Silicon Boria Stabilizing Bond Layer for CMC Coating Delamination
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Solution Overview
Problem
Ceramic matrix composite (CMC) components in high-temperature mechanical systems, such as gas turbine engines, face degradation due to reactions with environmental elements and compounds, leading to reduced lifespan, despite the use of environmental barrier coatings, as boria present in the substrate can migrate and interact with silica scales, causing delamination and spallation.
Innovation Solution
A coating system for CMC substrates that includes a bond layer with silicon metal and a boria stabilizing agent, such as zinc silicate, which forms a stabilized boron complex that inhibits boria migration and reduces the viscosity of silica scales, thereby enhancing the thermal compatibility and durability of the coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an environmental barrier coating is applied to protect the ceramic or CMC substrate from environmental elements, then the substrate is protected from degradation, but boria present in the substrate migrates and interacts with silica scales causing delamination and spallation
Solution Approach 1:
A bond layer comprising silicon and boria stabilizing agent is introduced as an intermediary between the ceramic/CMC substrate and the environmental barrier coating. This bond layer prevents direct harmful interaction between migrating boria and silica scales, while maintaining coating adhesion through controlled chemical composition and thermal expansion properties
Solution Approach 2:
The bond layer modifies the chemical composition parameters by incorporating silicon and boria stabilizing agent in specific ratios. This changes the thermal and chemical properties of the interface region, creating a stable transition zone that prevents delamination while allowing controlled boria migration
2Stability of the object's composition
If a bond layer with silicon and boria stabilizing agent is used to prevent boria migration, then coating adhesion is improved, but the device complexity increases
Solution Approach 1:
The coating system is segmented into distinct functional layers: the bond layer (silicon + boria stabilizing agent) and the environmental barrier coating. This segmentation allows each layer to be optimized for its specific function while maintaining overall system simplicity through clear interface definitions
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 proposed coating system improves the adherence and durability of the ceramic or CMC substrates by forming a stabilized boron complex that prevents boria migration and reduces crystallization of silica scales, leading to increased service life and reduced mechanical stress in high-temperature environments.
Implementation Method 1
forming a stabilized boron complex that inhibits boria migration
Implementation Method 2
reduces the viscosity of silica scales
Implementation Method 3
reduces crystallization of silica scales
Implementation Method 4
a bond layer on the substrate that includes silicon metal and a boria stabilizing agent
Data Source
Figure 1~2
Figure 3
AI summary
An article having a substrate that includes a ceramic or a ceramic matrix composite, a bond layer on the substrate that includes silicon metal and a boria stabilizing agent, and at least one additional layer on the bond layer.