Silicon Bond Coating Contained Between Refractory Layers
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Solution Overview
Problem
Silicon bond coatings used in environmental barrier coatings for ceramic components in gas turbine engines have a low melting point, limiting the operational temperature due to delamination issues at high temperatures, which leads to oxidation of the substrate and blistering from trapped gases.
Innovation Solution
A silicon-based bond coating is formed with a silicon-phase contained within a refractory phase, where the silicon-phase melts and remains contained, providing structural integrity and oxygen gettering without gas release, and is protected by refractory layers to prevent delamination and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon bond coating is used to prevent substrate oxidation and blistering, then the substrate is protected from oxidation and gas blistering, but the operational temperature is limited to below silicon's melting point due to delamination
Solution Approach 1:
The patent applies composite materials by creating a bond coating that combines silicon phase with a refractory matrix material. This composite structure allows the coating to maintain its protective function while withstanding higher temperatures, as the refractory matrix provides structural stability above silicon's melting point and prevents delamination. The composite nature enables the coating to operate reliably at temperatures exceeding 1414°C without losing adhesion to the substrate.
2Productivity
If the operational temperature is increased above silicon's melting point to improve engine efficiency, then engine efficiency improves, but the silicon bond coating delaminates and loses protective function
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the bond coating through composition adjustment. By incorporating refractory matrix materials with high melting points and appropriate thermal expansion coefficients, the coating's thermal stability parameter is changed. This allows the coating to maintain adhesion and protective function at elevated temperatures, enabling the engine to operate at higher temperatures for improved efficiency without sacrificing coating reliability.
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 solution allows for operation above the melting point of silicon, preventing substrate oxidation and blistering, thereby increasing the operational temperature limit of the environmental barrier coating system.
Implementation Method 1
the silicon-phase is contained within a refractory phase such that, when melted, the silicon-phase is contained within the refractory phase
Implementation Method 2
The silicon bond coating provides a layer that oxidizes (forming a passive silicon oxide layer beneath the EBC) without liberating a gaseous by-product
Implementation Method 3
the silicon-phase is contained within the refractory phase and between the surface of the substrate and an inner surface of the environmental barrier coating
Data Source
AI summary
A coated component, along with methods of its formation and use, is provided. The coated component may include a substrate having a surface, a first refractory layer on the surface of the substrate, a silicon-based bond coating on the first refractory layer, and an environmental barrier coating on the silicon-based bond coating. The silicon-based bond coating includes a silicon-phase contained within a refractory phase such that, when melted, the silicon-phase is contained within the refractory phase and between the surface of the substrate and an inner surface of the environmental barrier coating.