Ceramic Matrix Composite Thermal Barrier Coating Firing Sequence
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Solution Overview
Problem
Current methods for forming ceramic matrix composite components, such as gas turbine engine components, face challenges with thermal barrier coatings that experience shrinkage and sintering issues, leading to weakened bonds and limited temperature capabilities, as existing coatings must be fired at lower temperatures than the composite to prevent property loss and undesirable sintering.
Innovation Solution
A method where a ceramic layer is formed and fired before the ceramic matrix composite body, allowing higher temperature firing and preventing further sintering, with optional features including pressure application during sintering, use of particulates for enhanced bonding, and incorporation of cooling channels, and application of ceramic cement for improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal barrier coating is cast onto the ceramic matrix composite component, then thermal protection is provided, but shrinkage during drying and firing causes strain at the interfacial joint, weakening the bond and mechanical strength
Solution Approach 1:
The ceramic layer is formed and fired separately before the ceramic matrix composite body is applied and fired. This preliminary action allows the coating to be fully sintered and stabilized before bonding to the composite body, preventing shrinkage-induced strain at the interface during subsequent processing.
2Stability of the object's composition
If the coating is fired at a lower temperature than the composite, then property loss in the composite is prevented, but the firing temperature is limited and further sintering control becomes difficult
Solution Approach 1:
The coating is fired to a high temperature first to achieve full sintering and stabilize its structure. The composite body is then applied and fired at a controlled lower temperature, preventing property loss in the composite while allowing the coating to reach its optimal sintered state.
3Strength
If the coating is sintered and adhered using ceramic cement, then attachment is achieved, but the interfacial bond remains relatively weak
Solution Approach 1:
The coating is pre-sintered to achieve full densification and strength development before the composite body is applied. This eliminates the need for ceramic cement and creates a strong mechanical and chemical bond between the fully sintered coating and the composite body during the composite firing process.
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
This approach enables the formation of ceramic matrix composite components with improved thermal protection and mechanical strength, capable of withstanding higher temperatures without compromising the bond strength or structural integrity, thus enhancing the operational limits of gas turbine engines.
Implementation Method 1
firing the ceramic slurry to form a ceramic layer... the ceramic layer is fired at a higher temperature than the ceramic matrix composite... allowing the layer to be fired at a higher temperature than the forming temperature of the composite body
Data Source
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Figure 3
AI summary
A method of forming a ceramic matrix composite component is provided. The method includes the steps of: providing a pattern element; coating the pattern element with a ceramic slurry; drying the slurry to form a ceramic layer; forming a ceramic matrix composite body on a surface of the ceramic layer to produce a ceramic matrix composite component with the ceramic layer attached thereto.