Refractory Filter Closed Edge Production Method
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Solution Overview
Problem
Conventional ceramic foam filters used for molten metal filtration have poor mechanical strength, leading to edge breakage and reduced filtration efficiency, and increasing the slurry impregnation to enhance strength results in higher weight, reduced porosity, and increased energy consumption due to higher heat capacity.
Innovation Solution
A method for producing ceramic foam filters with a closed edge by applying a liquid organic coating to the reticulated foam substrate, followed by impregnation with a refractory slurry and firing, which creates a unitary closed edge that enhances edge strength without increasing the filter's interior refractory material, resulting in lower weight and higher porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of slurry used to impregnate the foam is increased to increase filter strength, then the mechanical strength is improved, but the filtration efficiency is reduced due to higher weight and reduced porosity
Solution Approach 1:
The patent applies a protective coating specifically to the edge surfaces of the filter where mechanical strength is most needed, while keeping the interior foam structure lightweight and highly porous for optimal filtration. This localized reinforcement resolves the contradiction by providing strength where required without compromising the overall porosity and filtration efficiency of the filter body.
2Strength
If the amount of slurry used to impregnate the foam is increased to increase filter strength, then the mechanical strength is improved, but the energy consumption increases due to higher heat capacity
Solution Approach 1:
By applying coating only to the edge surfaces rather than impregnating the entire foam structure, the patent minimizes the additional mass and heat capacity of the reinforced filter. This localized approach provides the necessary mechanical strength at the edges while keeping the overall energy consumption during heating to operating temperature comparable to or lower than conventional fully impregnated filters.
3Strength
If the amount of slurry used to impregnate the foam is increased to increase filter strength, then the mechanical strength is improved, but the filter weight increases
Solution Approach 1:
The protective coating is applied specifically to the edge surfaces of the filter where mechanical strength is most critical during handling and installation. This localized reinforcement provides the necessary strength improvement while minimizing the additional weight compared to uniform impregnation of the entire foam structure.
Solution Approach 2:
Instead of applying slurry uniformly throughout the entire foam structure, the patent applies coating only to the edge surfaces where it is most needed. This partial action provides sufficient mechanical strength for handling and installation without the excessive weight penalty of full impregnation.
4Speed
If the filter pores are made larger to increase metal flow rate, then the flow rate is improved, but the filtration efficiency is reduced
Solution Approach 1:
The patent maintains the original pore size distribution in the interior foam structure to ensure optimal filtration efficiency, while the protective coating on the edges provides mechanical strength. This allows the filter to achieve both high filtration efficiency through the tortuous path in the foam and adequate mechanical strength at the edges without compromising either property.
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 closed edge filters exhibit improved mechanical strength, increased porosity, and enhanced filtration efficiency while maintaining or improving edge strength, allowing for higher metal flow rates and reduced energy consumption.
Implementation Method 1
applying a liquid comprising an organic coating component to the first surface; solidifying the organic coating component to form a filter precursor having a continuous volatilisable coating on the first surface
Implementation Method 2
impregnating the filter precursor with a slurry comprising particles of a refractory material, a binder and a liquid carrier; drying and firing the impregnated filter precursor
Implementation Method 3
drying and firing the impregnated filter precursor to form the filter having a closed edge
Data Source
AI summary
A method for the production of closed edge filters suitable for filtering molten metal and filters made by such a method. The method comprises: providing a reticulated foam substrate having at least one first surface for forming a side face of the filter and two opposed second surfaces for forming the through-flow faces of the filter; applying a liquid comprising an organic coating component to the first surface; solidifying the organic coating component to form a filter precursor having a volatilizable coating on the first surface; impregnating the filter precursor with a slurry comprising particles of a refractory material, a binder and a liquid carrier; and drying and firing the impregnated filter precursor to form the filter having a closed edge.