Refractory Filter Composition for Low-Friability Molten Metal Filtration
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Solution Overview
Problem
Existing refractory filters for molten metals, particularly zirconia-based filters, suffer from high friability, density, and cost, leading to contamination and difficulty in priming due to high zirconia content, and lack a tortuous path for filtration.
Innovation Solution
A refractory filter composition comprising 60-90 wt% alumina, 8-30 wt% zirconia, and 3-20 wt% magnesia, with optional substitution of magnesia by ceria, and a powdered composition with low reactive alumina content, forming a filter with a network of interconnecting strands for multiple tortuous paths, and optionally using 3D printing for fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high zirconia content (up to 95% by weight) is used in the filter, then high temperature resistance is improved, but cost increases and friability worsens
Solution Approach 1:
The patent applies composite materials by combining zirconia with alumina and magnesia in specific proportions (8-30 wt% zirconia, 60-90 wt% alumina, 3-20 wt% magnesia). This composite refractory material maintains high temperature resistance while reducing friability and cost compared to pure zirconia filters. The synergistic effect of multiple materials resolves the contradiction between temperature resistance and reliability.
Solution Approach 2:
The patent changes the compositional parameters of the refractory material by limiting zirconia content to 8-30 wt% and adding specific amounts of alumina and magnesia. This parameter optimization allows the filter to achieve adequate high temperature resistance while significantly reducing friability and cost, resolving the technical contradiction.
2Temperature
If high zirconia content is used in the filter, then high temperature resistance is improved, but density increases making priming difficult
Solution Approach 1:
By using composite refractory materials with controlled zirconia content (8-30 wt%) combined with alumina and magnesia, the filter achieves high temperature resistance while maintaining lower density. This reduces the difficulty of priming compared to pure zirconia filters, resolving the contradiction between temperature resistance and ease of operation.
3Ease of manufacture
If conventional filter structures (cellular or pressed) are used, then manufacturing is simplified, but tortuous path for filtration is lost
Solution Approach 1:
The patent employs porous refractory material with controlled porosity (40-70%) to create a tortuous flow path for molten metal. This porous structure maintains adequate filtration performance while being manufacturable using conventional techniques, resolving the contradiction between ease of manufacture and filtration reliability.
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 new filter design reduces friability and density, enhances mechanical strength, and lowers production costs while maintaining high temperature resistance and filtration capacity, capable of handling significant amounts of molten metal without rupture.
Implementation Method 1
refractory filter for filtering molten steel, the refractory filter comprising refractory material... capable of withstanding elevated temperatures
Implementation Method 2
enhances mechanical strength... the friability of zirconia-based foam filters can result in small pieces breaking off the filter
Data Source
AI summary
A refractory filter suitable for filtering molten metal, such as steel, and a method and powdered composition for producing the filter. The filter comprises refractory material, the refractory material comprising: 60-90 wt % alumina; 8-30 wt % zirconia; and 3-20 wt % magnesia. The powdered composition comprises: 60-90 wt % alumina; 8-30 wt % zirconia; and 3-20 wt % magnesia, wherein the powdered composition comprises less than 12.5 wt % reactive alumina, calcined alumina or a mixture thereof, and wherein the remainder of the alumina is tabular alumina. The method comprises: providing a powdered composition in accordance with the invention; forming a filter precursor from the powdered composition and a liquid component; and firing the filter precursor to form a refractory filter.