Non-Stoichiometric Cordierite Ceramic for Particulate Filters
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Solution Overview
Problem
Existing ceramic honeycomb bodies for diesel and gasoline particulate filters face challenges in achieving high bulk porosity, narrow pore size distribution, and thermal shock resistance, which affect filtration efficiency and durability in harsh engine exhaust environments.
Innovation Solution
A porous ceramic body with a predominant non-stoichiometric cordierite phase and a composition of MgO, Al2O3, and SiO2 within specific weight percent ranges, optionally containing P2O5, is developed, featuring high average bulk porosity and a narrow pore size distribution, achieved through a manufacturing method involving specific inorganic ingredients, an organic binder, and a pore former, and then fired under controlled conditions to produce a material with enhanced thermal shock resistance and filtration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ceramic honeycomb bodies are used to achieve high bulk porosity, then filtration efficiency is improved, but thermal shock resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (MgO: 12.2-16.6 wt%, Al2O3: 31.1-34.1 wt%, SiO2: 50.5-55.5 wt%) and firing conditions to achieve non-stoichiometric cordierite phase formation. This compositional parameter optimization enables simultaneous achievement of high bulk porosity (≥50%) and narrow pore size distribution (df ≤0.50) while maintaining thermal shock resistance, resolving the contradiction between filtration efficiency and thermal stability.
Solution Approach 2:
The patent employs composite material principles by creating a multi-phase ceramic system comprising non-stoichiometric cordierite as the predominant phase (≥85 wt%) combined with controlled amounts of other crystalline phases. This composite structure, achieved through specific batch composition mixing and controlled firing, provides both the porosity needed for filtration and the structural integrity required for thermal shock resistance.
2Reliability
If conventional ceramic honeycomb bodies are used to achieve narrow pore size distribution, then gas flow permeability is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent utilizes parameter changes by optimizing the chemical composition parameters and firing temperature profile to achieve precise control over pore size distribution. The specific oxide ratios (MgO:Al2O3:SiO2 within defined ranges) and controlled firing conditions enable consistent formation of non-stoichiometric cordierite with narrow pore size distribution (df ≤0.50), achieving both high gas flow permeability and manufacturing precision.
Solution Approach 2:
The patent replaces mechanical pore formation methods with chemical phase formation mechanisms. Instead of relying solely on physical pore formers or mechanical processing, the invention uses controlled chemical reactions during firing to form non-stoichiometric cordierite phases that inherently provide the desired pore structure. This chemical mechanism substitution enables better control over pore size distribution and improves manufacturing precision.
3Reliability
If conventional ceramic honeycomb bodies are used to achieve high bulk porosity, then filtration efficiency is improved, but structural integrity deteriorates
Solution Approach 1:
The patent applies composite material principles by creating a multi-phase ceramic system where non-stoichiometric cordierite (≥85 wt%) forms the structural matrix, supplemented by controlled amounts of other crystalline phases. This composite structure provides both the high bulk porosity (≥50%) needed for filtration efficiency and the structural integrity to maintain shape and strength under thermal and mechanical stress.
Solution Approach 2:
The patent uses parameter changes by optimizing the chemical composition parameters and firing conditions to achieve the right balance between porosity and structural integrity. The specific oxide ratios and controlled firing temperature profile ensure that the non-stoichiometric cordierite phase forms with appropriate crystallinity and grain size, providing both filtration performance and structural strength.
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 resulting ceramic body exhibits superior gas flow permeability, washcoat compatibility, and filtration efficiency, while maintaining structural integrity and thermal stability, thus improving fuel economy and reducing emissions.
Implementation Method 1
the exhaust gas flows through porous walls of the ceramic honeycomb body of the particulate filter. Along its flow path through the porous walls, particulates from the exhaust gas are retained by the honeycomb body
Implementation Method 2
fired under conditions effective to convert the green body into the porous ceramic body comprising a combined weight percentage of at least 85 wt% of crystalline phases containing cordierite and indialite
Data Source
Figure 1A~1C
Figure 2~3
Figure 4A~4B
AI summary
A cordierite-containing ceramic body with %P ≥ 50%, df ≤ 0.50, and a combined weight percentage of crystalline phases containing cordierite and indialite of at least 85 wt%. The porous ceramic body contains, as expressed on a relative oxide weight percent basis in terms of MgO, Al2O3, and SiO2 that is within a field defined by (15.4, 34.1, and 50.5), (12.2, 34.1, and 53.7), (13.3, 31.2, and 55.5), and (16.6, 31.1, and 52.3). Batch composition mixtures and methods of manufacturing a porous ceramic body using the batch compositions are provided, as are other aspects.