A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

An article for high temperature service is presented herein. One embodiment is an article including a substrate having a silicon-bearing ceramic matrix composite; and a layer disposed over the substrate, wherein the layer includes silicon and a dopant, the dopant including aluminum. In another embodiment, the article includes a ceramic matrix composite substrate, wherein the composite includes a silicon-bearing ceramic and a dopant, the dopant including aluminum; a bond coat disposed over the substrate, where the bond coat includes elemental silicon, a silicon alloy, a silicide, or combinations including any of the aforementioned; and a coating disposed over the bond coat, the coating including a silicate (such as an aluminosilicate or rare earth silicate), yttria-stabilized zirconia, or a combination including any of the aforementioned.

A bypass valve assembly for a turbine generator includes a valve body, bypass seats, valve stem, valve cap, bypass valve disc, bypass valves, and pressure seal head. The valve body defines a central bore and a plurality of passageways. Each passageway has an inlet smaller than its outlet. Each bypass seat is within the inlet of a corresponding passageway. The bypass seats have a higher wear resistance than the valve body. The valve stem is within the central bore. The valve cap is secured to the valve body. The bypass valve disc is secured to the valve stem. Each bypass valve has a base portion and a nose portion. Each nose portion defines a contoured surface area with a wear coating and extends into a corresponding passageway. The pressure seal head is disposed around the valve stem and defines steps having a wear coating.

A ceramic matrix composite includes a ceramic matrix, fibers embedded in the ceramic matrix, and an interfacial coating system on each of the fibers. The interfacial coating system includes alternating layers of boron nitride layers of individual thicknesses of about 50 nanometers to 200 nanometers and carbon layers of individual thicknesses of less than 5 nanometers.

An article for high temperature service is presented herein. One embodiment is an article including a substrate having a silicon-bearing ceramic matrix composite; and a layer disposed over the substrate, wherein the layer includes silicon and a dopant, the dopant including aluminum. In another embodiment, the article includes a ceramic matrix composite substrate, wherein the composite includes a silicon-bearing ceramic and a dopant, the dopant including aluminum; a bond coat disposed over the substrate, where the bond coat includes elemental silicon, a silicon alloy, a silicide, or combinations including any of the aforementioned; and a coating disposed over the bond coat, the coating including a silicate (such as an aluminosilicate or rare earth silicate), yttria-stabilized zirconia, or a combination including any of the aforementioned.

A multilayer protective coating system includes a turbine engine component substrate formed of a ceramic matrix composite material, an environmental barrier coating layer including a rare earth disilicate material deposited directly on the substrate, and a plurality of pairs of alternating layers of the rare earth disilicate material and a rare earth monosilicate material deposited and sintered directly on the environmental barrier coating layer. Each layer of the plurality of pairs of alternating layers is relative less thick as compared with the environmental barrier coating layer.

A turbine system including a sealing component is presented. The sealing component includes a ceramic material. The ceramic material includes grains having an average grain size of less than 10 microns. A turbine shroud assembly including the sealing component is also presented.

An environmental barrier coating system for a turbine component, including an environmental barrier layer applied to a turbine component substrate containing silicon; the environmental barrier layer comprising an oxide matrix surrounding a fiber-reinforcement structure and a self-healing phase interspersed throughout the oxide matrix; wherein the fiber-reinforcement structure comprises at least one first fiber bundle oriented along a load bearing stress direction of said turbine component substrate; wherein the fiber-reinforcement structure comprises at least one second fiber bundle oriented orthogonal to the at least one first fiber bundle orientation; wherein the fiber-reinforcement structure comprises at least one third fiber woven between the at least one first fiber bundle and the at least one second fiber bundle.

A seal assembly is disclosed for sealing a high pressure fluid cavity from a low pressure fluid cavity. The cavities are at least partially disposed between a rotatable shaft and a sump housing. The seal assembly comprises a circumferential runner and a seal ring. The circumferential runner is carried by the shaft and has a radially outward facing seal surface extending axially along the shaft. The seal ring is sealing engaged with the sump housing and has a radially inward facing seal surface that sealingly engages the radially outward facing seal surface of the runner. The runner and the seal ring are formed from materials having coefficients of thermal expansion that are matched to effect sealing engagement between the runner and the seal ring over a predetermined range of operating temperatures.

An article for high temperature service is presented herein. One embodiment is an article including a substrate having a silicon-bearing ceramic matrix composite; and a layer disposed over the substrate, wherein the layer includes silicon and a dopant, the dopant including aluminum. In another embodiment, the article includes a ceramic matrix composite substrate, wherein the composite includes a silicon-bearing ceramic and a dopant, the dopant including aluminum; a bond coat disposed over the substrate, where the bond coat includes elemental silicon, a silicon alloy, a silicide, or combinations including any of the aforementioned; and a coating disposed over the bond coat, the coating including a silicate (such as an aluminosilicate or rare earth silicate), yttria-stabilized zirconia, or a combination including any of the aforementioned.