Environmental Barrier Coating Surface Roughness Reduction
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Solution Overview
Problem
Current environmental barrier coating (EBC) processes, such as plasma spray, result in surface roughness exceeding 5.08µm (200 micro inch) Ra, which is undesirable for aerodynamic design in advanced turbine engines, necessitating a method to improve surface roughness.
Innovation Solution
A water-based slurry comprising a primary transition or outer material and sintering aids like iron oxide, gallium oxide, or a combination of Lnb rare earth metal and SiO2 is applied to a plasma sprayed EBC, followed by drying and sintering to achieve a surface roughness between 1.02 µm (40 micro inch) Ra and 5.08 µm (200 micro inch) Ra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma spray process is used to apply EBC, then the coating can be applied efficiently, but the surface roughness exceeds 5.08μm (200 micro inch) Ra which is undesirable for aerodynamic design
Solution Approach 1:
A slurry coating is applied over the plasma sprayed EBC before final sintering. This preliminary coating layer fills in the surface irregularities and roughness features of the underlying plasma sprayed coating, creating a smoother final surface without requiring re-spraying
Solution Approach 2:
The slurry composition is specifically designed with fine particles and binders that can flow into and fill surface voids. The slurry is then sintered at controlled temperatures to densify the coating and reduce surface roughness from greater than 5.08μm Ra to below 5.08μm Ra, achieving the required aerodynamic surface quality
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 method effectively reduces surface roughness of EBCs to a desirable range, enhancing their aerodynamic performance and mechanical properties while maintaining a hermetic seal against high-temperature environments.
Implementation Method 1
drying the environmental barrier coating having the applied slurry
Implementation Method 2
sintering the component to produce a component having an improved surface roughness
Data Source
Figure 1
Figure 2~3
AI summary
A method for improving surface roughness of an environmental barrier coating (12) comprising: providing a component (10) having a plasma sprayed environmental barrier coating; applying a slurry to the environmental barrier coating of the component, the slurry comprising a transition layer slurry or an outer layer slurry; drying the environmental barrier coating having the applied slurry; and sintering the component to produce a component having an improved surface roughness wherein the slurry comprises: water; a primary transition material, or a primary outer material; and at least one slurry sintering aid.