B4C Oxidation Coating for Carbon-Carbon Brake Disks
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Solution Overview
Problem
Phosphate-based oxidation protection systems for carbon-carbon composite brake disks in aircraft braking systems are ineffective at high temperatures, leading to oxidation and degradation, especially at non-wear surface edges, due to viscosity decrease and component evaporation.
Innovation Solution
A method of forming a boron carbide (B4C) layer on carbon-carbon composite materials using a liquid mixture of boron and carbon compounds, such as boric acid and phenolic resin, followed by heating under inert gas flow to create a durable oxidation protection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphate-based oxidation protection systems are applied to carbon-carbon composite brake disks, then oxidation protection is provided at lower temperatures, but at high operating temperatures (900°C or higher), the protection system becomes ineffective due to viscosity decrease and component evaporation
Solution Approach 1:
The patent changes the chemical composition parameters of the protection system by incorporating boron compounds (such as boron carbide B4C, boron oxide B2O3, or boron nitride BN) alongside phosphate-based compounds. This compositional parameter change enables the protection system to maintain effectiveness at high temperatures where conventional phosphate-only systems fail due to viscosity decrease and evaporation.
Solution Approach 2:
The invention creates a composite oxidation protection system that combines phosphate-based compounds with boron-containing compounds. This composite approach leverages the complementary properties of both material systems: phosphates provide protection at lower temperatures while boron compounds maintain protection at high temperatures, resolving the temperature-dependent effectiveness issue.
2Reliability
If phosphate-based oxidation protection systems are used, then oxidation protection is achieved, but at high temperatures the system migrates away from non-wear surface edges, leaving the composite material vulnerable to oxidation
Solution Approach 1:
The addition of boron compounds modifies the physical and chemical parameters of the protection system, including viscosity and thermal stability. These parameter changes prevent the migration issue observed in phosphate-only systems at high temperatures, ensuring uniform coverage is maintained across all surfaces including non-wear surface edges.
Solution Approach 2:
The boron compounds act as intermediary substances that stabilize the protection system at high temperatures. They serve as a thermal anchor that prevents the phosphate-based components from migrating away from critical areas, thereby maintaining comprehensive oxidation protection coverage.
3Reliability
If phosphate-based oxidation protection systems operate at high temperatures, then oxidation protection is attempted, but components in the OPS oxidize and evaporate, lessening the oxidation protection capabilities
Solution Approach 1:
The patent converts the potential harm of high-temperature oxidation into a benefit by using boron compounds that form stable, protective boron oxide layers when exposed to oxygen at high temperatures. Instead of the protection system components being lost to oxidation and evaporation, the boron compounds undergo controlled oxidation to create an additional protective barrier that enhances rather than diminishes oxidation protection capability.
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 B4C layer effectively prevents oxidation and degradation of carbon-carbon composite materials at high temperatures, enhancing the durability and longevity of brake components by maintaining protection against oxidation.
Implementation Method 1
heating the carbon-carbon composite material after applying the liquid mixture on the carbon-carbon composite material to from a boron carbide (B4C) layer
Implementation Method 2
heating to between about 1000 degrees Celsius and about 2000 degrees Celsius under an inert gas flow
Implementation Method 3
The B4C layer effectively prevents oxidation and degradation of carbon-carbon composite materials at high temperatures
Data Source
AI summary
A method of forming a B4C layer as a component of an oxidation protection system as component of oxidation protection system on a carbon-carbon composite material may include forming a liquid mixture comprising a boron-compound and a carbon-compound. The method may further include applying the liquid mixture on the carbon-carbon composite material. The boron compound may comprise boric acid (H3BO3). In various embodiments, the carbon-compound comprises phenolic resin. In various embodiments, the method further includes heating the carbon-carbon composite material after applying the liquid mixture on the carbon-carbon composite material to from a boron carbide (B4C) layer.