Heteroatom Polyol Ceramic Precursor Batches for High Tonset Extrusion
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Solution Overview
Problem
The formation of ceramic honeycombs faces limitations in extrusion feed rate due to the low stiffening onset temperature (Tonset) of ceramic precursor batches, leading to increased processing costs and potential distortions during drying and firing.
Innovation Solution
Incorporating a heteroatom polyol, such as thiodiethanol or 3,3′-thiodipropanol, into the ceramic precursor batch composition along with a cellulose-based binder and an aqueous solvent, which increases the Tonset, allowing for higher extrusion feed rates and reduced pressure, and providing antioxidant properties to prevent cracking during firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ceramic precursor batches are used, then the extrusion process can be performed, but the extrusion feed rate is limited due to low Tonset
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor batch by incorporating heteroatom polyols (containing S, N, or P atoms) alongside conventional cellulose-based binders. This compositional parameter change modifies the thermal-rheological behavior of the batch, specifically increasing the Tonset from conventional levels to above 50°C, thereby enabling higher extrusion feed rates without compromising green body strength.
Solution Approach 2:
The patent creates a composite binder system combining heteroatom polyols (such as thiodiethanol, 3,3'-thiodipropanol) with conventional cellulose-based binders (methylcellulose, hydroxypropylmethylcellulose). This composite material approach leverages the synergistic effects of different binder components to achieve both high Tonset and adequate green body strength, resolving the contradiction between productivity and temperature control.
2Productivity
If higher extrusion feed rates are attempted, then productivity increases, but processing costs increase and distortions may occur
Solution Approach 1:
By modifying the batch composition to include heteroatom polyols, the patent achieves a Tonset above 50°C, which creates an optimal rheological window for high-speed extrusion. This parameter change allows the process to operate at higher feed rates without requiring additional processing steps or equipment, thereby increasing productivity without proportionally increasing processing costs.
3Productivity
If higher extrusion feed rates are used, then productivity increases, but green body strength may be compromised leading to cracking
Solution Approach 1:
The composite binder system combining heteroatom polyols with cellulose-based binders provides both high Tonset (above 50°C) and adequate green body strength. The heteroatom polyols contribute to thermal stability and rheological control, while the cellulose-based binders provide binding strength and structural integrity, enabling high feed rates without compromising green body strength or causing cracking.
Solution Approach 2:
The heteroatom polyols serve as sacrificial additives that perform their function during the critical extrusion and drying phases (providing high Tonset and rheological control) but are designed to be completely removed during subsequent firing. This allows them to temporarily enhance green body strength and enable high-speed processing without leaving residual contaminants in the final ceramic product.
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 use of heteroatom polyols in ceramic precursor batches results in a higher Tonset, enabling increased extrusion feed rates, reduced pressure, and improved green body strength, with reduced chances of cracking and processing costs, while maintaining uniformity and integrity of the ceramic honeycombs.
Implementation Method 1
Tonset refers to the temperature at which the rheology of the batch begins to transition from low to high viscosity. Higher Tonset can enable greater batch feed rate
Implementation Method 2
cellulose ethers such as methylcellulose (MC), hydroxypropylcellulose (HPMC) and hydroxyethylmethylcellulose (HEMC) can form high temperature gels. The gelling behavior facilitates rapid drying while preventing distortions as they are heated
Implementation Method 3
providing antioxidant properties to prevent cracking during firing
Data Source
AI summary
A ceramic precursor batch composition comprising inorganic ceramic-forming ingredients, a binder, an aqueous solvent and a heteroatom polyol agent. The heteroatom polyol agent can be represented by X(R) where X is at least one of S, N, and P, and R is at least two of CH3, CH2CH2OH, CH2CH2CH2OH, CH2(CHOH)CH3, C(CH2OH)1-3, CH2OH, CH(CH2OH)CHOH, C(O)(CHOH)1-4CH2OH, and CH2CH2CH2OCH3. The presence of the heteroatom polyol agent provides a composition with a lower viscosity and/or a greater batch stiffening temperature (Tonset) allowing for increased rates of extrusion. Methods for producing a ceramic honeycomb body using this ceramic precursor batch composition are also provided.