Carbon/Carbon Preform Rapid Densification With Uniform Induction Heating
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Solution Overview
Problem
Existing methods for producing carbon/carbon composites face bottlenecks in qualified preforms and lengthy densification processes, leading to high costs and long lead times, making them unsuitable for high-demand applications like heatshields and nosecones.
Innovation Solution
A rapid densification process using induction heating with customized coils for non-flat components, allowing uniform heating and reducing densification time from months to days, utilizing a hydrocarbon bath and film boiling to achieve uniform through-thickness densities and low porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional densification processes are used to produce high-quality C/C composites, then manufacturing precision and material quality are improved, but production time and lead time increase to months
Solution Approach 1:
The patent applies parameter changes by modifying the heating method from traditional slow densification to rapid induction heating. The process uses induction heating with power densities of 1-10 kW/kg to heat the preform rapidly to temperatures between 1000-2000°C, achieving densification in hours rather than months. This parameter change in heating rate and temperature profile enables both high-quality C/C composites and dramatically reduced production time.
Solution Approach 2:
The patent replaces traditional mechanical or thermal diffusion-based densification methods with electromagnetic induction heating. The induction heating system uses electromagnetic fields to directly heat the carbon preform through a susceptor, substituting slow thermal conduction with rapid electromagnetic energy conversion. This substitution enables the rapid densification process to achieve high-quality C/C composites in a fraction of the time required by conventional methods.
2Stability of the object's composition
If conventional heating methods are used for preform structures, then heating uniformity is improved, but processing time increases to months
Solution Approach 1:
The patent applies local quality by using customized induction coils designed to match the specific geometry of the preform. The coils are configured to provide locally optimized heating zones that account for varying thermal requirements across different regions of the preform. This localized heating approach ensures uniform heating throughout complex geometries while maintaining rapid processing speeds, achieving both heating uniformity and high productivity.
Solution Approach 2:
The patent applies dynamics by implementing a dynamic heating process where induction heating parameters are adjusted during the densification cycle. The process transitions from high-power initial heating to controlled ramp-down phases, with real-time monitoring and adjustment of temperature profiles. This dynamic control enables uniform heating of the entire preform structure while maintaining rapid overall processing time.
3Productivity
If rapid densification is implemented to reduce lead time, then productivity is improved, but heating uniformity and material quality may deteriorate
Solution Approach 1:
The patent uses a susceptor as an intermediary material between the induction heating field and the carbon preform. The susceptor, made of a material with high electromagnetic coupling, efficiently converts electromagnetic energy to thermal energy and distributes it uniformly through the preform structure. This intermediary enables rapid heating while maintaining uniform temperature distribution, achieving both high productivity and consistent density uniformity in the final C/C composite.
Solution Approach 2:
The patent replaces slow thermal conduction-based heating with electromagnetic induction heating to achieve rapid and uniform heating simultaneously. The induction process directly couples electromagnetic energy into the preform through the susceptor, creating uniform volumetric heating throughout the entire preform structure. This substitution enables the rapid densification process to maintain excellent density uniformity (greater than 95% relative density) while reducing processing time from months to hours.
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 significantly reduces production time and cost, enabling high-quality carbon/carbon components with uniform densities and low porosity, suitable for complex shapes and thick-walled structures, and achieves comparable mechanical properties to traditional methods.
Implementation Method 1
Special induction heating methods use customized coils to provide desired heating across non-flat components
Implementation Method 2
allow for the uniform heating of preform structures
Data Source
AI summary
A method of producing a densified carbon fiber reinforced carbon (carbon/carbon) component includes placing a carbon/carbon preform and preform heater(s) into a reactor vessel with an immersing quantity of a precursor liquid (e.g., hydrocarbon). The reactor vessel includes a condenser for condensing precursor gases (e.g., carbonaceous gases) produced during densification and thereby maintain a thermodynamic equilibrium. Electrical current is supplied to the preform heater over a multi-hour period of densification in which the precursor liquid is continually boiled and the precursor gases continually produced. The current is sufficient to maintain the preform at a densification temperature above a precursor cracking temperature, thereby causing the precursor gases to be diffused into the preform and dissociated gas species to be deposited. Densification begins within the preform and advances outwardly along a densification front until completion.