Carbon-Carbon Brake Disk Micro-Crack Sealing by Final CVD
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Solution Overview
Problem
The manufacturing process of carbon/carbon brake disks often results in micro-cracks due to final heat treatment, which allows moisture and oxidation protection systems to penetrate, leading to reduced friction performance and wear life.
Innovation Solution
A method involving the formation of a fibrous network from oxidized carbon fibers, carbonization, infiltration with carbon using CVI/CVD processing, and a final chemical vapor deposition (CVD) process at 1000°C to fill micro-cracks and prevent penetration of oxygen, moisture, and oxidation protection systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If final heat treatment (FHT) process is performed at high temperature (1400-2200°C), then mechanical strength and friction performance are improved, but micro-cracks are generated in the C/C part
Solution Approach 1:
The patent performs a preliminary action by conducting a final chemical vapor deposition (CVD) process at approximately 1000°C after the high-temperature FHT process. This secondary CVD process deposits carbon material that fills the micro-cracks generated during FHT, sealing them before the brake disk enters service. The low-temperature CVD treatment is applied in advance to prevent harmful effects of micro-cracks while maintaining the mechanical strength benefits of high-temperature FHT.
2Productivity
If micro-cracks are present in the C/C part, then manufacturing complexity is reduced, but penetration of oxygen, moisture, and OPS chemicals occurs leading to reduced wear life
Solution Approach 1:
The patent converts the harmful effect of micro-cracks into a beneficial process by utilizing them as pathways for carbon deposition. During the final CVD process at 1000°C, carbon material deposits preferentially into the micro-cracks, filling them and transforming these defects into sealed, structurally sound regions. This approach maintains manufacturing efficiency while eliminating the reliability issues caused by micro-crack penetration of oxygen, moisture, and OPS chemicals.
3Manufacturing precision
If final CVD process is performed for extended duration (20-100 hours), then micro-crack filling and seal quality are improved, but manufacturing time and energy consumption increase
Solution Approach 1:
The patent optimizes the balance between micro-crack filling quality and processing time by carefully controlling CVD parameters including temperature (approximately 1000°C), pressure, carbon source gas composition, and deposition time (20-100 hours). By adjusting these parameters, the process achieves adequate micro-crack sealing without requiring excessively long processing times, thereby reducing energy consumption and manufacturing cycle time while maintaining sufficient seal quality.
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 method increases the wear life of carbon/carbon brake disks by sealing micro-cracks and preventing inhibitors from reaching the wear surface, thereby maintaining friction performance and mechanical strength.
Implementation Method 1
performing a final chemical vapor deposition (CVD) process at approximately 1000° C. to at least partially fill in a micro-crack in the C/C part
Implementation Method 2
carbonizing the oxidized carbon fiber precursor by heating the oxidized carbon fiber precursor at 1400-2800° C. to form a carbon fiber
Data Source
AI summary
A carbon/carbon brake disk is provided. The carbon/carbon brake disk may comprise a carbon fiber, wherein the carbon fiber is formed into a fibrous network, wherein the fibrous network comprises carbon deposited therein. The carbon fiber may undergo a FHT process, wherein micro-cracks are disposed in the carbon fiber. In various embodiments, the micro-cracks may be at least partially filled with un-heat-treated carbon via a final CVD process, wherein the final CVD process is performed at a temperature in the range of up to about 1,000° C. (1,832° F.) for a duration in the range from about 20 hours to about 100 hours. In various embodiments, the un-heat-treated carbon may be configured to prevent oxygen, moisture, and/or oxidation protection systems (OPS) chemicals from penetrating the carbon/carbon brake disk. In various embodiments, the final CVI/CVD process may be configured to increase the wear life of the carbon/carbon brake disk.