Sol-Gel Silicon Oxide Coating for Carbon Fiber Oxidation Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Carbon-carbon composite structures, such as those used in aircraft braking systems, experience significant oxidation despite existing oxidation protection systems, leading to material loss and structural weakening due to high operating temperatures and infiltration of oxygen and contaminants.
Innovation Solution
A method involving the application of a slurry comprising tetraethylorthosilicate (TEOS) onto carbon fibers, followed by heating to form a silicon oxide protective layer, which is then condensed to prevent oxidation, is applied to the carbon fibers during the manufacturing process of composite structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphate-based oxidation protection systems are applied to carbon-carbon composites, then infiltration of oxygen and oxidation catalysts is reduced, but significant oxidation still occurs during operation at high temperatures
Solution Approach 1:
The patent changes the chemical composition parameters of the protective coating from phosphate-based to silane-based (TEOS) coating. This parameter change transforms the coating chemistry to form a more effective silicon oxide barrier that better resists oxidation at high temperatures, directly addressing the insufficient protection effectiveness of phosphate-based systems.
Solution Approach 2:
The patent creates a composite protective system by applying a silane-based coating that forms a silicon oxide layer on the carbon fiber surface. This composite approach combines the carbon fiber substrate with a silicon oxide protective layer, creating a multi-material structure that provides superior oxidation resistance compared to single-material phosphate coatings.
2Loss of substance
If a protective coating is applied to prevent oxidation, then material loss and structural degradation are reduced, but the coating process adds manufacturing complexity
Solution Approach 1:
The patent employs a spray application method to deposit the TEOS slurry coating onto the carbon fiber preform. This pneumatic/hydraulic application technique allows for efficient, uniform coating coverage with minimal manual intervention, reducing the practical manufacturing complexity despite the additional protective step.
Solution Approach 2:
The patent utilizes phase transitions in the coating process: the TEOS slurry is applied in liquid form, then heated to undergo condensation and hydrolysis reactions that transform it into a solid silicon oxide protective layer. This phase transition approach enables automatic coating formation through thermal processing, simplifying the overall manufacturing process.
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 silicon oxide protective layer effectively reduces oxidation of carbon fibers, enhancing the durability and longevity of carbon-carbon composite structures by preventing material loss and structural degradation under high-temperature operating conditions.
Implementation Method 1
heating the slurry to a temperature sufficient to form a protective layer on the carbon fiber, and condensing the slurry into a silicon oxide
Implementation Method 2
Phosphate-based oxidation protection systems may reduce infiltration of oxygen and oxidation catalysts into the composite structure
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A method for coating a carbon fiber for a composite structure may comprise applying a slurry onto a surface of the carbon fiber, wherein the slurry is a sol gel comprising a metal precursor and a carrier fluid, and heating the carbon fiber to a temperature sufficient to form a sol gel-derived layer on the carbon fiber. The slurry may comprise a metal precursor such as a metal salt or a metal alkoxide. The sol gel-derived layer may help prevent the carbon fiber from oxidizing. The metal precursor comprises at least one of aluminum nitrate, calcium nitrate, aluminum isopropoxide, aluminum sec-butoxide, aluminum oxide, tetraethylorthosilicate (TEOS), zirconium n-propoxide, and titanium isopropoxide.