Slip Densification of Corrugated Ceramic Fiber Preforms Without Machining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for densifying fibrous textures in ceramic matrix composites require additional machining steps to achieve a smooth surface, which increases costs and reduces thermomechanical strength, complicating the manufacturing process.
Innovation Solution
A process involving an injection mold with a membrane having a stiffened zone with a Young's modulus greater than 200 GPa, placed to contact the crests of undulations in the fibrous texture, and a controlled pressure differential between compaction and injection pressures to prevent excess thickness during densification, ensuring a smooth surface without additional machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional machining steps are used to achieve a smooth surface on the densified fibrous texture, then the surface quality is improved, but the manufacturing complexity increases and thermomechanical strength is reduced
Solution Approach 1:
The membrane with the stiffened zone is placed on the fibrous texture before densification occurs, establishing a reference surface in advance. This preliminary action allows the matrix to densify up to the membrane level, automatically forming a smooth surface without requiring subsequent machining operations.
Solution Approach 2:
The membrane acts as an intermediary element between the injection mold and the fibrous texture. The stiffened zone of the membrane serves as a mediator that defines the final surface level, preventing excess matrix growth and ensuring a smooth surface finish during the densification process itself.
2Manufacturing precision
If additional machining steps are used to achieve a smooth surface, then the surface quality is improved, but the thermomechanical strength is reduced
Solution Approach 1:
By placing the membrane with the stiffened zone before densification, the surface smoothing action is performed during the forming process itself rather than through subsequent machining. This eliminates mechanical removal of material that would compromise the thermomechanical strength of the ceramic matrix composite.
3Manufacturing precision
If the membrane is made more rigid to prevent deformation during compaction, then the surface smoothness is improved, but the membrane becomes more difficult to conform to the fibrous texture contours
Solution Approach 1:
The membrane is designed with non-uniform properties: a stiffened zone with high rigidity (Young's modulus > 200 GPa) at the surface contact area to ensure smoothness, while the rest of the membrane remains flexible to conform to the fibrous texture contours and allow proper placement and compaction.
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 process achieves a smooth surface on the fibrous texture without excess thickness, maintaining mechanical strength and simplifying the manufacturing process by preventing matrix growth at the stiffened zone, while allowing a wide range of compaction pressures.
Implementation Method 1
a membrane comprising a stiffened zone, the membrane being intended to be placed between a fibrous texture present in the molding cavity and the counter-mold and the stiffened zone of the membrane having a Young's modulus greater than 200 GPa
Implementation Method 2
a slip injection step which consists of impregnating the fibrous texture with a suspension of ceramic particles or slip which penetrates the porosity of the fibrous texture
Implementation Method 3
the densification of the pre-densified fibrous texture by infiltrating a slurry into the porosity of the pre-densified fibrous texture, the slurry being injected into the molding chamber laterally to the stiffened area of the membrane under injection pressure
Data Source
Figure 1
Figure 2A
Figure 2B~3
AI summary
The invention relates to a method for densifying a fibrous texture made of ceramic material used in injection equipment comprising: - a mould cavity defined between a mould and a counter-mould, the mould cavity defining an internal space; and - a membrane comprising a stiffened zone, the membrane being intended to be placed between a fibrous texture present in the mould cavity and the counter-mould, and the stiffened zone of the membrane having a Young's modulus greater than 200 GPa, the method comprising: - placing (110) a predensified fibrous texture in the mould cavity, the predensified fibrous texture having corrugations on the surface and placing the membrane on the predensified fibrous texture in such a way that the stiffened zone of the membrane is in contact with the peaks of the corrugations of the predensified fibrous texture; - closing (120) the injection equipment by placing the counter-mould on the membrane and applying a compaction pressure (Pcompaction) to the membrane so as to keep the stiffened zone of the membrane in contact with the peaks of the corrugations of the predensified fibrous texture; and - densifying (130) the predensified fibrous texture by infiltrating a slip into the porosity of the predensified fibrous texture, the slip being injected into the mould chamber laterally to the membrane at an injection pressure (Pinjection) such that the difference in pressure between the compaction pressure and the injection pressure is between 0.5 x 10^5 Pa and 6 x 10^5 Pa.