Ceramic Honeycomb Peripheral Wall Adhesion
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Solution Overview
Problem
Ceramic honeycomb structures with high-porosity cell walls face challenges in achieving sufficient isostatic strength and preventing peripheral wall detachment during heat shock, as existing methods fail to provide adequate reinforcement and adhesion.
Innovation Solution
The method involves applying colloidal metal oxide followed by a coating material with ceramic aggregate to the peripheral surface of the ceramic honeycomb body, forming a peripheral wall that effectively clogs pores and enhances bonding strength between the cell walls and the peripheral wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cell walls have high porosity (50% or more) to increase catalyst capacity, then NOx-cleaning capacity is improved, but isostatic strength and heat shock resistance deteriorate
Solution Approach 1:
The invention applies different porosity characteristics to different regions: the inner cell walls maintain high porosity (50% or more) for catalyst capacity, while the peripheral cell walls have reduced porosity to provide structural strength. This local differentiation allows the structure to simultaneously achieve high catalyst capacity and sufficient mechanical strength.
Solution Approach 2:
The peripheral wall is formed as a composite structure combining ceramic particles and binder, creating a material with different properties from the high-porosity cell walls. This composite peripheral wall provides the necessary mechanical strength and heat shock resistance while allowing the inner high-porosity regions to maintain catalyst capacity.
2Strength
If a peripheral wall is formed by coating material to reinforce strength, then isostatic strength is improved, but the peripheral wall detaches under heat shock
Solution Approach 1:
The invention changes the porosity parameter of the peripheral cell walls compared to the inner cell walls. By reducing porosity in the peripheral region, the structure achieves both strength enhancement and heat shock resistance, preventing peripheral wall detachment while maintaining catalyst capacity in the inner regions.
3Reliability
If stress-releasing portions are added to prevent crack propagation, then heat shock resistance is improved, but peripheral wall detachability increases
Solution Approach 1:
The invention applies local quality differentiation by creating peripheral cell walls with different porosity characteristics from the inner cell walls. This local modification provides crack propagation resistance and maintains peripheral wall adhesion without requiring stress-releasing portions that would compromise structural integrity.
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 approach results in a ceramic honeycomb structure with high isostatic strength and improved heat shock resistance, preventing peripheral wall detachment even at high porosity levels, thus ensuring durability and performance under heat stress.
Implementation Method 1
effectively clogs pores and enhances bonding strength between the cell walls and the peripheral wall
Implementation Method 2
enhances bonding strength between the cell walls and the peripheral wall
Data Source
Figure 1(a)~2(a)
Figure 2(b)~3(b)
Figure 4(a)~5
AI summary
A method for producing a ceramic honeycomb structure comprising a ceramic honeycomb body having large numbers of longitudinal cells partitioned by porous cell walls having porosity of 50% or more, and a peripheral wall formed on a peripheral surface of the ceramic honeycomb body, comprising the steps of extruding moldable ceramic material to form a honeycomb-structured ceramic green body; machining a peripheral portion of the green body or a sintered body obtained from the green body to remove part of cell walls in the peripheral portion to obtain a ceramic honeycomb body having longitudinal grooves on a peripheral surface; applying colloidal metal oxide to a peripheral surface of the ceramic honeycomb body and drying it, and then applying a coating material comprising ceramic aggregate having an average particle size of 1 µm or more to form the peripheral wall.