Abstract: Methods for preparing ceramic matrix composites using melt infiltration are provided as well as the resulting ceramic matrix composites. The methods and products include the incorporation of a non-wetting coating to one or more sacrificial fibers. The one or more sacrificial fibers are removed, such as decomposed during pyrolysis, resulting in the formation of a plurality of functional features, in the form of regular and elongate channels along the ceramic matrix composite. During the removing of the one or more sacrificial fibers, the non-wetting coating remains on an interior surface of the plurality of functional features to block infiltration of an infiltrant to the plurality of functional features and deposition thereon. Alternatively, the sacrificial fibers may be removed subsequent to melt infiltration.

Abstract: Systems and methods for manufacturing unidirectional fiber prepreg tapes for CMC articles are provided. In one exemplary aspect, the method includes casting a matrix material on a carrier film to form a matrix film. The matrix material of the matrix film is then allowed to dry for a predetermined time. The matrix film is then wrapped on a drum and the matrix material is wet to a predetermined viscosity with a solvent. Thereafter, a fiber tow that includes of a plurality of fibers is wound about the drum so that the fiber tow penetrates into the matrix material and the matrix material impregnates the fiber tow to form the prepreg tape.

Abstract: Systems and methods for manufacturing unidirectional fiber prepreg tapes for CMC articles are provided. In one exemplary aspect, the method includes casting a matrix material on a carrier film to form a matrix film. The matrix material of the matrix film is then allowed to dry for a predetermined time. The matrix film is then wrapped on a drum and the matrix material is wet to a predetermined viscosity with a solvent. Thereafter, a fiber tow that includes of a plurality of fibers is wound about the drum so that the fiber tow penetrates into the matrix material and the matrix material impregnates the fiber tow to form the prepreg tape.

Abstract: A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

Abstract: A process for inhibiting delamination in a bend of a component formed of a continuous fiber-reinforced composite material having layers containing arrays of unidirectional fibrous elements in a matrix material. A preform of the component is formed by laying-up prepreg tapes corresponding to layers of the component. Each tape contains a matrix precursor, a binder, and an array of the fibrous elements. The tapes are laid-up so that the fibrous elements of at least a first tape traverse the bend, and the fibrous elements lie in planes that are not perpendicular to the axis of curvature of the bend. The preform then undergoes thermal processing, during which delamination of the layers in the bend is inhibited as a result of none of the fibrous elements lying in a plane perpendicular to the axis of curvature of the bend.

Abstract: A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

Abstract: A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

Abstract: In a method of coating a CMC fiber, a multiplicity of fiber tows aligned as a ribbon are simultaneously passed through a reactor and a flow of fiber coating reactant is passed though the reactor to coat the tow fibers. A coating system comprises a reactor chamber to accommodate a multiplicity of fiber tows passing along a path substantially parallel to a longitudinal axis of the chamber and a flow of fiber coating reactant and an aligning structure at an end of the chamber to maintain the multiplicity of fiber tows in a narrow, elongated ribbon configuration. An article comprises a multiplicity of fiber tows aligned in a longitudinal planar array in the form of a ribbon.

Abstract: A method for repairing an article made of a fiber-reinforced ceramic matrix composite comprises attaching sections of a fiber-reinforced tape to the damaged area and then infiltrating the sections with the ceramic matrix or ceramic matrix precursor material. The material around the damaged area may be removed first to form a depression that is then filled with sections of the fiber-reinforced tape and further infiltrated with the ceramic matrix or ceramic matrix precursor material. The repaired article shows stress-strain curve similar to a defect-free article.

Abstract: A method for repairing an article made of a fiber-reinforced ceramic matrix composite comprises attaching sections of a fiber-reinforced tape to the damaged area and then infiltrating the sections with the ceramic matrix or ceramic matrix precursor material. The material around the damaged area may be removed first to form a depression that is then filled with sections of the fiber-reinforced tape and further infiltrated with the ceramic matrix or ceramic matrix precursor material. The repaired article shows stress-strain curve similar to a defect-free article.

Abstract: A method for producing shaped articles of ceramic composites provides a high degree of dimensional tolerance to these articles. A fiber preform is disposed on a surface of a stable formed support, a surface of which is formed with a plurality of indentations, such as grooves, slots, or channels. Precursors of ceramic matrix materials are provided to the fiber preform to infiltrate from both sides of the fiber preform. The infiltration is conducted under vacuum at a temperature not much greater than a melting point of the precursors. The melt-infiltrated composite article substantially retains its dimension and shape throughout the fabrication process.

Abstract: A method for producing shaped articles of ceramic composites provides a high degree of dimensional tolerance to these articles. A fiber preform is disposed on a surface of a stable formed support, a surface of which is formed with a plurality of indentations, such as grooves, slots, or channels. Precursors of ceramic matrix materials are provided to the fiber preform to infiltrate from both sides of the fiber preform. The infiltration is conducted under vacuum at a temperature not much greater than a melting point of the precursors. The melt-infiltrated composite article substantially retains its dimension and shape throughout the fabrication process.