SiC Fluidic Module Fabrication with Embedded Passage Mold
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Solution Overview
Problem
The existing methods for fabricating silicon carbide (SiC) structures with internal features, such as tortuous passages, are challenging due to the fragility of passage molds, which can be damaged during removal and handling, and require improved alignment and support to simplify the fabrication process.
Innovation Solution
A process involving pressing a binder-coated ceramic powder to form a pressed body, positioning a positive passage mold, covering with additional powder, pressing, and sintering to create a unified ceramic fluidic module with a tortuous passage extending through it, using embossed features or pre-pressed ceramic inserts for alignment and support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the existing lost-material approach is used to fabricate SiC structures with internal passages, then smooth-surfaced tortuous passages can be formed, but the passage molds are fragile and can be damaged during removal and handling
Solution Approach 1:
The passage mold is pre-formed by injecting molten mold material into a silicone mold master, creating a robust positive passage mold before it needs to be used in the ceramic body fabrication process. This preliminary formation ensures the mold has sufficient strength to withstand subsequent handling and pressing operations
Solution Approach 2:
The mold material parameters are changed from soft silicone (used in the master mold) to a harder, more durable material that can withstand the pressing and handling forces. This parameter change in material hardness and strength prevents mold damage while maintaining the ability to form precise passage geometries
2Ease of operation
If manual processes are used for removing passage molds from silicone mold masters, then flexibility is maintained, but the process is time-consuming and prone to mold damage
Solution Approach 1:
The manual mechanical removal process is replaced with an automated injection molding process where molten mold material is injected into the silicone mold master under pressure. This mechanical substitution automates the mold formation, reducing manual labor and time while improving consistency and reducing mold damage risk
Solution Approach 2:
The mold material undergoes phase transition from molten state to solid state during injection into the silicone mold master. This phase change allows the material to flow easily during injection (like a liquid) and then solidify to form a rigid, durable positive passage mold, combining the benefits of easy forming with final structural integrity
3Ease of operation
If passage molds are partially suspended during transfer into pressing dies, then positioning flexibility is maintained, but alignment precision deteriorates
Solution Approach 1:
A support structure or intermediary mechanism is introduced to hold the passage mold in the correct position during transfer and pressing operations. This intermediary ensures the mold maintains precise alignment with the pressing die and other components, eliminating the alignment errors that occur with manual suspension and positioning
Solution Approach 2:
The pressing process is designed so that the passage mold and ceramic powder are pressed simultaneously under uniform pressure conditions. This equipotential pressing ensures that the mold remains stable and aligned throughout the process, preventing misalignment that would occur with sequential or non-uniform pressing operations
4Strength
If high density and closed-porosity are achieved in SiC ceramic bodies, then mechanical integrity is improved, but the fabrication process becomes more challenging
Solution Approach 1:
The ceramic powder is pre-mixed with binder and pre-formed into a green body with the passage mold embedded before final sintering. This preliminary formation ensures proper density distribution and structural integrity are achieved before the high-temperature sintering process, making it easier to obtain high-density, closed-porosity final products
Solution Approach 2:
The ceramic body is formed as a composite structure with the passage mold embedded in the ceramic matrix. This composite approach allows the mold to define the passage geometry while the ceramic material provides the high-density, closed-porosity structure, combining the benefits of both materials in a single fabrication process
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 allows for the practical production of high-density, closed-porosity SiC fluidic modules with smooth-surfaced tortuous passages, reducing mold damage and simplifying the fabrication process while ensuring alignment and support, resulting in improved mechanical integrity and fluid tightness.
Implementation Method 1
pressing a first volume of a binder-coated ceramic powder to form a first pressed body
Implementation Method 2
pressing the second volume of binder-coated ceramic powder, the passage mold, and the first pressed body to form a second pressed body
Implementation Method 3
heating the second pressed body to remove the passage mold
Implementation Method 4
sintering the second pressed body to form the ceramic fluidic module
Data Source
AI summary
A module and process for forming a ceramic fluidic module (300) that includes a unified closed-porosity ceramic body (200) and a tortuous fluid passage (P) that extends through the body (200). The body (200) has a first mean density within a first layer (222) that is greater than a second mean density within a second layer (226). The first and second layers (222, 226) are axially serially arranged between opposed major surfaces (228, 229) of the body (200). The fluid passage (P) adjoins the first layer (222) of the body (200). The process includes pressing a first volume of ceramic powder (120) to form a pre-pressed body (150). A passage mold (130) is then positioned on the pre-pressed body (150). The pre-pressed body (150) and the passage mold (130) are then covered with a second volume of ceramic powder (125). The body (150), the mold (130), and the second volume of ceramic powder (125) are then pressed to form a pressed body (160). The pressed body (160) is heated and sintered to form the ceramic fluidic module (300).