Pre-Reacted Pseudobrookite Batch Mixtures for Low-CTE Ceramic Honeycombs
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Solution Overview
Problem
Conventional ceramic honeycomb bodies with high porosity experience high coefficients of thermal expansion (CTEs), leading to cracking during thermal cycles due to lower thermal capacity and higher porosity, which affects durability and increases back pressure.
Innovation Solution
A batch mixture comprising pre-reacted pseudobrookite particles consisting of aluminum titanate and magnesium dititanate, combined with reactive alumina, titania, and silica sources, is used to form honeycomb bodies with reduced CTEs, enhancing thermal durability and lowering back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high porosity is used in ceramic honeycomb bodies, then flow-through capability and filtration efficiency are improved, but thermal capacity decreases and CTE increases leading to cracking during thermal cycles
Solution Approach 1:
The patent changes the chemical composition parameters of the ceramic body by incorporating pre-reacted pseudobrookite particles (aluminum titanate and magnesium dititanate) into the batch mixture. This compositional parameter change results in reduced CTE while maintaining high porosity, thereby improving thermal stability without sacrificing filtration efficiency
Solution Approach 2:
The patent creates a composite ceramic material by combining pre-reacted pseudobrookite particles with reactive alumina, titania, and silica sources. This composite approach leverages the low CTE properties of pseudobrookite to stabilize the overall thermal expansion behavior of the honeycomb body while preserving its porous structure for effective filtration
2Productivity
If high porosity is used in ceramic honeycomb bodies, then flow-through capability is improved, but thermal capacity decreases leading to higher CTE and cracking
Solution Approach 1:
The patent modifies the thermal parameters of the ceramic material by introducing pre-reacted pseudobrookite particles that have distinct thermal properties. This parameter change reduces the overall CTE and improves thermal capacity retention even in high porosity structures, allowing the body to withstand thermal cycles without cracking while maintaining flow-through capability
3Ease of manufacture
If conventional batch mixtures are used, then manufacturing simplicity is maintained, but CTE remains high leading to cracking and reduced durability
Solution Approach 1:
The patent applies preliminary action by pre-reacting the pseudobrookite particles before incorporating them into the batch mixture. This pre-reaction step prepares the particles with stable, low CTE properties that will persist through subsequent manufacturing and firing processes, ensuring durability without complicating the overall manufacturing approach
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 honeycomb bodies exhibit low CTEs, improving thermal stability and reducing back pressure, while maintaining high porosity, thus enhancing durability and efficiency in applications like catalytic converters and particulate filters.
Implementation Method 1
conventional ceramic honeycomb bodies with high porosity experience high coefficients of thermal expansion (CTEs)... The honeycomb bodies exhibit low CTEs, improving thermal stability
Implementation Method 2
heating the green ceramic body at the one or more reactive sintering temperatures and for one or more times sufficient to cause the reactive alumina source, the reactive titania source, and the reactive silica source to reactively sinter
Data Source
AI summary
A batch mixture comprising pre-reacted pseudobrookite particles consisting essentially of aluminum titanate and magnesium dititanate, a reactive alumina source, a reactive titania source, and a reactive silica source. Other batch mixtures and methods of manufacturing honeycomb extrudates and porous honeycomb bodies using the batch mixture are disclosed.