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Solution Overview
Problem
Current methods for manufacturing carbon/carbon parts, such as C/C brake disks, face challenges in achieving optimal fiber volume ratios and mechanical properties due to limitations in the needling and carbonization processes, which affect the high-temperature performance and durability of the final products.
Innovation Solution
A method involving the superposition and needling of fibrous layers at specific angles, followed by mechanical pressure application before carbonization, to form a fibrous preform with a controlled fiber volume ratio, and subsequent carbonization to convert oxidized polyacrylonitrile fibers into carbon fibers, while densifying the preform with a carbon matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional needling and carbonization processes are used, then manufacturing simplicity is maintained, but fiber volume ratio and mechanical properties are insufficient
Solution Approach 1:
The manufacturing process is divided into distinct stages: needling at first density, carbonization, compression at high temperature, and optional secondary needling. Each stage targets specific properties, allowing precise control of fiber volume ratio without overwhelming process complexity
Solution Approach 2:
The preform is needled to a first needle density before carbonization, establishing an initial fiber arrangement that facilitates subsequent compression and densification. This preliminary structuring enables better control of final fiber volume ratio
2Manufacturing precision
If mechanical pressure is applied before carbonization, then fiber volume ratio is increased, but processing complexity increases
Solution Approach 1:
Mechanical pressure is applied at a specific temperature range (below carbonization temperature) to compress the preform before the chemical transformation of carbonization. This parameter timing optimizes fiber volume ratio while keeping the process manageable
3Strength
If fiber volume ratio is increased through compression, then mechanical properties improve, but manufacturing complexity increases
Solution Approach 1:
The preform is needled to a first needle density before carbonization, establishing an initial fiber arrangement that facilitates subsequent compression and densification. This preliminary structuring enables better control of final fiber volume ratio
Solution Approach 2:
Compression is applied at a controlled temperature range (below carbonization temperature) to achieve optimal fiber volume ratio. The temperature and pressure parameters are carefully managed to improve mechanical properties without excessive complexity
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 enhances the fiber volume ratio and mechanical properties of the carbon/carbon parts, resulting in improved high-temperature performance and durability, specifically increasing the friction coefficient and wear resistance of brake disks.
Implementation Method 1
carbonizing the fibrous preform by heating the fibrous preform to convert fibers of the fibrous preform into carbon fibers
Implementation Method 2
compressing the fibrous preform, wherein the fiber volume ratio of the fibrous preform after the carbonizing is between about 20% to 24% fiber volume
Implementation Method 3
The method may further comprise densifying the fibrous preform by depositing a carbon matrix within at least a portion of the pores
Data Source
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AI summary
A method for forming a fibroud preform (26) is described comprising A method for forming a fibrous preform (26) comprising superposing a first fibrous layer (12) aligned in a machine direction with an additional fibrous layer (12) aligned in an acute angle to the machine direction; needling the first fibrous layer and the additional fibrous layer together at a needle density of between approximately 60 and 65 needle punches per square centimeter to form a first combined fibrous mat; superposing an additional combined fibrous mat with the first combined fibrous mat; needling the first combined fibrous mat and the additional combined fibrous mat at a needle density of between approximately 45 and 55 needle punches per square centimeter to form the fibrous preform comprising oxidized polyacrylonitrile (OPF) fibers extending in multiple directions and having pores extending therethrough, wherein a fiber volume ratio of the fibrous preform is between about 30% fiber volume and about 35% fiber volume; compressing the fibrous preform; and carbonizing the fibrous preform by heating the fibrous preform to convert fibers of the fibrous preform (26) into carbon fibers, wherein the fiber volume ratio of the fibrous preform after the carbonizing is between about 20% to 24% fiber volume.