Ceramic Matrix Composite Repair via Reactive Bonding

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Solution Overview

Problem

Current methods for repairing ceramic matrix composite components in gas turbine engines are limited by high costs and time, and existing technologies do not effectively address the need for efficient repair of non-conformities such as cracks, delamination, and material degradation in high-temperature environments.

Innovation Solution

A method involving mechanical interlocking and reactive processing, where a repair patch is integrated with the component through an equilibrium reaction using alternating layers of constituents like Ti, Zr, Hf, and Si, and applying energy to facilitate a self-propagating reaction, utilizing ultrasonic machining for material removal and creating a bond structure with carbides, borides, and intermetallics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional repair methods are used for ceramic matrix composite components, then the repair can be performed with existing technology, but the repair cost is high and the time required is excessive

Engineering Contradiction:
Improverepair speedVSAvoidrepair time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent changes the chemical state of the bonding interface by applying alternating layers of reactive constituents (Ti, Zr, Hf, Si) that undergo equilibrium reactions at elevated temperatures to form strong intermetallic bonds, carbides, and borides. This chemical transformation enables rapid repair while achieving bond strengths comparable to or exceeding the base material

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent prepares the repair surface in advance by removing the non-conforming portion and creating a mechanically interlocking geometry through ultrasonic machining. The alternating layers of reactive constituents are applied beforehand to the repair patch and component surface, so that when assembled, the equilibrium reaction can proceed immediately upon heating, significantly reducing total repair time

Inventive Principle:
Principle #10Preliminary action

2Strength

If strong bonding is achieved through reactive processing, then structural integrity is enhanced, but the process complexity increases

Engineering Contradiction:
Improvebond strengthVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The bonding interface is segmented into alternating layers of different reactive constituents (Ti, Zr, Hf, Si) with thicknesses of 0.5-5 micrometers each. This segmentation allows each layer to participate in specific equilibrium reactions, creating a gradient of intermediate phases that enhance bond strength while controlling the complexity of the reaction zones

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The alternating layers of reactive constituents act as intermediaries between the ceramic matrix composite repair patch and the base component. These layers undergo equilibrium reactions to form intermediate compounds (carbides, borides, intermetallics) that mediate the bonding process, creating strong chemical bonds while managing the complexity through controlled reaction pathways

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If mechanical interlocking is combined with reactive bonding, then repair reliability is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improverepair reliabilityVSAvoidsurface preparation precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent merges two bonding mechanisms—mechanical interlocking through ultrasonic machining of the repair geometry and chemical bonding through equilibrium reactions of alternating reactive constituent layers. This combination creates redundant bonding pathways, where mechanical interlocking provides immediate structural support while chemical bonds develop during heating, thereby improving reliability without requiring extreme precision in a single mechanism

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient and cost-effective repair of ceramic matrix composite components by forming a strong bond, enhancing structural integrity and reducing production cycles, while accommodating complex geometries and high-temperature operations.

Implementation Method 1

removing a repair volume from the component using ultrasonic machining

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

applying an equilibrium reaction to form a bond structure between the repair patch and the component

Methodology Applied
Scientific EffectEquilibrium reaction: Chemical Bonding

Implementation Method 3

applying energy to facilitate a self-propagating reaction

Methodology Applied
Scientific EffectSelf-propagating reaction: Exothermic Reaction

Data Source

PatentEP2970025B1Ceramic matrix composite repair by reactive processing and mechanical interlocking
Publication Date: 2020.02.12 ROLLS ROYCE CORP
  • EP2970025B1 patent drawingFigure 1
  • EP2970025B1 patent drawingFigure 2
  • EP2970025B1 patent drawingFigure 3a~4b

AI summary

A method for modifying a ceramic matrix component is disclosed including identifying a non-conforming region of a composite component capable of operating in a gas turbine engine; removing at least a portion of the non¬ conforming region to create an exposed surface of the composite component; preparing a preform in response to the removing at least a portion of the non¬ conforming region; applying a reactive constituent surface region to at least one of the exposed surface of the composite component and the preform, the reactive constituent surface region being capable of producing a non-equilibrium condition; positioning the preform to provide a contact region between the exposed surface of the composite component and the preform proximate the reactive constituent surface region; and reacting the reactive constituent surface region in an equilibrium reaction at the contact region to form a bond structure between the exposed surface of the composite component and the preform.