Abstract:
An article may include a substrate that comprises a nickel alloy. The substrate may include a modified subsurface region and a bulk region. The modified subsurface region may include a first composition and the bulk region may include a second composition different than the first composition. The modified subsurface region may include at least one of a reactive element or a noble metal, and the modified subsurface region comprises a thickness of less than about 0.3 µm measured in a direction substantially normal to a surface of the substrate. The modified subsurface region may be formed by depositing a layer including at least one of the reactive element or the noble metal in a layer on a surface of the substrate and introducing the at least one of the reactive element or the noble metal into the modified subsurface region using ion bombardment.
Abstract:
An article may include an array of features formed in a substrate and may be coated with a coating layer. The array of features may mitigate stress experienced by the coated article. In particular, the array of features may reduce or limit crack propagation at the interface between the substrate and the coating layer. In some examples, the article is an airfoil that includes a tip that defines an edge. An array of features is formed on the surface of the tip, where the array of features is proximate to the edge, and the array of features does not intersect the edge. The airfoil includes a coating layer formed on the surface of the tip and the array of features. FIG.4,14B,14C
Abstract:
An article may include a substrate including a ceramic or a CMC; a bond layer on the substrate; and a diffusion barrier layer between the substrate and the bond layer. The diffusion barrier layer may include at least one of molybdenum metal, tantalum metal, tungsten metal, or niobium metal. In some examples, the article may include a stabilizing layer that includes at least one of a silicide of molybdenum (MoSi2), tantalum (TaSi2), tungsten (WSi2), or niobium (NbSi2), between the diffusion barrier layer and the bond layer.
Abstract:
An article may include an array of features formed in a substrate and may be coated by a thermal barrier coating (TBC). The array of features may mitigate thermal stress experienced by the coated article. In particular, the array of features may reduce or limit crack propagation at or above the interface of a thermally insulative layer and a bond coat in the TBC. In some embodiments, the array may be formed proximate to and substantially aligned with cooling holes formed in the substrate. In other embodiments, an article may include a first array of features formed in a first location of a substrate and a second array of features formed in a second location of a substrate. The first and second locations may be determined or selected based on a prediction of thermal stresses that the substrate will experience at the first and second locations during use. FIG. 1B
Abstract:
An article may include an array of features formed in a substrate and may be coated with a coating layer. The array of features may mitigate stress experienced by the coated article. In particular, the array of features may reduce or limit crack propagation at the interface between the substrate and the coating layer. In some examples, the article is an airfoil that includes a tip that defines an edge. An array of features is formed on the surface of the tip, where the array of features is proximate to the edge, and the array of features does not intersect the edge. The airfoil includes a coating layer formed on the surface of the tip and the array of features.
Abstract:
An article may include a substrate including a metal or alloy; a bond coat directly on the substrate; an intermediate ceramic layer on the bond coat; and an abradable ceramic layer directly on the intermediate ceramic layer. The intermediate ceramic layer includes a stabilized tetragonal prime phase constitution and defines a first porosity. The abradable ceramic layer includes zirconia or hafnia stabilized in the tetragonal prime phase by a second mixture including between about 5 wt. % and about 10 wt. % ytterbia, between about 0.5 wt. % and about 2.5 wt. % samaria, and between about 1 wt. % and about 4 wt. % of at least one of lutetia, scandia, ceria, neodymia, europia, or gadolinia, and a balance zirconia or hafnia. The abradable ceramic layer defines a second porosity, and the second porosity is higher than the first porosity.
Abstract:
A method may include introducing a suspension including a coating material and a carrier into a heated plume of a thermal spray device. The coating material may include silicon or a silicon alloy. The method may further include directing the coating material toward a substrate using the heated plume, in which the substrate includes a ceramic or a ceramic matrix composite. The method may include depositing the coating material in a bond coat directly on the substrate, where the bond coat has a porosity of less than about 3 volume percent.
Abstract:
A barrier coating for isolating a metallic support component from a composite component in a gas turbine engine is provided. The barrier coating may be applied to the metallic support component so that when the ceramic component is mounted on the metallic support component the barrier coating is engaged.