Boron Carbide CMC Manufacturing for Faster Densification
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Solution Overview
Problem
Existing methods for manufacturing ceramic matrix composites (CMCs) face challenges such as prolonged processing times, residual silicon content, and inadequate thermal performance, particularly in aerospace applications, which affect the heat capacity and densification of brake components.
Innovation Solution
A manufacturing process that involves pressure casting, sintering, and densifying a fibrous preform with a slurry comprising boron carbide, followed by sintering the fibrous preform, and densifying the fibrous preform using a liquid source of carbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical vapor infiltration (CVI) or polymer impregnation and pyrolysis (PIP) methods are used to manufacture CMC components, then the composite structure is achieved, but the processing time extends well over 100 hours
Solution Approach 1:
The patent changes the processing parameters by using slurry infiltration at atmospheric pressure followed by sintering at 1800-2000°C, replacing the time-consuming CVI or PIP processes. This parameter change reduces processing time from over 100 hours to a much shorter duration while achieving comparable composite structure quality through the sintering process that densifies the infiltrated slurry.
Solution Approach 2:
The patent replaces the complex chemical vapor infiltration or polymer pyrolysis systems with a simpler slurry infiltration and sintering system. The mechanical slurry infiltration process followed by thermal sintering substitutes for the lengthy chemical or thermal-chemical processes of CVI and PIP, achieving the same composite formation with reduced time and process complexity.
2Loss of time
If melt infiltration (MI) method is used to manufacture CMC components, then the processing time is reduced, but residual silicon is generated which limits upper use temperature
Solution Approach 1:
The patent changes the material composition parameter by using boron carbide instead of silicon-based materials in the slurry infiltration process. This parameter change eliminates the generation of residual silicon while maintaining the rapid processing advantage of infiltration methods. The sintering process then densifies the boron carbide-containing composite without introducing harmful residual elements.
3Manufacturing precision
If conventional CMC fabrication methods are used, then the composite is formed, but inordinately high temperatures are required to achieve proper densification or thermal requirements are not met
Solution Approach 1:
The patent uses a composite slurry containing boron carbide particles infiltrated into a fibrous preform. The boron carbide acts as a sintering aid that enables densification at reduced temperatures compared to conventional CMC methods. The composite nature of the slurry (combining binder and boron carbide) facilitates lower temperature processing while achieving proper densification and meeting thermal requirements.
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
The process includes pressure casting, sintering, and densifying the fibrous preform with the slurry comprising boron carbide, followed by sintering the fibrous preform with the slurry comprising boron carbide, followed by sintering the fibrous preform using a liquid source of carbon.
Implementation Method 1
pressure casting the fibrous preform with the slurry
Implementation Method 2
sintering the boron carbide comprises heat treating the fibrous preform at a temperature of between plus or minus 5% of 1650 °C and 2000 °C
Implementation Method 3
densifying the fibrous preform comprises heat treating the fibrous preform at a temperature of plus or minus 5% of 1600 °C
Data Source
Figure 1A
Figure 1B
Figure 2~3
AI summary
A method of manufacturing a ceramic matrix composite component includes pressure casting (210) a fibrous preform with a slurry comprising boron carbide and densifying (220) the fibrous preform using a liquid source of carbon. The method may include forming holes in the fibrous preform before pressure casting the fibrous preform with the slurry. The method may also include sintering the boron carbide after the pressure casting. In various embodiments, the sintering may be performed before the densifying.