Abstract: A nickel-based braze alloy composition is described, including nickel, about 1 weight % to about 5 weight % boron (B); and about 1 weight % to about 20 weight % germanium (Ge). The composition is free of any silicon. Superalloy articles that contains a crack or other type of void or gap filled with the nickel-based braze alloy composition are also described, along with methods for filling such a gap. Related articles of manufacture and brazing processes to join metal components are also disclosed.

Abstract: A nickel-based braze alloy composition includes nickel, about 1 weight % to about 5 weight % boron (B); and about 1 weight % to about 20 weight % germanium (Ge). The composition is free of any silicon. Superalloy articles having a crack or other type of void or gap may be filled with the nickel-based braze alloy composition. Methods for filling such a gap are described.

Abstract: A nickel-based braze alloy composition is described, including nickel, about 1 weight % to about 5 weight % boron (B); and about 1 weight % to about 20 weight % germanium (Ge). The composition is free of any silicon. Superalloy articles that contains a crack or other type of void or gap filled with the nickel-based braze alloy composition are also described, along with methods for filling such a gap. Related articles of manufacture and brazing processes to join metal components are also disclosed.

Abstract: A turbine nozzle may be repaired by severing the inner band from the vanes and outer band, which may then be discarded. A replacement nozzle is cast to include replacement vanes extending between a replacement outer band and an inner web, with the replacement outer band and vanes conforming with the original outer band and vanes. The new web is configured differently than the old inner band and includes a tie bar. The inner band is machined to form vane seats. The web is machined to form plinths atop the tie bar at each of the replacement vanes. The plinths and tie bar are assembled through the vane seats and bonded to the machined inner band to collectively form the repaired turbine nozzle.

Abstract: Braze materials, brazing processes, and coatings produced therefrom, for example, a wear-resistant coating suitable for protecting surfaces subjected to wear at high temperatures. The braze material includes first particles formed of a metallic alloy and second particles formed of a cobalt-base braze alloy having a melting point below the melting point of the first particles. The braze alloy consists of, by weight, 3.5 to 15.0% silicon, 2.0 to 6.0% boron, and the balance cobalt and incidental impurities, and the second particles constitute at least 30 up to 90 weight percent of the first and second particles combined. Following a brazing cycle performed on the braze material, a wear-resistant coating is formed in which the first particles are dispersed in a matrix of the braze alloy.

Abstract: A turbine nozzle may be repaired by severing the inner band from the vanes and outer band, which may then be discarded. A replacement nozzle is cast to include replacement vanes extending between a replacement outer band and an inner web, with the replacement outer band and vanes conforming with the original outer band and vanes. The new web is configured differently than the old inner band and includes a tie bar. The inner band is machined to form vane seats. The web is machined to form plinths atop the tie bar at each of the replacement vanes. The plinths and tie bar are assembled through the vane seats and bonded to the machined inner band to collectively form the repaired turbine nozzle.

Abstract: A direct metal laser sintered material including a substrate formed from a laser sintering process, the substrate having at least one surface, and a cladding material brazed onto at least a portion of the surface.

Abstract: A method for selectively removing an aluminum-poor overlay coating from a substrate of a component, which as a result of its low aluminum content is highly resistant to a selective stripping solution. The method entails diffusing aluminum into the overlay coating to form an aluminum-infused overlay coating having an increased aluminum level in at least an outer surface thereof. The diffusion step is carried out so that the increased aluminum level is sufficient to render the aluminum-infused overlay coating removable by selective stripping. The outer surface of the aluminum-infused overlay coating is then contacted with an aqueous composition to remove the aluminum-infused overlay coating from the substrate. The aqueous composition includes at least one acid having the formula HxAF6, and/or precursors thereof, wherein A is Si, Ge, Ti, Zr, Al, and/or Ga, and x is from 1 to 6.

Abstract: A method of making a braze preform includes: providing a mixture of a brazing alloy in metallic powder form and a binder; melting the binder and forming the mixture into a preform having a preselected shape; removing a majority of the binder from the preform; and heating the preform to remove the remainder of the binder and to sinter the metallic powder together. The preform may include a wear-resistant material therein. Such preforms may be used to form a braze joint between two metallic components, or to produce a metallic component with a wearcoated surface.

Abstract: A method for repairing a nickel-base superalloy article, such as a gas turbine stationary flowpath shroud having flowpath cooling holes therein that has previously been in service, includes the steps of providing the nickel-base superalloy article that has previously been in service; and applying a restoration to a surface of the article. The restoration is applied by the steps of providing a restoration nickel-base alloy, wherein the restoration nickel-base alloy preferably has no more than about 15 weight percent chromium and no more than about 0.01 percent yttrium, thereafter applying a restoration coating of the restoration nickel-base alloy to the surface of the article by a hyper-velocity oxyfuel metal spray process or a low-pressure plasma spray process, and thereafter heating the article with the restoration coating applied to the surface thereof to a sufficiently high temperature to diffusion bond the restoration coating to the surface of the article. The article is then returned to service.

Abstract: A direct metal laser sintered material including a substrate formed from a laser sintering process, the substrate having at least one surface, and a cladding material brazed onto at least a portion of the surface.

Abstract: A process for heating a braze alloy by microwave radiation so that heating of the alloy is selective and sufficient to cause complete melting of the alloy and permit metallurgical bonding to a substrate on which the alloy is melted, but without excessively heating the substrate so as not to degrade the properties of the substrate. The process entails providing metallic powder particles having essentially the same metallic composition, with at least some of the particles being sufficiently small to be highly susceptible to microwave radiation. A mass of the particles is then applied to a surface of a substrate, after which the mass is subjected to microwave radiation so that the particles within the mass couple with the microwave radiation and sufficiently melt to metallurgically bond to the substrate. The microwave radiation is then interrupted and the mass is allowed to cool, solidify, and form a solid brazement.

Abstract: A method to improve the impact resistance of a braze joint between a tungsten/carbide/cobalt substrate and a substrate including titanium or alloy thereof includes utilizing a brazing material including gold, nickel, and copper present in respective amounts to improve the ductility of the braze joint.

Abstract: A brazing assembly includes a tungsten/carbide/cobalt substrate (e.g., wear pad), a second substrate including titanium or titanium alloy (e.g., a midspan shroud of a fan or compressor blade) and a brazing material including gold, nickel, and copper present in respective amounts to improve the ductility of the braze joint. A brazed article includes a first substrate, a second substrate, and a braze joint having a post-braze hardness of between 450 and 600 KHN. A method to improve the impact resistance of a braze joint between a tungsten/carbide/cobalt substrate and a substrate including titanium or alloy thereof includes utilizing a brazing material including gold, nickel, and copper and brazing at temperatures less than about 1900° F. (1038° C.).

Abstract: A method for repairing a nickel-base superalloy article, such as a gas turbine stationary flowpath shroud having flowpath cooling holes therein that has previously been in service, includes the steps of providing the nickel-base superalloy article that has previously been in service; and applying a restoration to a surface of the article. The restoration is applied by the steps of providing a restoration nickel-base alloy, wherein the restoration nickel-base alloy preferably has no more than about 15 weight percent chromium and no more than about 0.01 percent yttrium, thereafter applying a restoration coating of the restoration nickel-base alloy to the surface of the article by a hyper-velocity oxyfuel metal spray process or a low-pressure plasma spray process, and thereafter heating the article with the restoration coating applied to the surface thereof to a sufficiently high temperature to diffusion bond the restoration coating to the surface of the article. The article is then returned to service.

Abstract: A process for brazing components formed of superalloys that contain elements prone to oxidation during brazing. At least one braze tape is applied to at least one faying surface of at least a first of the components being joined by brazing. The braze tape comprises a braze tape alloy containing the base metal of the superalloys and a melting point suppressant, and is applied so as to substantially cover the faying surface. The braze tape is then bonded to the faying surface by heating the first component to a temperature not exceeding the brazing temperature required to join the components. Thereafter, the components are assembled so that the bonded braze tape are between the respective faying surfaces of the components. The components are then brazed together by applying and heating a braze alloy to the braze temperature.

Abstract: A brazing assembly includes a tungsten/carbide/cobalt substrate (e.g., wear pad), a second substrate including titanium or titanium alloy (e.g., a midspan shroud of a fan or compressor blade) and a brazing material including gold, nickel, and copper present in respective amounts to improve the ductility of the braze joint. A brazed article includes a first substrate, a second substrate, and a braze joint having a post-braze hardness of between 450 and 600 KHN. A method to improve the impact resistance of a braze joint between a tungsten/carbide/cobalt substrate and a substrate including titanium or alloy thereof includes utilizing a brazing material including gold, nickel, and copper and brazing at temperatures less than about 1900° F. (1038° C.).

Abstract: A method for selectively removing an aluminum-poor overlay coating from a substrate of a component, which as a result of its low aluminum content is highly resistant to a selective stripping solution. The method entails diffusing aluminum into the overlay coating to form an aluminum-infused overlay coating having an increased aluminum level in at least an outer surface thereof. The diffusion step is carried out so that the increased aluminum level is sufficient to render the aluminum-infused overlay coating removable by selective stripping. The outer surface of the aluminum-infused overlay coating is then contacted with an aqueous composition to remove the aluminum-infused overlay coating from the substrate. The aqueous composition includes at least one acid having the formula HxAF6, and/or precursors thereof, wherein A is Si, Ge, Ti, Zr, Al, and/or Ga, and x is from 1 to 6.

Abstract: Braze compositions containing flux compositions and processes for using such braze compositions, such as for use in the manufacturing, coating, repair, and build-up of superalloy components. The braze composition contains an aqueous binder system, multiple inorganic compounds, titanium hydride, and a metallic braze alloy. The braze composition is useful when brazing superalloys that are prone to oxidation at elevated brazing temperatures.

Abstract: Methods for manufacturing components capable of transporting a liquid including providing a mold, placing at least one core made from a core material into the mold, injecting a component material into the mold about the core to produce a green component, heating the green component to burn out the core and produce a brown component, and sintering the brown component to produce a finished component capable of transporting a liquid wherein the finished component is from about 95% to about 99% dense.