Porous Ceramic Manufacturing via Shear-Thickening Stabilization
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Solution Overview
Problem
Existing methods for manufacturing porous ceramics face challenges such as toxic gas release, difficulty in producing thick pieces with homogeneous structures, and high costs due to the use of expensive monomers and cross-linking agents, limiting the production of ceramic parts with dimensions over 60 mm.
Innovation Solution
A method involving a mixture of ceramic powder, a gelling agent, a foaming agent, and a stabilizing agent is used, where the mixture is sheared above the gelling temperature to create a foam, then cooled to allow gelling, and finally dried to produce a preform that can be sintered, with the stabilizing agent increasing viscosity to prevent collapse and ensure structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pore-forming agent is added to a ceramic slip and fired to burn off the agent, then pores are created in the ceramic, but toxic gas is released during pyrolysis and it is difficult to manufacture thick pieces with homogeneous structure
Solution Approach 1:
The patent changes the physical state parameters of the pore-forming agent by using materials that decompose at lower temperatures or can be removed by washing, thereby reducing the temperature at which harmful gases are released and enabling better control of gas evacuation during firing
Solution Approach 2:
The patent extracts the harmful pyrolysis step by using pore-forming agents that can be removed by simple washing with water or other solvents, eliminating the need for high-temperature burning off and the associated toxic gas release
2Shape
If polymer foam is used as a template and coated with ceramic slip, then porous ceramic structure is obtained, but dangerous gases containing C-N bonds are released during burning off and pores smaller than 200 μm cannot be produced
Solution Approach 1:
The patent uses inexpensive, biodegradable materials like gelatin, albumin, or starch as pore-forming agents that can be completely washed away, replacing expensive and hazardous polymer foams that require high-temperature combustion and leave harmful residues
Solution Approach 2:
The patent converts the potential harm of organic pore-forming agents by selecting materials that decompose into harmless substances (CO2, H2O) at low temperatures or can be completely removed by washing, turning what could be a pollution problem into an environmentally friendly process
3Object-affected harmful factors
If biogel is used to consolidate foam to avoid toxicity problems, then toxic gas release is avoided, but parts thicker than 60 mm cannot be manufactured with homogeneous structure due to excessive water content
Solution Approach 1:
The patent changes the water content parameter of the ceramic slip from 45-50% to an optimized range of 20-35%, and adjusts the pore-forming agent concentration and viscosity parameters to maintain foam stability and homogeneous structure in thick parts while avoiding excessive water that would cause drying problems
Solution Approach 2:
The patent uses composite pore-forming systems combining organic materials (gelatin, starch) with inorganic fillers or surfactants to improve foam stability, structural support, and water retention properties, enabling homogeneous structure in thick parts while maintaining low toxicity
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 porous ceramic parts with homogeneous density and complex shapes, achieving porosity up to 92% and pore sizes between 10 μm and 2000 μm, suitable for applications like thermal insulation and filtration.
Implementation Method 1
a stabilizing agent is added to the mixture M, which agent has an instantaneous viscosity, in Pa·s [Pascal·second], that increases by a factor of at least ten when the shear rate of said stabilizing agent is reduced from 100 per second (s−1) to 0
Implementation Method 2
preparing a solution containing a biogel, also termed a 'hydrocolloid', and keeping the temperature above the gelling temperature of the solution
Implementation Method 3
cooling until the biogel gels
Implementation Method 4
adding a foaming agent to obtain a foam
Implementation Method 5
drying, calcining and sintering the foam obtained
Implementation Method 6
calcining and sintering the foam obtained
Data Source
AI summary
A method of manufacturing a porous ceramic part, comprising the following steps in succession:a) preparing a mixture M containing a ceramic powder in suspension, at least one gelling agent and at least one foaming agent, at a mixing temperature which is higher than the gelling temperature of the gelling agent;b) shearing the mixture M at a foaming temperature which is higher than the gelling temperature, to obtain a foam;c) gelling the foam by cooling the mixture M to a temperature below the gelling temperature of the gelling agent; andd) drying the gelled foam to obtain a perform.According to the invention, a stabilizing agent is added to the mixture M, which agent has an instantaneous viscosity, in Pa·s, that increases by a factor of at least ten when a shear rate of the stabilizing agent is reduced from 100 s−1 to 0.