Ceramic Component Joining by Reaction Bonding for Complex CMC Shapes
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Solution Overview
Problem
Fabricating large CMC components with complex geometry in a single piece is challenging due to difficulties in achieving acceptable yields, necessitating improved methods for joining densified ceramic components without compromising mechanical properties.
Innovation Solution
A method involving the use of a braze reactant layer with ceramic precursor compounds, infiltrate sources, and pack materials to join densified ceramic components, where the braze reactant layer reacts with molten silicon to form a unified ceramic component, allowing for more complex shapes and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large CMC components with complex geometry are fabricated in a single piece, then mechanical properties are improved, but manufacturing difficulty and yield increase significantly
Solution Approach 1:
The invention divides the complex ceramic component into multiple densified ceramic components that can be manufactured separately using conventional techniques, then joins them together through reaction bonding to form a unified structure. This segmentation allows each component to be produced within feasible manufacturing limits while achieving the overall complex geometry through assembly.
Solution Approach 2:
The invention uses composite material systems combining densified ceramic components with reaction bonding materials (such as silicon-based infiltrants) to create a joined structure. The composite approach allows different materials to contribute their strengths - the densified ceramics provide structural integrity while the reaction bonding material creates strong interfacial connections.
2Ease of manufacture
If conventional joining methods are used for ceramic components, then assembly is simple, but mechanical properties at the joint are compromised
Solution Approach 1:
The invention changes the physical and chemical parameters of the joining process by heating the assembled components to high temperatures (typically 1000-1600°C) to enable reaction bonding. This parameter change transforms the joining mechanism from mechanical or low-temperature bonding to high-temperature chemical reaction bonding, which creates much stronger joints capable of withstanding the demanding service conditions of ceramic components.
Solution Approach 2:
The invention utilizes phase transitions of the bonding material (such as silicon melting and infiltrating the ceramic interfaces) during the reaction bonding process. The bonding material transitions from solid to liquid phase, flows into the interfaces between densified ceramic components, and then re-solidifies to form strong metallurgical or chemical bonds, significantly improving joint strength.
3Shape
If densified ceramic components are joined together, then complex shapes can be achieved, but the joining process complexity increases
Solution Approach 1:
The invention segments the complex geometry into multiple manufacturable densified ceramic components that can be assembled in various configurations. This allows the final complex shape to be achieved through assembly of simpler sub-components rather than attempting to manufacture the entire complex geometry in one piece, which would be prohibitively difficult.
Solution Approach 2:
The invention introduces reaction bonding materials as intermediaries between the densified ceramic components. These intermediary materials facilitate the joining process by reacting with the ceramic surfaces to form strong bonds, simplifying the overall joining process compared to direct ceramic-to-ceramic bonding which would require extremely complex and difficult-to-control processes.
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
Enables the formation of unitary ceramic components with unified constructions, enhancing mechanical properties and allowing for the creation of complex shapes without complicated ply layup processes, suitable for high-temperature applications like gas turbine engines.
Implementation Method 1
heating the at least one infiltrate source, the pack material, the first densified ceramic component, and the second densified ceramic component to a braze temperature that is at or above a melting point of at least one phase of the infiltrate composition such that the at least one phase of infiltrate composition melts and flows into the braze reactant layer
Implementation Method 2
reacts with the ceramic precursor compound to form a ceramic material, the ceramic material joining the first densified ceramic component and the second densified ceramic component
Data Source
AI summary
Methods for forming a unitary ceramic component are provided. The method may include: positioning a braze reactant layer in a contact area between a first densified ceramic component and a second densified ceramic component; positioning a pack material around at least a portion of the first densified ceramic component or the second densified ceramic component; positioning at least one infiltrate source in fluid communication with the braze reactant layer; and thereafter, heating the at least one infiltrate source, the pack material, the first densified ceramic component, and the second densified ceramic component to a braze temperature that is at or above a melting point of at least one phase of the infiltrate composition such that at least one phase of infiltrate composition melts and flows into the braze reactant layer and reacts with a ceramic precursor compound therein to form a ceramic material.