High-Temperature Barrier Coating for Oxidation-Resistant C/C Composites
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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, group four, five, or six metals, boron carbide, water, and a surfactant is applied to the substrate and heat-treated 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
1Temperature
If carbon, C/C composite, or ceramic materials are used in high temperature applications, then the component can operate at high temperatures, but the component becomes susceptible to oxidation leading to deterioration of mechanical properties
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of a barrier coat layer (containing aluminum phosphate, metal powders, and boron carbide) and an antioxidant layer (containing phosphate-based antioxidants). This composite structure provides both high-temperature stability and oxidation resistance, resolving the contradiction between operating temperature and reliability.
Solution Approach 2:
The barrier coat formulation undergoes parameter changes during heat treatment, transforming from a precursor state to a sintered coating with enhanced properties. The aluminum phosphate forms a glassy matrix that binds metal particles and boron carbide, creating a coating with optimized composition and structure for high-temperature oxidation resistance.
2Reliability
If a barrier coating is applied to protect against oxidation, then oxidation resistance is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines multiple protective functions into a single integrated barrier coat formulation. The coating contains aluminum phosphate for high-temperature stability, metal powders for oxidation resistance, and boron carbide for erosion resistance, all in one application step followed by heat treatment, simplifying the manufacturing process while maintaining comprehensive protection.
Solution Approach 2:
The barrier coating formulation is designed to self-organize during heat treatment. The aluminum phosphate forms a glassy matrix that automatically binds the metal particles and boron carbide together, creating a cohesive protective layer without requiring additional processing steps or external assistance.
3Temperature
If the coating layer has high melting point for thermal stability, then high temperature resistance is improved, but the coating formulation becomes more difficult to process
Solution Approach 1:
The patent uses parameter changes to resolve the contradiction between high melting point and ease of manufacture. The coating is applied in a precursor state (slurry or paste form) at room temperature or moderate temperature, then transformed through heat treatment at high temperature to achieve the desired sintered structure with high melting point properties. This separates the application step from the property-development step.
Solution Approach 2:
The aluminum phosphate acts as an intermediary material that facilitates processing. In the applied state, it forms a workable slurry or paste that can be easily coated onto the substrate. During heat treatment, it transforms into a stable glassy matrix that provides high-temperature resistance, serving as a bridge between the easy-to-apply precursor state and the high-performance final state.
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 strength and extending the useful life by forming a durable, self-healing barrier that resists environmental degradation.
Implementation Method 1
heat treating the barrier coat formulation to form an oxidation-resistant coating layer
Implementation Method 2
oxidation-resistant coating layer... providing protection against oxidation
Data Source
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; at least one of a group four, a group five, or a group six metal or metal compound; boron carbide; water; and surfactant. 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.).