Slotted Ceramic Coatings for CMAS Resistance
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Solution Overview
Problem
Thermal barrier coatings (TBCs) in gas turbine engines face strain tolerance issues due to infiltration of molten calcium-magnesium-alumino-silicate (CMAS) deposits, leading to spallation and reduced component life, especially at high temperatures where ceramic TBCs become vulnerable to environmental dust and particulates.
Innovation Solution
A ceramic coating with local slotting is introduced, featuring a combination of linear and non-linear slots that form segments of the coating material, designed to prevent complete infiltration of molten CMAS and maintain thermal strain tolerance by reducing capillary forces and acting as 'crack-stoppers' to prevent spallation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional TBC designs with pores and cracks are used to improve strain tolerance, then the coating can accommodate thermal expansion, but molten CMAS infiltrates these features reducing strain tolerance and coating durability
Solution Approach 1:
The TBC is divided into multiple segments by creating an array of through-coating slots that intersect to form a grid pattern. This segmentation prevents continuous infiltration paths for molten CMAS while maintaining the coating's overall structural integrity and thermal expansion accommodation capabilities.
Solution Approach 2:
Material is removed from the TBC by creating slots that extend through the coating thickness, extracting the continuous ceramic matrix to create a segmented structure. This extraction eliminates the continuous pathways that allow CMAS infiltration while preserving the coating's functional properties.
2Strength
If ceramic TBCs are used to protect metal substrates at high temperatures, then the substrate is protected from thermal damage, but the coating becomes vulnerable to CMAS infiltration and spallation
Solution Approach 1:
The continuous ceramic coating is segmented into isolated regions by through-coating slots, preventing molten CMAS from infiltrating through the coating while maintaining thermal protection of the substrate. The segmented structure breaks infiltration pathways without compromising substrate protection.
Solution Approach 2:
The TBC has different structural qualities in different regions - the segments between slots maintain intact ceramic protection, while the slots themselves provide strain tolerance and prevent CMAS infiltration. This local differentiation optimizes both protection and resistance to harmful factors.
3Reliability
If the TBC is made dense to improve CMAS resistance, then infiltration is reduced, but strain tolerance and compliance decrease leading to early spallation
Solution Approach 1:
The coating is segmented into isolated segments by intersecting slots, which prevents CMAS infiltration while maintaining strain tolerance. The segmented structure allows thermal expansion and contraction without generating the stresses that cause spallation in dense coatings.
Solution Approach 2:
Instead of modifying the coating's density in the thickness dimension, the solution adds a new dimension of segmentation by creating through-coating slots. This dimensional approach to structuring the coating provides both CMAS resistance and strain tolerance simultaneously.
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 slotted ceramic coating enhances CMAS resistance and heat transfer performance, improving the durability and life of components by preventing complete CMAS infiltration and delaying spallation, thus reducing unscheduled maintenance and operating costs.
Implementation Method 1
designed to prevent complete infiltration of molten CMAS and maintain thermal strain tolerance by reducing capillary forces
Implementation Method 2
a metal substrate is coated with a TBC that is a ceramic insulating material to reduce the service temperature of the underlying metallic segments
Data Source
AI summary
A coated component for a gas turbine engine is provided. The coated component includes a substrate having a surface and a ceramic coating. The ceramic coating includes one or more linear slots and one or more non-linear slots. The one or more non-linear slots intersect the one or more linear slots. The plurality of linear slots and the plurality of non-linear slots form segments of ceramic coating material.