrounding the hole to define a surface opening.

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 coated article has a metallic substrate with a substrate composition, and a metallic coating overlying and contacting the metallic substrate. The metallic coating has a metallic-coating composition different from the substrate composition. A protective coating overlies and contacts the metallic coating. The protective coating includes an aluminide layer overlying and contacting the metallic coating, and optionally a thermal barrier coating overlying and contacting the aluminide layer. This structure may be used to restore a key dimension of an article that has previously been in service and to protect the article as well.

Abstract: Apparatus and method to improve vapor phase diffusion coating of articles. The apparatus provides a barrier to segregate the portion of the article requiring coating from the portion of the article not requiring coating. The fixture is reusable, being unaffected by the coating gases. The fixture reduces the exposure of the coating gases with the portion of the article not requiring coating. By use of an optional seal, the portion of the article not requiring coating can be isolated from the coating gases.

Abstract: A method for applying diffusion aluminide coating on a selective area of a turbine engine component and the coating produced by that method is disclosed. A quartz infrared lamp heats only substantially the localized area of the component to be coated, rather than the complete part. Either halide activated or non-activated tape is applied on the area to be coated and is held in place during coating using a high temperature dimensionally stable tape holder manufactured from graphite or ceramic. The quartz infrared lamp is used to heat only the desired area to a coating temperature of about 1800° F. to about 2000° F. under an inert atmosphere for about 3 to about 8 hours to achieve the desired aluminide coating thickness. No powder masking of the machined surface area is required. Due to the localized heating, aluminum vapor generated from the tape will only deposit aluminide coating on the taped area.

Abstract: A method for applying, in a non-oxidizing atmosphere, a diffusion aluminide coating to a metallic surface of an article combines use of a relatively low aluminide coating temperature in the range of about 1650-1800° F. with a relatively high Al activity Al source material including Al of at least about 40 weight %. Such combination results in an as-deposited aluminide coating comprising a diffusion portion bonded between a metallic substrate and a coating outer portion of a thickness of no greater than about 60% of the thickness of the coating outer portion, typically less than about 1 mil.

Abstract: A method for applying diffusion aluminide coating on a selective area of a turbine engine component and the coating produced by that method is disclosed. A quartz infrared lamp heats only substantially the localized area of the component to be coated, rather than the complete part. Either halide activated or non-activated tape is applied on the area to be coated and is held in place during coating using a high temperature dimensionally stable tape holder manufactured from graphite or ceramic. The quartz infrared lamp is used to heat only the desired area to a coating temperature of about 1800° F. to about 2000° F. under an inert atmosphere for about 3 to about 8 hours to achieve the desired aluminide coating thickness. No powder masking of the machined surface area is required. Due to the localized heating, aluminum vapor generated from the tape will only deposit aluminide coating on the taped area.

Abstract: An internal coating on an internal passage wall exposed at a passage opening through an article external surface is protected from removal during repair of the article, including removal of at least a portion of an external coating, by a masking assembly disposed about the passage opening. The masking assembly comprises a masking member and a substantially flexible seal, substantially inert to a coating removal medium for the external coating. The masking member is shaped for disposition about the passage opening across a gap between the external surface and the masking member. The substantially flexible seal is disposed across the gap substantially to seal the gap.

Abstract: An internal passage of an article such as a gas turbine airfoil is coated with an aluminum-containing coating. To accomplish this coating process, a coating slurry of a mixture of a carrier component of water and a hectorite clay or a bentonite clay, together with a solids component of a source of aluminum, a halide activator, and an oxide dispersant, is prepared. The coating slurry is applied to the internal passage of the gas turbine airfoil and dried. The gas turbine airfoil and the applied coating slurry are heated to form an aluminum-containing coating bonded to the internal passage of the gas turbine airfoil. Excess coating material is removed from the article internal passage.

Abstract: An internal coating on an internal passage wall exposed at a passage opening through an article external surface is protected from removal during repair of the article, including removal of at least a portion of an external coating, by a masking assembly disposed about the passage opening. The masking assembly comprises a masking member and a substantially flexible seal, substantially inert to a coating removal medium for the external coating. The masking member is shaped for disposition about the passage opening across a gap between the external surface and the masking member. The substantially flexible seal is disposed across the gap substantially to seal the gap.

Abstract: A method for applying, in a non-oxidizing atmosphere, a diffusion aluminide coating to a metallic surface of an article combines use of a relatively low aluminide coating temperature in the range of about 1650-1800° F. with a relatively high Al activity Al source material including Al of at least about 40 weight %. Such combination results in an as-deposited aluminide coating comprising a diffusion portion bonded between a metallic substrate and a coating outer portion of a thickness of no greater than about 60% of the thickness of the coating outer portion, typically less than about 1 mil.