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    Methods to eliminate mudcracks in CMC matrix by humidity controlled atmosphere
    3.
    发明授权
    Methods to eliminate mudcracks in CMC matrix by humidity controlled atmosphere 有权

    公开(公告)号：US12233572B2

    公开(公告)日：2025-02-25

    申请号：US17015840

    申请日：2020-09-09

    Applicant: Rolls-Royce High Temperature Composites Inc.

    Inventor： Pathikumar Sellappan ,  Sungbo Shim

    IPC: B28B11/24 ,  C04B35/64

    Abstract: Methods of reducing dry crack formation in ceramic matrix composite green bodies are provided. Some of the methods expose the green body to a gaseous atmosphere at a relatively high humidity for a first period, and then slowly lower the humidity over a second period, where the gaseous atmosphere is at room temperature for both periods. Other methods start the gaseous atmosphere at room temperature and then raise the temperature to a higher temperature while the humidity is relatively high, and hold that temperature even as the humidity is lowered in the second period.

    METHOD TO FABRICATE A MACHINABLE CERAMIC MATRIX COMPOSITE
    4.
    发明申请
    METHOD TO FABRICATE A MACHINABLE CERAMIC MATRIX COMPOSITE 有权

    公开(公告)号：US20220169574A1

    公开(公告)日：2022-06-02

    申请号：US17412686

    申请日：2021-08-26

    Applicant: Rolls-Royce High Temperature Composites Inc.

    Inventor： Sungbo Shim ,  Pathikumar Sellappan

    IPC: C04B35/80 ,  C04B35/657 ,  C04B35/628 ,  C04B35/626 ,  F01D5/28 ,  F01D25/00

    Abstract: A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the porous ceramic multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is more readily machinable than an inner portion of the surface coating. The outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

    METHODS TO ELIMINATE MUDCRACKS IN CMC MATRIX BY HUMIDITY CONTROLLED ATMOSPHERE
    5.
    发明申请
    METHODS TO ELIMINATE MUDCRACKS IN CMC MATRIX BY HUMIDITY CONTROLLED ATMOSPHERE 有权

    公开(公告)号：US20210069931A1

    公开(公告)日：2021-03-11

    申请号：US17015840

    申请日：2020-09-09

    Applicant: Rolls-Royce High Temperature Composites Inc.

    Inventor： Pathikumar Sellappan ,  Sungbo Shim

    IPC: B28B11/24 ,  C04B35/64

    Abstract: Methods of reducing dry crack formation in ceramic matrix composite green bodies are provided. Some of the methods expose the green body to a gaseous atmosphere at a relatively high humidity for a first period, and then slowly lower the humidity over a second period, where the gaseous atmosphere is at room temperature for both periods. Other methods start the gaseous atmosphere at room temperature and then raise the temperature to a higher temperature while the humidity is relatively high, and hold that temperature even as the humidity is lowered in the second period.

    METHOD TO PRODUCE A PROTECTIVE SURFACE LAYER HAVING A PREDETERMINED TOPOGRAPHY ON A CERAMIC MATRIX COMPOSITE
    6.
    发明申请
    METHOD TO PRODUCE A PROTECTIVE SURFACE LAYER HAVING A PREDETERMINED TOPOGRAPHY ON A CERAMIC MATRIX COMPOSITE 有权

    公开(公告)号：US20210032172A1

    公开(公告)日：2021-02-04

    申请号：US16524397

    申请日：2019-07-29

    Applicant: Rolls-Royce High Temperature Composites Inc.

    Inventor： Sungbo Shim ,  Pathikumar Sellappan

    IPC: C04B41/87 ,  C04B35/83 ,  C04B41/45 ,  C04B41/50

    Abstract: A method to produce a protective surface layer having a predetermined topography on a ceramic matrix composite is described. The method includes applying a slurry layer to a surface of a fiber preform, and drying the slurry layer to form a particulate layer. A surface of the particulate layer is machined to improve surface smoothness and to form a machined surface. A ceramic tape is attached to the machined surface, and a tool comprising one or more features to be imprinted is placed on the ceramic tape, thereby forming a compression assembly. Heat and pressure are applied to the compression assembly to consolidate and bond the ceramic tape to the machined surface, while the one or more features of the tool are imprinted. Thus, a protective surface layer having a predetermined topography is formed.

    METHOD TO FABRICATE A MACHINABLE CERAMIC MATRIX COMPOSITE
    7.
    发明申请
    METHOD TO FABRICATE A MACHINABLE CERAMIC MATRIX COMPOSITE 有权

    公开(公告)号：US20240408855A1

    公开(公告)日：2024-12-12

    申请号：US18807812

    申请日：2024-08-16

    Applicant: Rolls-Royce High Temperature Composites, Inc.

    Inventor： Sungbo Shim ,  Pathikumar Sellappan

    IPC: B32B18/00 ,  B32B37/20

    Abstract: A method to form a machinable ceramic matrix composite comprises forming a porous ceramic multilayer on a surface of a fiber preform. In one example, the porous ceramic multilayer comprises a gradient in porosity in a direction normal to the surface. In another example, the porous ceramic multilayer includes low-wettability particles having a high contact angle with molten silicon, where an amount of the low-wettability particles in the porous ceramic multilayer varies in a direction normal to the surface. After forming the multilayer, the fiber preform is infiltrated with a melt, and the melt is cooled to form a ceramic matrix composite with a surface coating thereon. An outer portion of the surface coating is machined to form a ceramic matrix composite having a machined surface with a predetermined surface finish and/or dimensional tolerance.

    METHOD TO REPAIR CMC COMPONENTS
    9.
    发明申请
    METHOD TO REPAIR CMC COMPONENTS 有权

    公开(公告)号：US20210147303A1

    公开(公告)日：2021-05-20

    申请号：US17088897

    申请日：2020-11-04

    Applicant: Rolls-Royce High Temperature Composites Inc.

    Inventor： Camila S. Bortoluzzi ,  Sungbo Shim ,  Pathikumar Sellappan

    IPC: C04B35/80 ,  C04B35/628 ,  C04B35/657

    Abstract: A method of producing a CMC component that includes forming a preform having a plurality of ceramic fiber plies with each ply occupying a predetermined position; rigidizing the preform with a fiber interphase coating; inspecting the preform to determine which of the plies has partially or fully delaminated; reworking the delaminated plies in the preform; infiltrating a ceramic slurry into the preform to form a green body; optionally, conducting a secondary operation on the green body; and infiltrating the green body with a molten silicon or silicon alloy to form the CMC component. The step of reworking delaminated plies may also be applied to a green body formed after ceramic slurry infiltration into a rigidized fiber preform.

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