A ceramic matrix composite (CMC) component includes at least one seal surface, the at least one seal surface disposed adjacent an interfacing surface for providing a seal therebetween; and a coating disposed on the seal surface. The coating includes an aluminum oxide and/or a silicon dioxide.

A turbomachine engine including a high-pressure compressor, a high-pressure turbine, a combustion chamber in flow communication with the high-pressure compressor and the high-pressure turbine, and a power turbine in flow communication with the high-pressure turbine. At least one of the high-pressure compressor, the high-pressure turbine, and the power turbine comprises a ceramic matrix composite (CMC) material. The turbomachine engine includes a low-pressure shaft coupled to the power turbine and characterized by a midshaft rating (MSR) between two hundred (ft/sec).sup.1/2 and three hundred (ft/sec).sup.1/2. The low-pressure shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). The turbomachine engine is configured to operate up to the redline speed without passing through a critical speed associated with a first-order bending mode of the low-pressure shaft.

A ceramic heat shield for a gas turbine. The ceramic heat shield has a ceramic body containing aluminium oxide and has a surface layer of the ceramic body which contains yttrium aluminium garnet as reaction coating material. A gas turbine includes such a ceramic heat shield and a method produces such a ceramic heat shield.

Embodiments of the present disclosure generally relate to protective coatings on various substrates including aerospace components and methods for depositing the protective coatings. In one or more embodiments, a method of forming a protective coating on an aerospace component includes forming an aluminum oxide layer on a surface of the aerospace component and depositing a boron nitride layer on or over the aluminum oxide layer during a vapor deposition process. In some examples, the method includes depositing a metal-containing catalytic layer on the aluminum oxide layer before depositing the boron nitride layer. The boron nitride layer can include hexagonal boron nitride (hBN).

A method for manufacturing a coating includes dissolving at least one salt in a mixture of water and ethanol to form a precursor solution, adding an additive to the precursor solution to form a fuel solution, and injecting the fuel solution into a plasma flame. The additive includes at least one of urea or ammonium acetate. The additive functions as a fuel to increase a temperature of the plasma flame. The method further includes manufacturing the coating on a substrate. The coating includes a garnet structure including a predetermined amount of yttrium-aluminum, one or more first cracks extending completely through a thickness of the coating, and a porosity greater than ten volume percent.

A method includes applying a material coating on a surface of a machine component using a thermal spray, wherein the material coating is formed from a combination of a hardfacing material and aluminum-containing particles. The method also includes thermally treating the material coating to generate an oxide layer comprising aluminum from the aluminum-containing particles, wherein the oxide layer is configured to reduce oxidation of the hardfacing material.

A space filler for forming a fibrous preform may comprise an additively manufactured ceramic material. The additively manufactured ceramic material may define a plurality of pores. A shape of the additively manufactured ceramic material may complement a shape of a void formed by fibrous regions of the fibrous preform.

A piston seal assembly for a gas turbine engine includes a seal composed of a nickel-based superalloy; a component in contact with the seal and defining a seal-counterface; and a coating on the seal at the seal-counterface, wherein the coating is a metal alloy binder phase and a hard particle phase distributed through the binder phase.

A method for applying a coating 1 to a surface 2 of a mullite material 3 is specified, which comprises pretreating the surface 2 of the mullite material 3 by means of a plasma-chemical process in which molecular hydrogen is excited in such a way that plasma-activated hydrogen is produced S1, and applying an aluminum oxide-containing layer 4 by means of a PVD process to the pretreated surface 2 of the mullite material 3 S2. Furthermore, a mullite material 3 with a coating and a gas turbine component with such a mullite material 3 are specified.

An alpha-alumina coated turbocharger turbine wheel includes a hub portion, a plurality of blades disposed about the hub portion, each blade of the plurality of blades having a leading edge and a trailing edge, a centerline passing axially through the hub portion, and a back-side wall defined radially between the leading edge of each blade of the plurality of blades and the centerline. The turbocharger turbine wheel is made of a metal alloy and a surface coating layer of alpha-alumina. The surface coating layer of alpha-alumina may be disposed only on the hub portion, the plurality of blades, and a radially-outer portion of the back-side wall. The radially-outer portion is defined between a radial distance from the centerline and the leading edge of each blade of the plurality of blades. Alternatively, the surface coating layer of alpha-alumina may be disposed on the hub portion, the plurality of blades, and an entirety of the back-side wall.