Interlocking Silica Coating for Creep Resistance
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Solution Overview
Problem
High-temperature turbine engine components with silicon-containing materials face degradation due to creep displacement under shear loading, as the thermally grown amorphous silica layer exhibits high creep rates, leading to severe damage and loss of protective barrier functionality.
Innovation Solution
An environmental barrier coating system is developed with engineered surface features such as channels and ridges on the silicon-containing region, which interlock with the initial coating layer to inhibit creep displacement, enhancing the structural integrity and protective capabilities of the coating system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coating system is applied to silicon-containing materials in high-temperature turbine engine components, then environmental protection is improved by inhibiting the formation of volatile silicon hydroxide products, but creep displacement occurs under shear loading due to the high creep rate of the thermally grown amorphous silica layer
Solution Approach 1:
Surface features (channels and ridges) are formed on the silicon-containing region before applying the environmental barrier coating. This preliminary action creates an interlocking geometry that prevents creep displacement of the coating system under high-temperature shear loading, while still allowing the silica layer to form its protective barrier function.
Solution Approach 2:
The surface of the silicon-containing region is segmented into ridges and channels, creating a textured topography that interlocks with the environmental barrier coating. This segmentation provides mechanical anchoring points that resist creep displacement while maintaining the coating's environmental protection capabilities.
2Reliability
If the amorphous silica layer is allowed to form on the silicon-containing bondcoat, then low oxygen permeability is achieved providing environmental protection, but high creep rate under shear loading causes creep displacements and severe EBC damage
Solution Approach 1:
Surface features are created on the silicon-containing region before the silica layer forms during thermal processing. The ridges and channels are established in advance, and as the silica layer thermally grows on the bondcoat, it conforms to this pre-established geometry, creating an interlocked structure that maintains both environmental protection and structural stability.
Solution Approach 2:
The system combines the amorphous silica layer (providing environmental protection through low oxygen permeability) with the engineered surface features (channels and ridges) to create a composite structure. This composite approach allows the silica to fulfill its protective function while the surface geometry provides creep resistance, resolving the contradiction between environmental protection and structural stability.
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 interlocking surface features significantly reduce creep displacements, ensuring the structural integrity and protective efficacy of the environmental barrier coating system, even under high shear loads and elevated temperatures.
Implementation Method 1
The silicon content of a silicon-containing bondcoat reacts with oxygen at high temperatures to form predominantly an amorphous silica (SiO2) scale
Implementation Method 2
The amorphous silica product exhibits low oxygen permeability. As a result, along with the silicon-containing bondcoat, the silica product that thermally grows on the bondcoat is able to form a protective barrier layer
Data Source
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Figure 3~3B
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AI summary
A method of forming an article includes forming a silicon-containing layer on a silicon-containing region of a surface of a substrate of the article; forming a plurality of channels and ridges in the silicon-containing layer; and forming at least one outer layer overlying the surface of the silicon-containing region. The plurality of channels and ridges may be formed by adding silicon-containing material to the silicon-containing layer. The channels and ridges may be formed by subtracting material from the silicon-containing layer. The channels and ridges may be formed by forming channels or grooves in the silicon-containing region of the surface of the substrate prior to formation of the silicon-containing layer.