Barrier Coating Composition for High-Temperature Oxidation Resistance
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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:
A barrier coating layer is applied as an intermediary between the carbon/C/C composite/ceramic component and the oxidizing environment. The coating contains phosphates, silicates, borates, and other compounds that form a protective barrier preventing direct contact between oxygen and the substrate, thereby maintaining both high temperature operation and oxidation resistance
Solution Approach 2:
The barrier coating is formulated as a composite material containing multiple components including phosphates (e.g., ammonium polyphosphate, aluminum phosphate), silicates, borates, metal powders (aluminum, zinc, magnesium), and organic binders. This composite formulation provides synergistic protection against oxidation while maintaining thermal stability at high operating temperatures
2Reliability
If a barrier coating is applied to protect against oxidation, then oxidation resistance is improved, but the coating formulation complexity increases
Solution Approach 1:
Multiple protective functions are merged into a single barrier coating formulation that combines phosphates, silicates, borates, metal powders, and organic binders in one application layer. This unified approach provides comprehensive oxidation protection without requiring multiple separate coating layers or complex multi-step application processes
Solution Approach 2:
The coating formulation is designed to undergo controlled chemical and physical changes during heat treatment. The organic binders carbonize to form a stable matrix, while inorganic components react to form protective glassy phases and metal oxides. These parameter changes during curing transform the applied coating into a stable, oxidation-resistant barrier
3Temperature
If the barrier coating contains multiple inorganic components for high temperature stability, then the melting point is increased above 800°C, but the manufacturing process complexity increases
Solution Approach 1:
The barrier coating is formulated as a self-applied solution that can be brushed, rolled, or sprayed directly onto the component surface. The coating self-levels and adheres to the substrate, then undergoes a simple heat treatment process to cure. This self-service approach eliminates the need for complex specialized equipment or multi-step manufacturing processes while achieving high temperature stability through the inorganic composition
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 C/C composite and ceramic 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
oxidation-resistant coating layer... providing protection against oxidation
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; 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).