Ceramic Filter Pore Size Control via Lapping
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Solution Overview
Problem
Existing methods for manufacturing ceramic filters with controlled pore sizes are inefficient, resulting in weak and expensive filters unsuitable for many applications, particularly in microfiltration and blood separation, where precise pore sizes are required.
Innovation Solution
A method involving the fabrication of a ceramic precursor element with flared pores, where the polymer is burnt off during sintering, and a controlled thickness is removed from the surface to achieve specific pore sizes, using a lapping machine and computer-controlled abrasion to automate the process, ensuring precise control over pore dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional track-etch or laser drilling techniques are used to create pores in polymeric membranes, then pore formation is achieved, but the resulting filters are weak and expensive
Solution Approach 1:
The invention changes the material parameter from polymeric to ceramic, which fundamentally improves filter strength and durability. The ceramic material provides mechanical robustness while maintaining porosity, resolving the weakness issue of traditional polymeric filters.
Solution Approach 2:
The invention performs preliminary pore formation in the green body (unsintered ceramic) using phase separation techniques before sintering. This preliminary action creates the pore structure in advance, avoiding the need for complex post-processing techniques like track-etch or laser drilling, thus reducing manufacturing complexity.
2Manufacturing precision
If ceramic materials are used for microfiltration, then filtration performance should be improved, but there is no easy technique for producing on-demand defined circular pore sizes
Solution Approach 1:
The invention uses phase separation during sintering to naturally define circular pore sizes. By controlling the phase separation parameters (temperature, time, composition), precise pore size control is achieved on-demand without complex manufacturing techniques.
Solution Approach 2:
The ceramic body performs self-service by using phase separation during sintering to automatically create the desired pore structure. The material itself generates the pores through controlled phase separation, eliminating the need for external pore-forming techniques and simplifying manufacturing.
3Manufacturing precision
If a controlled thickness portion is removed from the first surface to open flared pores, then precise pore size control is achieved, but additional processing steps are required
Solution Approach 1:
The invention creates flared pores with a broader opening at the first surface during the sintering process itself, as a preliminary action. This preliminary shaping allows subsequent controlled removal of material to achieve precise pore sizes more easily, as the flared geometry provides a built-in advantage for size control.
Solution Approach 2:
The invention applies local quality by creating flared pores with different geometries at different locations (narrower at the apex, broader at the opening). This local variation in pore geometry allows for better control over the final pore size after material removal, as the flared shape provides a larger margin for error in the opening region.
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 enables the production of ceramic filters with consistent, controlled pore sizes, enhancing filtration efficiency and reducing the loss of red blood cells during blood filtration, while being cost-effective and suitable for various applications, including blood separation and microfiltration.
Implementation Method 1
During firing the polymer material is burnt off leaving flared apertures in the sintered ceramic
Implementation Method 2
removing a controlled thickness portion of said first surface to open said flared pores to said controlled filter channel opening size
Data Source
Figure 1a~1b
Figure 2a~3
Figure 4~5
AI summary
We describe apparatus for controlling the filter channel opening size of a ceramic filter element, said ceramic filter element having flared pores, the apparatus comprising: a lapping machine having a lapping plate; and a filter holder to hold a ceramic filter element for controlled lapping of said flared pores; wherein said filter holder comprises: a filter element mount to mount a filter element to be lapped such that a surface of said filter element lies substantially flush with a lower face of said filter holder; an adjustable actuator to controllably move said surface of said filter element so that it remains substantially flush or projects beyond said lower face of said filter holder during lapping; and means for urging said filter holder towards said lapping plate.