3D Printed Ceramic Filter for Molten Metal Filtration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ceramic filters for molten metals face challenges in achieving a balance between tortuosity and structural stability, with previous methods resulting in fragile ligaments or high particle occupancy, which can lead to inclusion issues during filtration.
Innovation Solution
A method using three-dimensional printing to create a filter medium with multiple layers of geometric cages, where each layer is held in a fixed spaced-apart relationship by peripheral and spacer members, allowing for precise control of pore size and tortuosity through the use of partially-truncated or fully-truncated octahedron shapes, and optionally coated with a ceramic slurry for increased stability and tortuosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ceramic filters are formed using traditional sintering methods with high particle occupancy, then structural stability is improved, but tortuosity is reduced and inclusion formation increases
Solution Approach 1:
The patent employs a reticulated foam structure with controlled porosity where ligaments form a three-dimensional network. This porous architecture provides both structural stability and adequate tortuosity for filtration, allowing molten metal to follow a tortuous path while maintaining filter integrity under thermal and mechanical stress.
Solution Approach 2:
The filter combines ceramic particles embedded in a ligament matrix to create a composite structure. This composite approach allows the filter to achieve both structural stability from the ceramic material and controlled tortuosity from the ligament network, resolving the contradiction between stability and filtration precision.
2Manufacturing precision
If ceramic filters use fragile ligaments to achieve high tortuosity, then filtration precision is improved, but structural stability deteriorates and ligaments break off causing inclusions
Solution Approach 1:
The patent optimizes ligament dimensions by controlling the diameter and thickness parameters within specific ranges. This parameter optimization ensures ligaments are sufficiently thick to maintain structural stability and prevent breakage, while still providing adequate tortuosity for effective filtration of molten metal impurities.
3Manufacturing precision
If water filters use micron-level pore sizes, then filtration precision is improved, but flow area is reduced and molten metal cannot pass quickly
Solution Approach 1:
The patent transitions from two-dimensional filtration surfaces to a three-dimensional reticulated structure with ligaments extending throughout the filter volume. This dimensional change creates multiple flow paths in three dimensions, increasing the effective flow area while maintaining adequate tortuosity for filtration, thus resolving the contradiction between precision and productivity.
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 solution provides a stable and effective filter medium that maintains structural integrity while ensuring efficient filtration of molten metals by balancing tortuosity and porosity, reducing the risk of inclusion formation.
Implementation Method 1
When the slurry was fired, the polystyrene would burn out, leaving a network of randomly-directed ligaments that supported a tortuous flow path of pores previously occupied by the spheres
Implementation Method 2
The '298 patent describes using a stereolithography technique to form the reticulated network by selective laser activation of a resin that contains the ceramic material and is photopolymerizable
Implementation Method 3
The polymer-ceramic composite network is then reduced to ceramic by known techniques, including burnout
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A filter element, useful for filtering molten metals and the like, is made from a precursor or template (10) having at least two layers (20). Each layer is assembled from three-dimensional geometric cages (22), joined in fixed relationship to each other: Some embodiments include a peripheral member (26) that encompasses the layer. In such cases, spacer members (28) can span the peripheral members to hold the layers in fixed spaced-apart relationship. In other embodiments, at least some of the cages in adjacent layers can be joined in fixed relationship, providing the spaced-apart relationship. The cages can be built from linear segments of a material joined in a pattern based on the edges of the geometric solid. The template may be formed by an automated technique, such as three-dimensional printing. If manufactured from a polymer, the precursor is coated with a ceramic slurry and calcined to provide the filter element.