Boron-Silicon Glass Coating for Hydrolysis-Resistant Composites
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Solution Overview
Problem
Oxidation protection systems for carbon-carbon composite structures face hydrolytic instability due to the formation of water-soluble diboron trioxide at high temperatures, leading to material loss and degradation.
Innovation Solution
A method involving the application of boron and silicon slurries, each containing glass compounds and glass formers, along with carrier fluids, to form a boron-glass and silicon-glass layer on carbon-carbon composite structures, which includes a pretreatment composition to enhance stability and self-healing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation protection systems use layers of boron carbide and silicon carbide to reduce oxygen infiltration, then oxidation protection is improved, but hydrolytic stability deteriorates due to water-soluble diboron trioxide formation
Solution Approach 1:
The patent introduces an intermediary substance (glass former such as borosilicate glass) that mediates between the boron carbide layer and the environment. This glass former forms a protective barrier that prevents water from reaching and dissolving the diboron trioxide, while still allowing the oxidation protection function to operate. The intermediary resolves the contradiction by providing a shielding layer that blocks the harmful water-boron trioxide interaction.
Solution Approach 2:
The patent creates a composite protection system combining multiple materials: boron carbide for oxidation resistance, silicon carbide for structural stability, and glass former compounds for hydrolytic stability. This multi-material composite approach allows each component to address specific weaknesses, with the glass former component specifically preventing water dissolution while the boron and silicon carbide layers provide oxidation protection.
2Stability of the object's composition
If glass formers are added to boron and silicon slurries to improve water stability, then hydrolytic stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into a single slurry application process. The slurry combines boron or silicon compounds with glass formers in one mixture that can be applied simultaneously, rather than requiring separate application steps for different protective layers. This integration reduces manufacturing complexity while achieving the desired water stability through the combined action of the compounds.
Solution Approach 2:
The patent modifies the chemical composition parameters of the slurry by incorporating specific glass formers (such as borosilicate glass with specific oxide ratios) that change the physical and chemical properties of the protective layer. By adjusting these compositional parameters, the system achieves enhanced water stability without fundamentally changing the manufacturing process, thus limiting the increase in complexity.
3Temperature
If oxidation protection systems are designed for high temperature operation, then temperature resistance is improved, but material loss increases due to diboron trioxide formation and dissolution
Solution Approach 1:
The patent converts the harmful effect of diboron trioxide formation at high temperatures into a beneficial protective mechanism. Instead of preventing diboron trioxide formation, the system allows it to form and then uses the glass former to create a sealed protective layer around it, preventing water from dissolving it. This approach transforms what was previously a source of material loss into a stable, protected component of the protection system.
Solution Approach 2:
The patent applies the glass former-containing slurry beforehand to create a protective cushion or barrier layer that will prevent water from reaching the diboron trioxide formed during high-temperature operation. This prior cushioning approach ensures that when the boron carbide converts to diboron trioxide at operating temperatures, the material is already protected from water dissolution, preventing subsequent material loss.
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 solution significantly reduces material loss by forming a stable boron-silicon oxidation protection system that increases water stability and extends the temperature range of protection, effectively preventing oxidation and hydrolysis.
Implementation Method 1
each of the first glass former and the second glass former may comprise colloidal silica
Implementation Method 2
The boron-glass layer may comprise a boron compound, a first glass compound, and a first glass former. The silicon-glass layer may comprise a silicon compound, a second glass compound, and a second glass former.
Implementation Method 3
Oxidation protection systems for carbon-carbon composites are typically designed to minimize loss of carbon material due to oxidation at high temperature operating conditions
Implementation Method 4
heating the carbon-carbon composite structure
Implementation Method 5
The method may further comprise drying the brake disk after applying the boron slurry to remove the first carrier fluid
Data Source
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AI summary
Systems and methods for forming an oxidation protection system on a composite structure are provided. In various embodiments, the oxidation protection system comprises a boron-glass layer formed on the composite substrate and a silicon-glass layer formed over the boron-glass layer. Each of the boron-glass layer and the silicon-glass layer includes a glass former.