A silica composite particle includes a silica particle and a compound in which a metal atom selected from the group consisting of Ti, Al, Zr, V, and Mg bonds to an organic group through oxygen, the silica particle being surface-treated with the compound. A coverage of a surface of the silica composite particle with the metal atom is 0.01 at % or more and 30 at % or less. When a binding energy peak of O1s in an oxide of the metal atom is assumed to be MO1s, a binding energy peak of O1s in SiO.sub.2 is assumed to be SO1s, and a binding energy peak of O1s in the silica composite particle is assumed to be MSO1s, the binding energy peaks being detected by X-ray photoelectron spectroscopy, the formula 0.000452X.sup.20.059117X+SO1s<MSOs(SO1sMO1s)/100X+SO1s is satisfied.

The disclosure describes techniques for forming a surface layer of an article including a CMC using a cast. In some examples, the surface layer includes three-dimensional surface features, which may increase adhesion between the CMC and a coating on the CMC. In some examples, the surface layer may include excess material, with or without three-dimensional surface features, which is on the CMC. The excess material may be machined to remove some of the excess material and facilitate conforming the article to dimensional tolerances, e.g., for fitting the article to another component. The excess material may reduce a likelihood that the CMC (e.g., reinforcement material in the CMC) is damaged by the machining.

The disclosure describes techniques for forming a surface layer of an article including a CMC using a cast. In some examples, the surface layer includes three-dimensional surface features, which may increase adhesion between the CMC and a coating on the CMC. In some examples, the surface layer may include excess material, with or without three-dimensional surface features, which is on the CMC. The excess material may be machined to remove some of the excess material and facilitate conforming the article to dimensional tolerances, e.g., for fitting the article to another component. The excess material may reduce a likelihood that the CMC (e.g., reinforcement material in the CMC) is damaged by the machining.

A method of forming a composite component is provided. The method includes locating a fibrous preform, providing a slurry, mixing the slurry with sacrificial fibers, injecting the slurry into the fibrous preform, heating the fibrous preform, forming channels in the fibrous preform, and densifying the fibrous preform. The sacrificial fibers are suspended in the fibrous preform along an injection pathway such that heating the sacrificial fibers forms the channels along the injection pathway as the sacrificial fibers are burned away.

A method of forming a composite component is provided. The method includes locating a fibrous preform, providing a slurry, mixing the slurry with sacrificial fibers, injecting the slurry into the fibrous preform, heating the fibrous preform, forming channels in the fibrous preform, and densifying the fibrous preform. The sacrificial fibers are suspended in the fibrous preform along an injection pathway such that heating the sacrificial fibers forms the channels along the injection pathway as the sacrificial fibers are burned away.

The present invention provides a plasma-resistant ceramic substrate including a bulk of an oxide composition; and a surface layer in which an oxide composition component constituting the bulk was modified to a composition including one or more anions selected from the group consisting of F.sup. and Cl.sup., wherein the surface layer is a layer in which a raw material containing one or more anions selected from the group consisting of F.sup. and Cl.sup. is vaporized by heating and adsorbed on the surface of the ceramic substrate to be modified to a composition including one or more anions selected from the group consisting of F.sup. and Cl.sup., and a method of manufacturing the same. According to the present invention, the plasma resistance and durability of the ceramic substrate can be improved at low cost.

The present invention provides a plasma-resistant ceramic substrate including a bulk of an oxide composition; and a surface layer in which an oxide composition component constituting the bulk was modified to a composition including one or more anions selected from the group consisting of F.sup. and Cl.sup., wherein the surface layer is a layer in which a raw material containing one or more anions selected from the group consisting of F.sup. and Cl.sup. is vaporized by heating and adsorbed on the surface of the ceramic substrate to be modified to a composition including one or more anions selected from the group consisting of F.sup. and Cl.sup., and a method of manufacturing the same. According to the present invention, the plasma resistance and durability of the ceramic substrate can be improved at low cost.

Composite components and methods for adding a composite material to a composite component are provided. For example, a method comprises positioning a composite material segment against the composite component to form a component layup; applying an insulating material around at least a portion of the component layup to form an insulated layup; and densifying the insulated layup, where the composite component was previously densified before positioning the composite material segment against the composite component. In some embodiments, the composite material is ceramic matrix composite (CMC) and the composite material segment is a plurality of CMC plies. The composite component may be a CMC gas turbine engine component that comprises an original CMC component and a new CMC material segment joined to the original CMC component through the transfer of silicon between the original CMC component and the new CMC material segment during melt infiltration.

Composite components and methods for adding a composite material to a composite component are provided. For example, a method comprises positioning a composite material segment against the composite component to form a component layup; applying an insulating material around at least a portion of the component layup to form an insulated layup; and densifying the insulated layup, where the composite component was previously densified before positioning the composite material segment against the composite component. In some embodiments, the composite material is ceramic matrix composite (CMC) and the composite material segment is a plurality of CMC plies. The composite component may be a CMC gas turbine engine component that comprises an original CMC component and a new CMC material segment joined to the original CMC component through the transfer of silicon between the original CMC component and the new CMC material segment during melt infiltration.

A crucible includes an outer element and an inner element. The outer element includes a first portion that is horizontal at a bottom end of the crucible and a second portion that ascends radially outwardly from the bottom end of the crucible to a top end of the crucible at a first acute angle to a vertical axis. The inner element includes a conus with a cylinder at a base of the conus. The conus descends radially outwardly from the top end of the crucible to the bottom end of the crucible at a second acute angle to the vertical axis. The inner element includes a base portion of the cylinder attached to the first portion of the outer element using a sealant to form a hollow mold between an inner portion of the outer element and an outer portion of the inner element.