Methods for tape deposition of a sacrificial coating on a CMC substrate are provided. The method comprises: applying a matrix material onto a surface of a film; drying the matrix material to remove the solvent; and transferring the dried matrix material from the film to the CMC substrate. The matrix material comprises a mixture of a rare earth silicate powder, a sintering aid, and a solvent.

Methods for tape deposition of a sacrificial coating on a CMC substrate are provided. The method comprises: applying a matrix material onto a surface of a film; drying the matrix material to remove the solvent; and transferring the dried matrix material from the film to the CMC substrate. The matrix material comprises a mixture of a rare earth silicate powder, a sintering aid, and a solvent.

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 making a ceramic matrix composite article includes fabricating a preform comprising a plurality of fibers arranged in an arrangement, wherein there are spaces between adjacent ones of the fibers; providing particles to the preform, whereby the particles are situated in the spaces; and applying a matrix material to the preform by atomic layer deposition to make a ceramic matrix composite article. A ceramic matrix composite article is also disclosed.

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 coating system on a CMC substrate is provided, along with methods of its tape deposition onto a substrate. The coating system can include a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a first sacrificial coating of a first reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; a second sacrificial coating of a second reinforced rare earth silicate matrix on the second rare earth silicate coating; a third rare earth silicate coating on the second sacrificial coating; and an outer layer on the third rare earth silicate coating. The first sacrificial coating and the second sacrificial coating have, independently, a thickness of about 4 mils to about 40 mils.

A coating system on a CMC substrate is provided, along with methods of its tape deposition onto a substrate. The coating system can include a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a first sacrificial coating of a first reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; a second sacrificial coating of a second reinforced rare earth silicate matrix on the second rare earth silicate coating; a third rare earth silicate coating on the second sacrificial coating; and an outer layer on the third rare earth silicate coating. The first sacrificial coating and the second sacrificial coating have, independently, a thickness of about 4 mils to about 40 mils.

Coating systems are provided for use on a CMC substrate, that can include: a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a sacrificial coating of a reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; and an outer layer on the second rare earth silicate coating. The first rare earth silicate coating comprises at least one rare earth silicate layer, and the second rare earth silicate coating comprises at least one rare earth silicate layer. The sacrificial coating has a thickness of about 4 mils to about 40 mils. Methods are also provided for tape deposition of a sacrificial coating on a CMC substrate.

Coating systems are provided for use on a CMC substrate, that can include: a bond coat on a surface of the CMC substrate; a first rare earth silicate coating on the bond coat; a sacrificial coating of a reinforced rare earth silicate matrix on the at least one rare earth silicate layer; a second rare earth silicate coating on the sacrificial coating; and an outer layer on the second rare earth silicate coating. The first rare earth silicate coating comprises at least one rare earth silicate layer, and the second rare earth silicate coating comprises at least one rare earth silicate layer. The sacrificial coating has a thickness of about 4 mils to about 40 mils. Methods are also provided for tape deposition of a sacrificial coating on a CMC substrate.

A fixture for processing a ceramic matrix composite article includes first and second tool segments that each have an exterior side and an interior side. The interior side has a border mate face, and the interior side of the first tool segment faces the interior side of the second tool segment such that the border mate faces align and circumscribe a working region for holding a fiber preform that is to be coated with a ceramic material. The tool segments each having an array of through-holes that open to the working region to permit inflow of gaseous precursor into the working region. A seal circumscribes the working region and blocks a gap between the border mate faces to limit inflow of the gaseous precursor through the gap into the working region.