CMC Gas Turbine Component with Hermetic Coating Openings
Solution Overview
Problem
Ceramic matrix composite (CMC) turbine components degrade due to interactions with combustion gases at elevated temperatures, leading to volatilization, and existing environmental barrier coatings (EBCs) are prone to spallation, exposing the CMC to further degradation.
Innovation Solution
A gas turbine component with a CMC substrate and a hermetic coating that includes strategically positioned openings to create a pressure differential between a compressed, dry fluid and a wet fluid stream, reducing or eliminating volatilization by displacing wet fluid away from the CMC substrate, thereby protecting it from hydrolysis and deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If CMC turbine components are used to operate at higher temperatures, then efficiency and power output are improved, but the CMC substrate degrades due to volatilization from interaction with combustion gases
Solution Approach 1:
A hermetic coating is applied as an intermediary layer between the CMC substrate and the combustion gases. This coating includes openings that allow compressed dry air to pass through and displace wet combustion gases away from the CMC substrate, preventing direct interaction and volatilization while allowing the substrate to operate at high temperatures for improved power output
Solution Approach 2:
Compressed dry air is introduced through openings in the hermetic coating to create a pneumatic displacement effect. The pressurized dry air flow pushes wet combustion gases away from the CMC substrate surface, using gas pressure and flow dynamics to protect the substrate from chemical degradation while maintaining high operating temperatures
2Reliability
If EBCs are applied to protect CMC from degradation, then reliability is improved, but the EBCs are prone to spallation under thermo mechanical strain, exposing CMC to further degradation
Solution Approach 1:
The hermetic coating with openings acts as a new intermediary system that eliminates the need for traditional continuous EBCs. By introducing compressed dry air through discrete openings, the system achieves protection without requiring a thick, brittle coating layer that is susceptible to spallation under thermal stress
Solution Approach 2:
Instead of applying a uniform continuous coating across the entire surface, the protective function is achieved locally through strategically positioned openings in the hermetic coating. This localized approach allows protection where needed while reducing overall coating material and stress accumulation that leads to spallation
3Reliability
If hermetic coating with openings is used to protect CMC substrate, then durability is enhanced, but device complexity increases
Solution Approach 1:
The hermetic coating is segmented with discrete openings rather than being a continuous solid layer. This segmentation allows the coating to accommodate thermal stress more effectively while the openings provide controlled access for dry air flow, achieving enhanced durability through a structured yet manageable design
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 significantly enhances the durability and service lifetime of CMC components, allowing for increased efficiency and power output while reducing the need for frequent replacements, and enables repair of components that would otherwise require replacement.
Implementation Method 1
reduces or eliminates volatilization of the CMC substrate by displacing the wet fluid away from the CMC substrate with a compressed, dry fluid
Data Source
Figure 1
Figure 2~3
AI summary
Components (101) are disclosed which include a CMC substrate (103) having a first surface (105) and a second surface (107). The first surface (105) is in fluid communication with a compressed, dry fluid (109), and the second surface (107) is in fluid communication with a wet fluid stream (111) and includes a hermetic coating (113). The components (101) further include at least one opening (201) extending from the first surface (105) through a portion (203) of the CMC substrate (103), wherein, upon removal of a fragment of one or both of the hermetic coating (113) and the CMC substrate (103), the at least one opening (201) selectively permits a flow (303) of the compressed, dry fluid (109) to the second surface (107). In one embodiment, the component (101) is a gas turbine component, the wet fluid stream (111) is a hot combustion stream, the hermetic coating (113) is an environmental barrier coating (119), and the flow (303) reduces or eliminates volatilization of the CMC substrate (103). Methods for forming the components (101) are also disclosed.