High-Temperature Barrier Coating for Oxidation-Resistant Carbon Composites
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Solution Overview
Problem
High-temperature carbon, carbon-carbon composite, and ceramic components used in aerospace and other applications are susceptible to oxidation, leading to deterioration of mechanical properties and reduced useful life.
Innovation Solution
A barrier coat formulation comprising mono-aluminum phosphate, boron carbide, and chromium 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 high-temperature 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 coating system comprising a bond coat layer and a top coat layer on carbon or C/C composite substrates. The bond coat layer contains aluminum and chromium oxides, while the top coat layer contains aluminum oxide and chromium oxide in specific proportions. This composite coating structure provides synergistic protection against oxidation at high temperatures, resolving the contradiction between high-temperature operation and oxidation resistance.
Solution Approach 2:
The coating system creates a protective barrier that effectively creates an inert environment around the carbon substrate. The aluminum oxide and chromium oxide layers prevent oxygen from reaching the carbon material, thereby protecting it from oxidation. This inert barrier approach allows the carbon component to operate at high temperatures without direct exposure to oxidizing atmosphere.
2Ease of manufacture
If conventional coating formulations are applied to carbon substrates, then the coating can be applied easily, but the coating lacks sufficient oxidation resistance at extremely high temperatures
Solution Approach 1:
The patent specifies precise compositional parameters for the coating layers: the bond coat layer contains 70-90 wt% aluminum oxide and 10-30 wt% chromium oxide, while the top coat layer contains 80-95 wt% aluminum oxide and 5-20 wt% chromium oxide. These controlled parameter changes in composition ensure optimal oxidation resistance at high temperatures while maintaining ease of application through conventional coating formulations.
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 oxidation-resistant coating layer effectively protects the substrate from oxidation at high and extremely high temperatures, maintaining the mechanical integrity and extending the useful life of the components.
Implementation Method 1
heat treating the barrier coat formulation to form an oxidation-resistant coating layer
Implementation Method 2
The oxidation-resistant coating layer effectively protects the substrate from oxidation at high and extremely high temperatures
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; boron carbide; and chromium or a chromium compound. 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.).