Bladder Cast Slurry Infiltration for CMC Surface Finish
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Solution Overview
Problem
Existing slurry infiltration methods for reinforced ceramic matrix composites (CMCs) face challenges in achieving uniform surface finish and reducing post-processing steps, often resulting in excess cured slurry on the surface of components, which can be damaging and require extensive removal processes.
Innovation Solution
The use of inflatable bladders within a mold body to promote even slurry infiltration and contact with the CMC substrate, allowing for improved surface finish and reduced post-processing by inflating the bladders to conform to the component's surface and enhance slurry penetration, followed by drying and deflation for a smooth bladder-cast finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional slurry infiltration methods are used, then the CMC substrate can be infiltrated with slurry, but excess cured slurry is left on the surface requiring extensive post-processing
Solution Approach 1:
The mold body is made dynamically adaptable by incorporating inflatable bladders that can change volume and shape. The bladders are inflated to press against the CMC substrate surface, dynamically conforming to the substrate's geometry and applying pressure to ensure complete slurry infiltration without excess slurry on the surface, thereby eliminating the need for extensive post-processing.
Solution Approach 2:
The physical state and pressure parameters of the slurry are controlled during infiltration. By inflating the bladders, pressure is applied to the slurry and substrate interface, changing the pressure parameter to ensure complete infiltration. The slurry is kept in a controlled fluid state during the process, and the pressure change enables the slurry to penetrate fully without remaining as excess cured slurry on the surface.
2Manufacturing precision
If the mold body is made rigid and fixed, then the structure is simple and stable, but it cannot conform to complex substrate surfaces resulting in poor surface finish
Solution Approach 1:
The mold body transitions from a rigid fixed structure to a dynamic adaptable structure through the inflatable bladders. The bladders can be inflated or deflated to conform to the specific geometry of the CMC substrate, allowing the mold to adapt to complex surfaces while maintaining a relatively simple overall mold body structure.
Solution Approach 2:
The mold body is segmented into multiple inflatable bladders that can be independently controlled. Each bladder can be inflated or deflated separately to conform to different portions of the substrate surface, allowing complex geometries to be accommodated through combination of simpler bladder units rather than requiring a completely complex monolithic mold structure.
3Manufacturing precision
If slurry is introduced to fill all inner spaces, then complete infiltration is achieved, but excess slurry remains on the surface
Solution Approach 1:
The inflatable bladders dynamically adjust the volume and pressure distribution within the mold cavity. By controlling bladder inflation, the system ensures slurry fills all inner spaces of the CMC substrate while simultaneously preventing excess slurry from remaining on the surface. The bladders apply localized pressure to promote infiltration while the overall volume control prevents surplus slurry accumulation.
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 method results in a composite article with a substantially smooth surface finish and reduced post-processing steps, enhancing the quality and efficiency of the CMC manufacturing process.
Implementation Method 1
A molten alloy infiltrant material including silicon (Si) may then be introduced into the green composite article using capillary forces to densify the structure
Implementation Method 2
inflating at least one bladder coupled to the mold body that is disposed within the cavity. During inflation, a surface of the at least one bladder in an inflated configuration may contact at least one surface of the CMC substrate
Implementation Method 3
drying the slurry to remove at least a portion of the carrier material to form an infiltrated CMC that includes the solid particles from the slurry
Data Source
AI summary
A method of forming a bladder cast ceramic matrix composite (CMC) article including infiltrating a CMC substrate positioned in a cavity of a mold body with a slurry. The CMC substrate includes reinforcement material defining inner spaces. The slurry includes solid particles and a carrier material. During infiltration, the slurry at least partially fills at least a portion of the inner spaces of the CMC substrate. The method also includes inflating at least one bladder that is coupled to the mold body and disposed within the cavity such that a surface of the at least one bladder in an inflated configuration contacts at least one surface of the CMC substrate. The method also includes drying the slurry to remove at least a portion of the carrier material form an infiltrated CMC and deflating the at least one bladder.