Multi-Layer Coating for C/C Brake Disks Under Oxidation and Wear
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Solution Overview
Problem
Aircraft carbon brake friction disks face challenges with oxidation protection and wear improvement, as existing technologies do not effectively address the degradation of carbon/carbon (C/C) disks under high frictional loads and exposure to environmental factors.
Innovation Solution
A method involving the application of multiple coatings to densified C/C friction disks, including a first coating of boron carbide powder, surfactants, and a carrier fluid on non-wear surfaces, and a second coating of aluminum, silicon, a solvent, and a carrier fluid on both non-wear and wear surfaces, along with additional coatings of aluminum oxide, phosphoric acid derivatives, and glass compositions to enhance oxidation protection and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple coatings are applied to C/C friction disks, then oxidation protection and wear resistance are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The coating system is divided into multiple functional layers: a first coating containing boron carbide powder applied to non-wear surfaces, and a second coating containing aluminum and silicon applied to wear surfaces. Each layer performs a specific protective function, allowing the system to achieve comprehensive protection while maintaining manageable complexity through functional segmentation.
Solution Approach 2:
Different coating compositions are applied to different surfaces of the C/C friction disk based on their specific functional requirements. Non-wear surfaces receive a coating optimized for oxidation resistance, while wear surfaces receive a coating optimized for both oxidation resistance and wear protection. This local differentiation maximizes protection effectiveness without uniformly increasing complexity across the entire component.
2Duration of action of moving object
If multiple coatings are applied to C/C friction disks, then wear resistance is improved, but manufacturing time and process complexity increase
Solution Approach 1:
The coating materials are pre-mixed with appropriate carriers and applied in predetermined sequences before the C/C friction disk enters service. The first coating is applied to non-wear surfaces and the second coating to wear surfaces in advance, ensuring that the protective layers are established before operational wear begins. This preliminary application prevents wear damage from the outset, extending service life without requiring complex in-service maintenance.
Solution Approach 2:
The coating system uses composite material formulations: the first coating combines boron carbide powder with carrier materials, and the second coating combines aluminum and silicon with carrier materials. These composite coatings provide multiple protective functions (oxidation resistance, wear resistance) in single applied layers, reducing the number of separate manufacturing steps needed compared to applying multiple thin layers of single-function materials.
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 multi-coating approach significantly enhances the oxidation protection and wear improvement of C/C friction disks, leading to increased landings per overhaul (LPO) and reduced oxidation fallout during maintenance, thereby extending the operational life of aircraft carbon brakes.
Implementation Method 1
a first coating is applied to a radially inward non-wear surface and a radially outward non-wear surface of the densified C/C friction disk... the first coating is a mixture including boron carbide (B4C) powder
Implementation Method 2
a second coating is applied to the radially inward non-wear surface, the radially outward non-wear surface, and the wear surfaces of the densified C/C friction disk... the second coating is a mixture including aluminum (Al), silicon (Si)
Implementation Method 3
a third coating is applied to the radially inward non-wear surface and the radially outward non-wear surface of the densified C/C friction disk... the third coating is a mixture of aluminum oxide (Al2O3)
Implementation Method 4
a fourth coating is applied to the radially inward non-wear surface and the radially outward non-wear surface of the densified C/C friction disk... the fourth coating is a mixture of at least one of a phosphoric acid, an aluminum phosphate
Implementation Method 5
a fifth coating is applied to the radially inward non-wear surface and the radially outward non-wear surface of the densified C/C friction disk... the fifth coating is a mixture that includes a glass composition in glass frit or powder form
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
A method is provided for providing oxidation protection and wear improvement for a densified carbon/carbon (C/C) friction disk. The method includes applying a first coating to a radially inward non-wear surface (404) and a radially outward non-wear surface (406) of the densified C/C friction disk and applying a second coating (414) to the radially inward non-wear surface (404), the radially outward non-wear surface (406), and the wear surfaces of the densified C/C friction disk.