Cold-Set Ceramic Plug Composition for Honeycomb Bodies
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Solution Overview
Problem
Existing ceramic plug compositions for honeycomb bodies, particularly diesel particulate filters, face challenges with rheological behavior, leading to inadequate plug depth and increased voids and dimples due to particle size reduction and increased organic binder levels.
Innovation Solution
A cold-set plug composition comprising coarse cordierite particles, colloidal silica as an inorganic binder, and higher levels of organic binders like methylcellulose, which are not fired, achieving improved rheology and preventing voids and dimples by maintaining a coarser particle size distribution and optimal binder levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If particle size is decreased to improve flow in cement batch, then rheology improves, but voids and dimples in plug material increase
Solution Approach 1:
The patent changes the particle size distribution parameters by using a broader range of particle sizes (d10, d50, d90 specifications) rather than uniformly fine particles. This parameter change maintains favorable rheology through proper particle packing while reducing voids and dimples by eliminating the excessive fineness that causes syneresis and liquid separation.
Solution Approach 2:
The patent creates a composite particle size distribution system combining coarse, medium, and fine cordierite particles in specific proportions. This composite approach allows the mixture to exhibit both good flow characteristics (from finer particles filling gaps) and reduced defect formation (from coarser particles providing structural stability and reducing syneresis).
2Length of stationary object
If amounts of methylcellulose and water are increased to improve plug depth, then plug depth increases, but voids and dimples in plug material increase
Solution Approach 1:
The patent optimizes the binder content parameters by specifying precise ranges (0.5-3.0% organic binder, 20-60% liquid vehicle) rather than using excessive amounts. This parameter optimization achieves sufficient plug depth through improved particle packing and controlled rheology while avoiding the void formation associated with over-bonding and excessive liquid content.
Solution Approach 2:
The patent uses pre-reacted, ground cordierite powder as a model system that replicates the desired final product properties. By working with this pre-prepared material and optimizing its binder content, the patent achieves consistent plug depth and quality without the variability that leads to voids and dimples in less controlled formulations.
3Ease of operation
If organic binder is included to achieve favorable rheology, then plasticity improves, but firing temperature must be increased to remove organic components
Solution Approach 1:
The patent optimizes the organic binder concentration parameters to use lower levels (0.5-3.0%) compared to conventional formulations. This parameter reduction decreases the amount of organic material requiring combustion, thereby lowering the peak firing temperature needed to remove carbon and other organic components while still maintaining adequate plasticity for plugging operations.
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 composition achieves desired plug depths of 4 mm to 12 mm with reduced voids and dimples, maintaining integrity without the need for a firing step, enhancing the plug's mechanical and rheological properties.
Implementation Method 1
The aqueous composition comprises coarse cordierite particles, colloidal silica as an inorganic binder
Implementation Method 2
the rheological behavior of the composition which has been found to be prone to syneresis (that is, liquid separation from solids)
Implementation Method 3
batch liquids wick into the porous ceramic walls and the cement dries out
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Disclosed are ceramic honeycomb bodies comprising a fired ceramic honeycomb body having a plurality of cell channels; and an unfired composition comprising a refractory filler, an inorganic binder, and an organic binder, wherein the refractory filler comprises particles; and wherein the particles of the refractory filler have a d50 ranging from about 10 [micro]m to about 40 [micro]m. The composition is used in the form of a plug, wherein the plug has a depth in the cell channel ranging from about 4 mm to about 12 mm, and wherein the plug is substantially free of voids and/or dimples. Further, a method of making a cold-set plug for a ceramic honeycomb body is disclosed. The method comprises: preparing an aqueous composition comprising a refractory filler, an inorganic binder, and an organic binder; and forming a cold-set plug from the composition; wherein the composition is not fired before or after the cold-set plug is formed; wherein the refractory filler comprises particles; and wherein the particles of the refractory filler have a d5o ranging from about 10 [micro]m to about 40 [micro]m.