An article may include a substrate defining at least one at least partially obstructed surface. The substrate includes at least one of a ceramic or a ceramic matrix composite. The article also may include an environmental barrier coating on the at least partially obstructed substrate. The environmental barrier coating includes a layer including a rare earth disilicate and a microstructure comprising closed porosity.

An airfoil includes an airfoil wall that defines a leading end, a trailing end, and suction and pressure sides that join the leading end and the trailing end. The airfoil wall is formed of a silicon-containing ceramic. A first environmental barrier topcoat is disposed on the suction side of the airfoil wall, and a second, different environmental barrier topcoat is disposed on the pressure side of the airfoil wall. The first topcoat is vaporization-resistant and the second topcoat is resistant to calcium-magnesium-aluminosilicate.

A protection method protects at least one hollow internal area of a turbine engine part made of a superalloy from oxidation and/or corrosion, wherein the at least one hollow inner area has been formed by means of at least one core made of a ceramic material limited by an external surface that surrounds it. Before bringing the superalloy around the core made of a ceramic material, the external surface is coated with a material that includes a nanometric layer of hafnium (Hf), and/or a micrometric layer of platinum (Pt), or

a mixture at least of hafnium and platinum.

A boundary layer turbine (BLT) engine has a housing formed by an outer cylinder a first and a second faceplate, a turbine shaft through the faceplates, a stack of alternating disks and spacers with central holes joined to the turbine shaft leaving an outer combustion zone, an air inlet through the first faceplate, an exhaust port through the second faceplate, a fuel port through the outer cylinder, and an ignition device communicating with the combustion zone. The disks and spacers have openings forming separate intake and exhaust channels parallel to the turbine shaft, one channel channeling air from the air inlet port to spaces between disks, and the other channel channeling exhaust from the combustion zone through the exhaust channel to the exhaust port. Fuel is injected into the combustion zone, the air fuel mixture is ignited, and exhaust products impart torque to the turbine shaft by boundary layer friction.

A seal system includes a ceramic component that has a non-core-gaspath surface region that defines a first surface roughness and a core gaspath surface region. A metallic component is situated adjacent the non-core-gaspath surface region. A coating system is disposed on the ceramic component. The coating system includes a silicon-containing layer on the non-core-gaspath surface region and a barrier layer that has a first section on the silicon-containing layer and a second section on the core-gaspath region and that is connected to the first section. The surface of the barrier layer has a second surface roughness that is less than the first surface roughness. The first section is in contact with the metallic component and the second section serves as an environmental barrier on the core-gaspath region.

A coated component, along with methods of its formation and use, is provided. The coated component may include a substrate having a surface with a plurality of cavities defined therein, a bond coating (e.g., including a silicon material) on the surface of the substrate within the cavities, and an environmental barrier coating over the surface of the substrate and encasing the bond coating within the cavities such that the bond coating, when melted, is contained within the cavities. Such a coated component may be, in one embodiment, a turbine component, such as a CMC component for use in a hot gas path of a gas turbine engine.

A method for processing a component is provided and includes masking a first portion of the component with a maskant. The maskant includes a slurry having a plurality of particles in a fluid carrier. The plurality of particles comprises at least one of silicon, carbon, one or more rare earth disilicates, monosilicates or oxides, and combinations thereof. The method includes depositing a silicon-based coating on a second portion of the component via a chemical vapor deposition process and removing the maskant and any overlying silicon-based coating from the first portion of the component.

A seal system includes a ceramic component, a metallic component, a coating system. The ceramic component has a first surface region that defines a first surface roughness. The metallic component is situated adjacent to the first surface region and has a second surface region facing the first surface region. The coating system includes a silicon-containing layer on the surface region of the ceramic component and barrier layer on the silicon-containing layer. The silicon containing layer has a surface in contact with the barrier layer and the barrier layer has a surface in contact with the metallic component. The surface of the barrier layer has a second surface roughness that is less than the first surface roughness. The barrier layer serves to limit interaction between silicon of the silicon-containing layer and elements of the metallic component. The barrier layer includes at least one of mullite, zircon, or hafnon.

A coated substrate is provided that includes an environmental barrier coating on (e.g., directly on) a surface of a substrate (e.g., a ceramic matrix composite). The environmental barrier coating can include a barrier layer having a refractory material phase and a silicon-containing glass phase. The silicon-containing glass phase may be a continuous phase within the barrier layer (e.g., a breathable grain boundary of the barrier layer), or may be a plurality of discontinuous layers dispersed throughout the refractory material phase. The refractory material phase can include a rare earth silicate material having a rare earth component at a first atomic percent, while the silicon-containing glass phase comprises the rare earth component at a second atomic percent that is less than the first atomic percent. Methods are also provided for forming a barrier layer on a substrate.

A coated component, along with method of forming the same, is provided. The coated component may include a substrate having a surface, a silicon-based bond coating on the surface of the substrate, and an EBC on the silicon-based bond coating. The silicon-based bond coating may include a silicon-phase contained within a refractory phase. The silicon-phase, when melted, is contained within the refractory phase and between the surface of the substrate and an inner surface of the environmental barrier coating. Such a coated component may be, in particular embodiments, a turbine component.