Composite Oxidation Coating With Borosilicate Crack Sealing
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Solution Overview
Problem
Carbon-carbon composite structures in high-temperature applications, such as aircraft braking systems, face significant oxidation issues due to infiltration of oxygen and catalytic contaminants, leading to material loss and degradation, especially at non-wear surface edges where phosphate glass-based oxidation protection systems may migrate and crack, exposing the composite to further oxidation.
Innovation Solution
A method involving the application of a boron slurry followed by a silicon slurry, with subsequent heating to form boron and silicon layers, and the application of sealing slurries comprising monoaluminum phosphate and phosphoric acid to create a robust oxidation protection system that prevents migration and self-heals cracks, using boron and silicon compounds like titanium diboride, boron nitride, and silicon carbide, respectively, to form a borosilicate glass that maintains viscosity and integrity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphate glass-based oxidation protection systems are applied to non-wear surfaces of brake disks, then oxidation protection is provided, but the OPS may migrate away from non-wear surface edges at high temperatures, leaving the composite material vulnerable to oxidation
Solution Approach 1:
The patent modifies the chemical composition parameters of the oxidation protection system by incorporating boron compounds (such as boron carbide, boron nitride, or boron oxide) in addition to phosphate glass. This compositional parameter change increases the viscosity of the protection system at high temperatures, preventing migration while maintaining oxidation protection capabilities.
Solution Approach 2:
The invention creates a composite oxidation protection system combining phosphate glass with boron-containing compounds. This composite material leverages the oxidation resistance of phosphate glass while the boron component provides high-temperature viscosity stability, preventing edge migration and enhancing overall reliability.
2Object-affected harmful factors
If phosphate-based oxidation protection systems are used, then infiltration of oxygen and oxidation catalysts is reduced, but significant oxidation of carbon-carbon composites still occurs during operation
Solution Approach 1:
The patent applies different materials to different regions of the brake disk surface. Boron-containing compounds are specifically applied to non-wear surfaces and edges where oxidation protection is most critical, while wear surfaces maintain their friction characteristics. This localized quality enhancement provides targeted oxidation resistance where needed most.
Solution Approach 2:
The composite oxidation protection system combines phosphate glass for oxygen infiltration reduction with boron compounds for enhanced oxidation resistance. The synergistic interaction between these materials provides superior protection against both oxygen infiltration and catalytic oxidation, significantly improving reliability.
3Duration of action of stationary object
If oxidation protection systems are applied to prevent material loss, then durability is improved, but cracks in the OPS expose the composite to oxidation
Solution Approach 1:
The boron-containing oxidation protection system exhibits self-healing capabilities. When cracks form, the boron compounds react with oxygen to form boron oxide, which fills and seals the cracks, preventing further oxidation. This self-service mechanism maintains reliability even after crack formation, extending the duration of protective action.
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 described method effectively prevents material loss by maintaining the oxidation protection system's integrity and self-healing properties, reducing oxidation and material degradation at high temperatures, and minimizing migration away from wear surfaces, thus enhancing the durability of carbon-carbon composite structures.
Implementation Method 1
heating the composite structure to a temperature sufficient to form a boron layer on the composite structure
Implementation Method 2
heating the composite structure to a temperature sufficient to form a silicon layer on the composite structure
Implementation Method 3
Phosphate-based oxidation protection systems may reduce infiltration of oxygen and oxidation catalysts into the composite structure
Implementation Method 4
boron and silicon compounds like titanium diboride, boron nitride, and silicon carbide, respectively, to form a borosilicate glass that maintains viscosity and integrity at high temperatures
Implementation Method 5
self-heals cracks, using boron and silicon compounds like titanium diboride, boron nitride, and silicon carbide, respectively, to form a borosilicate glass
Data Source
AI summary
An oxidation protection system disposed on a substrate is provided, which may comprise a boron layer comprising a boron compound disposed on the substrate; a silicon layer comprising a silicon compound disposed on the boron layer; and at least one sealing layer comprising monoaluminum phosphate and phosphoric acid disposed on the silicon layer.