C/C Composite Brake Disc Wear Resistance via Ceramic Particle Dispersion
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Solution Overview
Problem
Aircraft brake discs made of carbon/carbon composite material experience high wear at low temperatures during cold taxiing braking, and the introduction of ceramic particles to improve wear resistance often consumes carbon from the reinforcement fibers and degrades mechanical properties.
Innovation Solution
A method involving the impregnation of a sol-gel type solution with ceramic compound precursors, followed by heat treatment to achieve dispersion of particles with reduced average size (less than 250 nm) within the composite material, avoiding direct contact with fibers and promoting better dispersion within the carbon matrix, thereby reducing friction wear at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic particles are introduced into the C/C composite material to improve wear resistance, then wear resistance is improved, but carbon from the reinforcement fibers is consumed and mechanical properties are degraded
Solution Approach 1:
The patent applies local quality by introducing ceramic particles specifically at the interfaces between carbon fibers and the carbon matrix, rather than uniformly throughout the material. This localized introduction targets the wear-prone regions while minimizing carbon consumption from the reinforcement fibers, thereby improving wear resistance without significantly degrading mechanical properties.
Solution Approach 2:
The patent utilizes the porous structure of the carbon matrix to introduce ceramic particles. The pores in the carbon matrix serve as repositories for the ceramic particles, allowing them to be embedded at the fiber-matrix interfaces without requiring additional carbon consumption from the reinforcement fibers. This approach enables wear protection while preserving the structural integrity of the carbon fibers.
2Reliability
If impregnation with sol-gel type solution containing ceramic precursor is carried out, then ceramic particles are dispersed in the preform, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by performing the impregnation with sol-gel type solution containing ceramic precursor before the final densification of the preform. This timing allows the ceramic particles to be introduced and dispersed throughout the carbon matrix while the preform structure is still accessible, facilitating uniform distribution without requiring complex post-processing steps.
Solution Approach 2:
The patent uses the sol-gel type solution as an intermediary medium to introduce ceramic particles into the preform. The sol-gel solution acts as a carrier that delivers the ceramic precursor uniformly throughout the preform structure, and upon drying and heat treatment, leaves behind evenly dispersed ceramic particles without requiring complex mixing or handling equipment.
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
Significantly reduces friction wear at low temperatures while avoiding carbon consumption from the fibers, enhancing the mechanical properties and efficiency of the composite material.
Implementation Method 1
impregnation of a sol-gel type solution with ceramic compound precursors, followed by heat treatment to achieve dispersion of particles
Implementation Method 2
heat treatment to achieve dispersion of particles with reduced average size (less than 250 nm) within the composite material
Implementation Method 3
the precursor vaporized in contact with the preform diffuses within it to form a PyC deposit by decomposition
Implementation Method 4
the gas phase to diffuse within the preforms and to form a solid deposit of pyrolytic carbon (PyC) by decomposition of the precursor(s)
Data Source
Figure 1~3
Figure 4~5
AI summary
A fibrous preform made from carbon fibres is densified with a carbon matrix in multiple separate cycles. After a first densification cycle, and prior to the end of the densification with the carbon matrix, ceramic particles are introduced in order to be dispersed inside the part made from composite material. The particles introduced have an average size of less than 250 nm and are made from at least one ceramic compound of an element selected from titanium, yttrium, tantalum and hafnium, said ceramic compound being selected from oxides, nitrides and mixed oxide, carbide and/or nitride compounds which do not react with carbon at a temperature below 1000?C and which have a melting point above 1800?C.