An example method for forming a high temperature coating includes depositing a carbon layer on to a surface of a composite article using chemical vapor deposition. The composite substrate includes a composite substrate including a carbon matrix. The surface of the composite article includes one or more surface voids. The method further includes applying a metal slurry to the surface of the composite article following the deposition of the carbon layer and reacting a metal of the metal slurry with carbon of the carbon layer to form an antioxidant layer of a metal carbide on the composite article.

A tooling fixture is disclosed for densification by chemical vapor infiltration of a fiber preform of a ceramic matrix composite. The tooling fixture includes a body having oppositely disposed first and second surfaces and a plurality of holes extending between the first and second surfaces, and a coating. The first surface is configured to be disposed adjacent to the fiber preform. The coating is disposed on the first surface and surfaces defining the plurality of holes. The coating comprises at least one of a ceramic material, hexagonal boron nitride, turbostratic boron nitride, and graphite.

A tooling fixture is disclosed for densification by chemical vapor infiltration of a fiber preform of a ceramic matrix composite. The tooling fixture includes a body having oppositely disposed first and second surfaces and a plurality of holes extending between the first and second surfaces, and a coating. The first surface is configured to be disposed adjacent to the fiber preform. The coating is disposed on the first surface and surfaces defining the plurality of holes. The coating comprises at least one of a ceramic material, hexagonal boron nitride, turbostratic boron nitride, and graphite.

A method of producing a melt infiltrated ceramic matrix composite (CMC) article that includes the steps of: forming a ceramic fiber preform; optionally, rigidizing the ceramic fiber preform with a fiber interphase coating via a Chemical Vapor Infiltration (CVI) process, infiltrating a ceramic slurry into the porous body or preform, conducting one or more secondary operations, and finally, melt infiltrating the preform with molten silicon or a silicon alloy to form the CMC article. The infiltration of a ceramic slurry into a ceramic fiber preform to form a green body is performed along with the use of convection and/or conduction as heat transfer mechanisms, such that the ceramic slurry does not require the incorporation of a pre-gelation material in order for the slurry to remain within the green body during subsequent processing steps.

A fiber comprises a bulk material comprising one or more materials selected from the group consisting of carbon, silicon, boron, silicon carbide, and boron nitride; and a metal whose affinity for oxygen is greater than the affinity for oxygen of any of the one or more materials. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium. At least a first portion of the metal may be present in un-oxidized form at the entrance to and/or within grain boundaries within the fiber.

A method of improving at least one of the strength, creep resistance, and toughness of a fiber comprises adding to a fiber, initially comprising a bulk material having a first affinity for oxygen, a metal that has a second affinity for oxygen higher than the first affinity. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium.

A fiber comprises a bulk material comprising one or more materials selected from the group consisting of carbon, silicon, boron, silicon carbide, and boron nitride; and a metal whose affinity for oxygen is greater than the affinity for oxygen of any of the one or more materials. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium. At least a first portion of the metal may be present in un-oxidized form at the entrance to and/or within grain boundaries within the fiber.

A method of improving at least one of the strength, creep resistance, and toughness of a fiber comprises adding to a fiber, initially comprising a bulk material having a first affinity for oxygen, a metal that has a second affinity for oxygen higher than the first affinity. The metal may be selected from the group consisting of beryllium, titanium, hafnium and zirconium.

A method of forming a ceramic matrix composite includes three-dimensionally weaving a fibrous preform, the preform including a plurality of warp tows, a plurality of weft tows, and a plurality of z-fibers passing orthogonally between the plurality of warp and the plurality of weft tows. The method further includes debulking the preform, decomposing the plurality of z-fibers to form a respective plurality of z-channels in the preform, and densifying the preform with a ceramic matrix.

A tooling fixture suitable for use in infiltrating a fibrous preform with a flow of reactant gas includes an outer surface and an inner surface defining a thickness therebetween, and a plurality of holes extending through the thickness of the tooling fixture. The plurality of holes includes a first hole having cylindrical geometry with a first pair of dimensions comprising a first length and a first diameter, a second hole having cylindrical geometry with a second pair of dimensions comprising a second length and a second diameter, and a third hole having cylindrical geometry with a third pair of dimensions comprising a third length and a third diameter. At least one dimension of the first pair of dimensions is different from at least one dimension of the second pair of dimensions, and at least one dimension of the second pair of dimensions is different from at least one dimension of the third pair of dimensions.

A mandrel suitable for supporting an airfoil preform includes a first piece extending along a longitudinal axis of the mandrel, and a second piece in physical contact with the first piece at first interface region and extending along the longitudinal axis of the mandrel. The first piece is formed from a first material, and the second piece is formed from a second material.

A method can include applying a mask to a CMC structure, and subjecting the structure having an applied mask to a process for repair. In one embodiment, the applying a mask to a CMC structure can include applying a mask to a feature of a CMC structure.