High-Temperature Barrier Coating for Oxidation-Resistant C/C Components
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Solution Overview
Problem
High-temperature carbon, carbon-carbon (C/C) composite, and ceramic components used in aerospace and other applications are susceptible to oxidation, leading to deterioration of mechanical properties and reduced useful life, especially during exposure to high temperatures and catalytic substances.
Innovation Solution
A barrier coat formulation comprising mono-aluminum phosphate, boron carbide, and tungsten or tungsten compounds is applied to the components, followed by heat treatment to form an oxidation-resistant coating layer with a melting point greater than 800°C, providing protection against oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon, C/C composite, or ceramic materials are used in high temperature applications, then good mechanical properties and low mass density are achieved, but susceptibility to oxidation occurs leading to deterioration of physio-mechanical properties
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of a penetrant antioxidant underlayer and an antioxidant topcoat. This composite structure combines different materials with complementary functions: the underlayer provides penetration and adhesion to the substrate, while the topcoat provides the primary oxidation barrier. This resolves the contradiction by creating a protective composite system that maintains the inherent mechanical advantages of carbon-based materials while adding oxidation resistance through material composition design.
Solution Approach 2:
The coating system applies different materials and properties to different layers: the penetrant underlayer has different characteristics (designed to infiltrate and bond with substrate) than the antioxidant topcoat (designed to resist oxidation). This local differentiation of material properties allows each layer to optimize its specific function, resolving the contradiction between maintaining substrate mechanical properties and providing oxidation protection.
2Reliability
If conventional antioxidant coatings are applied to protect against oxidation, then oxidation resistance is improved, but the coatings may decompose over repeated exposure to high temperatures
Solution Approach 1:
The penetrant antioxidant underlayer is applied first to create a protective foundation before the topcoat is applied. This underlayer penetrates the substrate surface and provides initial oxidation protection and adhesion, cushioning against the harsh high-temperature environment before the topcoat is exposed. This sequential protective strategy allows the coating system to withstand repeated thermal cycling without decomposition, extending service life while maintaining oxidation resistance.
Solution Approach 2:
The two-layer composite coating structure distributes the thermal and oxidative stress across different materials with complementary high-temperature stability. The penetrant underlayer and antioxidant topcoat are both formulated to withstand high temperatures, and their composite structure prevents decomposition by ensuring neither layer is overloaded beyond its thermal tolerance. This resolves the contradiction by creating a thermally stable protective system.
3Reliability
If a barrier coating is applied to protect against oxidation, then oxidation resistance is improved, but the coating formulation must withstand extreme temperatures without decomposing
Solution Approach 1:
The coating formulation uses specific materials selected for their high thermal stability parameters. The penetrant underlayer and antioxidant topcoat are both formulated with materials that maintain structural integrity at temperatures exceeding 1000°C. By carefully selecting and optimizing the thermal parameters of the coating materials, the system achieves both oxidation resistance and thermal stability, resolving the contradiction between protective function and temperature withstand 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 resulting oxidation-resistant coating layer effectively protects the components from high-temperature oxidation, maintaining mechanical integrity and extending their useful life even at extreme temperatures.
Implementation Method 1
heat treating the barrier coat formulation to form an oxidation-resistant coating layer
Implementation Method 2
The oxidation-resistant coating layer has a melting point of greater than about 800 degrees Celsius (°C)
Data Source
Figure 1~2
Figure 3
AI summary
In examples, a method for forming a high temperature coating includes applying a barrier coat formulation on a substrate. The barrier coat formulation includes mono-aluminum phosphate; boron carbide; and tungsten. The method further includes heat treating the barrier coat formulation to form an oxidation-resistant coating layer, wherein a melting point of the oxidation-resistant coating layer is greater than about 800 degrees Celsius (°C).