Barrier Coating Composition for High-Temperature Oxidation Protection
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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 increases 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 barrier coat. The underlayer contains phosphate-based compounds that penetrate into the substrate, while the barrier coat contains aluminum phosphate, boron carbide, and tungsten compounds. This composite structure provides both penetration protection and surface barrier functions, resolving the contradiction between maintaining mechanical properties and preventing oxidation.
Solution Approach 2:
The coating system acts as an intermediary layer between the carbon/C/C composite/ceramic substrate and the oxidizing environment. The penetrant underlayer creates a chemical barrier within the substrate pores, while the barrier coat provides a physical barrier on the surface. This intermediary protective system prevents direct contact between oxygen and the substrate, maintaining mechanical properties while protecting against oxidation.
2Reliability
If conventional antioxidant coatings are applied to protect against oxidation, then oxidation resistance is improved, but the coating may decompose over repeated exposure to high temperatures or extreme temperature exposure
Solution Approach 1:
The patent uses materials with specifically selected thermal stability parameters. The barrier coat contains aluminum phosphate (melting point >1000°C), boron carbide, and tungsten compounds, all chosen for their high temperature stability. The multi-layer structure with specific thickness ratios (underlayer 1-10 micrometers, barrier coat 10-50 micrometers) optimizes thermal resistance. These parameter selections ensure the coating maintains protection during repeated high temperature exposure and extreme temperature events.
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, wherein a melting point of the oxidation-resistant coating layer is greater than about 800° C.
Implementation Method 2
The oxidation-resistant barrier coating may protect the substrate from oxidation and the resulting loss of strength and loss of useful life, even 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 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.).