Carbon-Carbon Oxidation Coating for Broad Temperature Protection
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Solution Overview
Problem
Carbon-carbon composite structures are prone to oxidation at high temperatures, leading to material loss and degradation, with existing coatings having limited temperature ranges of effectiveness.
Innovation Solution
A boron and silicon-based oxidation protection system (OPS) is applied to carbon-carbon composites, comprising multiple glass compounds with varying viscosity-temperature profiles to form a multi-layer coating that seals cracks and removes oxygen, providing broad temperature protection from 800°F to 1800°F.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single ceramic coating is applied to protect carbon-carbon composites, then oxidation protection is effective within a specific temperature range, but the coating degrades quickly when the temperature exceeds its optimal range
Solution Approach 1:
The coating system is divided into multiple discrete layers, each with specific functionality. The barrier layer (silicon carbide or silicon oxide) provides oxidation resistance, while the glass matrix layer (containing phosphate glass and borosilicate glass) provides sealing and adhesion. This segmentation allows each layer to be optimized for its specific function, enabling the composite coating to protect across a broader temperature range than a single coating could achieve alone.
Solution Approach 2:
The invention uses a composite coating structure combining ceramic materials (silicon carbide, silicon oxide) with a glass matrix (phosphate glass and borosilicate glass). This composite approach leverages the high-temperature stability of ceramics and the sealing/adhesion properties of glass, creating a coating system that maintains protection effectiveness across temperatures from 800°F to 1800°F, overcoming the limited temperature range of single-material coatings.
2Object-affected harmful factors
If ceramic coatings are used to protect carbon-carbon composites from oxidation, then protection is provided at high temperatures, but the coatings are brittle and have limited operating temperature ranges
Solution Approach 1:
The glass composition parameters are specifically adjusted to achieve optimal performance. The glass matrix contains phosphate glass (20-40 wt%) and borosilicate glass (60-80 wt%) with controlled viscosity-temperature profiles. This parameter optimization allows the glass to remain sufficiently viscous at high temperatures to maintain structural stability while being able to flow at lower temperatures to seal cracks and accommodate thermal expansion, thus preventing brittleness across the operating temperature range.
Solution Approach 2:
Different regions of the coating have different compositions and properties optimized for their specific functions and locations. The barrier layer contains high concentrations of silicon carbide or silicon oxide for oxidation resistance, while the glass matrix layer provides sealing and adhesion. This local quality differentiation allows the coating as a whole to achieve both oxidation protection and structural stability, with each layer contributing its specialized properties.
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 OPS effectively protects carbon-carbon composites across a wide temperature range, enhancing service life, reducing maintenance and production costs, and minimizing carbon footprint.
Implementation Method 1
the first glass compound having a first viscosity-temperature profile that is at least one order of magnitude below a second viscosity-temperature profile of the second glass compound
Implementation Method 2
OPS coatings protect C/C composites from oxidation damage through forming a barrier to block oxygen diffusion into the C/C substrate
Implementation Method 3
an oxygen gettering phase is incorporated in the coating structure to remove O2 molecules that diffused into the coating through fine cracks and defects
Implementation Method 4
heating the carbon-carbon composite structure
Data Source
AI summary
A method for forming an oxidation protection system on a carbon-carbon composite structure can comprise applying a boron slurry to the carbon-carbon composite structure, wherein the boron slurry comprises a boron compound, a first glass mixture, a first glass former, a first glass modifier, and a first carrier fluid, the first glass mixture including a first glass compound and a second glass compound, the first glass compound having a first viscosity-temperature profile that is at least one order of magnitude below a second viscosity-temperature profile of the second glass compound; applying a silicon slurry to the carbon-carbon composite structure, wherein the silicon slurry comprises a silicon compound, a third glass compound, a second glass former, a second glass modifier, and a second carrier fluid; and heating the carbon-carbon composite structure.