Ceramic Foam With Narrow Cell Size Distribution
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Solution Overview
Problem
Existing methods for manufacturing porous ceramic foams face challenges in achieving a homogeneous structure with large dimensions, high porosity, and a balanced compromise between pressure drop and filtration efficiency while maintaining mechanical strength, often involving toxic gas release and difficulty in controlling polymerization conditions.
Innovation Solution
A ceramic foam with nested cells and interconnected windows, manufactured through a method involving a mixture of ceramic powder, gelling agent, and foaming agent, sheared at high temperature, then gelled and dried to achieve a narrow cell size distribution and controlled porosity, without the need for stabilizing agents, allowing for thick and structurally stable foams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a pore-forming agent is added to ceramic slip and burned during firing, then porosity is created, but toxic gas is released and homogeneous structure in thick parts is difficult to achieve
Solution Approach 1:
The patent removes the pore-forming agent step entirely by using a different mechanism - mechanical foam generation through high-shear mixing of ceramic slurry with gas. This extracts the harmful pyrolysis process while retaining the porosity creation function, eliminating toxic gas release during manufacturing.
Solution Approach 2:
The patent replaces the chemical process (burning pore-forming agent) with a mechanical process (high-shear mixing to generate and distribute gas bubbles). This substitution creates porosity through physical means rather than chemical decomposition, avoiding toxic emissions.
2Shape
If polyurethane foam is used as a template and burned, then ceramic foam structure is obtained, but CN-bonded gases are released and pores smaller than 200 μm are difficult to produce
Solution Approach 1:
The patent extracts and eliminates the polyurethane foam template step by directly generating gas bubbles in the ceramic slurry through mechanical mixing. This removes the source of CN-bonded gases while preserving the foam structure formation capability through controlled bubble distribution.
Solution Approach 2:
The patent changes the key parameter of pore size from being limited to >200 μm (as in prior art) down to 50-200 μm by controlling the mechanical mixing parameters - specifically the shear rate, mixing time, and gas injection rate during foam generation. This enables production of finer pores without toxic gas release.
3Length of stationary object
If foam thickness exceeds 60 mm, then large dimensions are achieved, but homogeneous structure cannot be maintained
Solution Approach 1:
The patent applies preliminary action by thoroughly pre-mixing the ceramic slurry to ensure uniform viscosity and composition before foam generation. This preliminary homogenization ensures that when gas bubbles are introduced and distributed through high-shear mixing, they are uniformly dispersed throughout thick sections (up to 100 mm) rather than creating gradients or defects.
4Quantity of substance
If water content is increased to 45-50% by weight, then foam consistency is improved, but drying becomes difficult for thick foams
Solution Approach 1:
The patent changes the water content parameter from the conventional 45-50% down to 30-40%. This parameter adjustment reduces the drying burden for thick foams while still maintaining adequate consistency and workability during the foam generation and gelling processes, making industrial manufacturing of thick parts feasible.
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 method enables the production of ceramic foams with high porosity and mechanical strength, achieving a better balance between pressure drop and filtration efficiency, suitable for industrial-scale manufacturing of thick parts with complex shapes.
Implementation Method 1
preparation of a solution containing a biogel, also called 'hydrocolloid', and maintaining at a temperature above the gelling temperature of the solution
Implementation Method 2
firing the foam obtained
Implementation Method 3
mixing said suspension and said solution, with the addition of a foaming agent, until a foam is obtained
Implementation Method 4
drying then firing the foam obtained
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
Disclosed is a ceramic foam that is obtained by a method in accordance with the present invention and has a plurality of interlinked cells which are delimited by ceramic walls and are interconnected by interconnection windows, the walls delimiting the cells being formed by sintering grains, this agglomeration leaving interstices between the grains, the ceramic foam having a total porosity that is higher than 40%, the ratio (d90-d10)/d50 being lower than 0.15, the percentiles d10, d50 and d90 being the cell sizes corresponding, respectively, to the percentages 10%, 50% and 90%, in number, respectively, on the cumulative distribution curve of the cell sizes arranged in ascending order, the size of a cell being the equivalent diameter of its area shown in a digital photo of a cross section of the foam.