SiO2 Barrier Coating with Self-Sealing Microcracks
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Solution Overview
Problem
Gas turbine engine components face challenges in thermal and oxidative stability due to high temperatures, corrosive, and oxidative conditions, which existing protective barrier coatings are unable to effectively address.
Innovation Solution
A ceramic-based substrate with a barrier layer comprising a matrix of SiO2 and a dispersion of silicon oxycarbide particles, along with barium-magnesium alumino-silicate particles, which provides enhanced oxidation and moisture protection by forming a sealing layer and diffusing to seal microcracks, thereby improving the thermal and oxidative stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective barrier coating is applied to improve thermal and oxidative stability, then the component can withstand high temperatures and corrosive conditions, but the coating may develop microcracks under thermal stress which reduces protection effectiveness
Solution Approach 1:
The patent modifies the chemical composition parameters of the barrier coating by incorporating reactive particles (silicon carbide, silicon oxycarbide, and barium-magnesium alumino-silicate) into the SiO2 matrix. These compositional changes enable the coating to dynamically respond to thermal stress by forming sealing products that repair microcracks, thus maintaining coating integrity while withstanding high temperatures and oxidative conditions.
2Object-affected harmful factors
If existing barrier coatings are used under high temperature conditions, then they provide some protection, but they fail to effectively seal microcracks which leads to reduced oxidation resistance over time
Solution Approach 1:
The barrier coating incorporates reactive particles (silicon carbide, silicon oxycarbide, and barium-magnesium alumino-silicate) that automatically react with oxygen to form sealing products (silicon dioxide and barium-magnesium alumino-silicate) when microcracks form. This self-healing mechanism continuously seals cracks without external intervention, maintaining oxidation resistance throughout the service life of the coating.
Solution Approach 2:
The patent converts the harmful effect of oxygen (which causes oxidation and microcrack propagation) into a beneficial sealing mechanism. When microcracks form and expose reactive particles to oxygen, the oxygen reacts with these particles to form sealing products that close the cracks, thus transforming the harmful oxidative environment into a self-healing mechanism that extends protection duration.
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 composite barrier layer effectively protects the underlying substrate from oxygen and moisture, enhancing its oxidation resistance and maintaining stability at high temperatures for extended periods, such as 2000-2700°F for 500 hours or longer.
Implementation Method 1
a dispersion of barium-magnesium alumino-silicate particles in the matrix. The barium-magnesium alumino-silicate particles have an average maximum dimension that is between about 10-40% of an average maximum dimension of the silicon oxycarbide particles
Implementation Method 2
The silicon oxycarbide particles have Si, O, and C in a covalently bonded network
Implementation Method 3
maintaining stability at high temperatures for extended periods, such as 2000-2700°F for 500 hours or longer
Data Source
AI summary
An article includes a ceramic-based substrate and a barrier layer on the ceramic-based substrate. The barrier layer includes a matrix of SiO2 and a dispersion of silicon oxycarbide particles in the matrix. The silicon oxycarbide particles have Si, O, and C in a covalently bonded network, and a dispersion of barium-magnesium alumino-silicate particles in the matrix. The barium-magnesium alumino-silicate particles have an average maximum dimension that is between about 10-40% of an average maximum dimension of the silicon oxycarbide particles. A composite material and a method of applying a barrier layer to a substrate are also disclosed.