C/C Composite Brake Disk Fabrication via Simultaneous CVI
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Solution Overview
Problem
The existing method for fabricating carbon/carbon (C/C) composite friction parts, such as airplane brake disks, incorporating a zirconium-based ceramic phase is complex and lengthier due to the need for separate steps involving zirconium insertion and heat treatment, which are disassociated from the pyrolytic carbon densification process.
Innovation Solution
A method that densifies a carbon yarn fiber preform with a matrix comprising pyrolytic carbon and a ZrOxCy phase using either film-boiling or chemical vapor infiltration, where a zirconium complex with alcoxy or carboxylate ligands is used as a precursor, allowing for simultaneous formation of both phases and omitting additional steps like impregnation and heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zirconium insertion is performed as a separate liquid process step after pyrolytic carbon densification by CVI, then the ZrOxCy phase can be introduced into the friction part, but the fabrication process becomes more complex and lengthier
Solution Approach 1:
The patent combines the zirconium insertion process with the pyrolytic carbon densification process by using a dual-precursor system (carbon precursor and zirconium complex precursor) that are introduced simultaneously during CVI. This merging of previously separate processes eliminates the need for additional liquid impregnation steps and associated heat treatments, thereby reducing fabrication complexity while maintaining the desired ZrOxCy phase incorporation for tribological performance.
Solution Approach 2:
The CVI process is made multi-functional by enabling it to simultaneously perform both pyrolytic carbon matrix formation and zirconium-based ceramic phase incorporation. The use of a zirconium complex precursor with specific ligands allows the same thermal processing step to achieve multiple objectives: carbon matrix densification and ceramic phase formation, eliminating the need for separate specialized process steps.
2Reliability
If separate impregnation with sol and heat treatment steps are added to introduce zirconium, then the ZrOxCy phase is obtained, but the fabrication time increases
Solution Approach 1:
The patent implements continuous useful action by maintaining the CVI process as an uninterrupted thermal treatment that simultaneously achieves carbon matrix formation and zirconium precursor decomposition. The dual-precursor system undergoes pyrolysis in a continuous manner during the same heating cycle, eliminating the need for separate impregnation and heat treatment steps, thus maintaining wear resistance while accelerating fabrication.
Solution Approach 2:
The invention changes the chemical parameters of the precursor system by using a zirconium complex with specific ligands (alcoxy or carboxylate) that decompose at CVI processing temperatures. This parameter change allows the zirconium precursor to be incorporated and transformed into the ZrOxCy phase directly during the carbon matrix formation process, eliminating the need for additional thermal processing steps and improving fabrication speed.
3Manufacturing precision
If multiple separate process steps are used for zirconium insertion, then the ZrOxCy phase distribution can be controlled, but the manufacturing time increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the dual-precursor system with appropriate stoichiometry and chemical composition before the CVI process begins. The zirconium complex precursor is designed with ligands that ensure controlled decomposition and phase formation during the single thermal treatment, pre-establishing the conditions for uniform ZrOxCy phase distribution within the carbon matrix without requiring multiple adjustment steps.
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 simplifies the fabrication process while maintaining the desired tribological performance and wear resistance of the friction parts, making it more efficient than the prior art.
Implementation Method 1
densifying a carbon yarn fiber preform with a matrix comprising at least pyrolytic carbon and a ZrOxCy phase, the matrix being formed by film-boiling or by chemical vapor infiltration from a first precursor for pyrolytic carbon and a second precursor that includes zirconium
Implementation Method 2
densifying a carbon yarn fiber preform with a matrix comprising at least pyrolytic carbon and a ZrOxCy phase, the matrix being formed by film-boiling or by chemical vapor infiltration
Implementation Method 3
a first precursor for pyrolytic carbon... the pyrolytic carbon and the ZrOxCy phase are both formed by using the same process
Data Source
AI summary
A method of fabricating a friction part out of composite material, the method including densifying a carbon yarn fiber preform with a matrix including at least pyrolytic carbon and a ZrOxCy phase, where 1≤x≤2 and 0≤y≤1, the matrix being formed by film-boiling or by chemical vapor infiltration from a first precursor for pyrolytic carbon and a second precursor that includes zirconium, the second precursor being a zirconium complex including an alcoxy or carboxylate ligand bonded to zirconium.