Honeycomb Structure Crack Prevention via Slit-Separated Electrodes
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Solution Overview
Problem
Honeycomb structures used in electrically heating catalysts are prone to vertical cracks due to temperature differences caused by uneven thermal expansion, which can disrupt the electric conduction path and lead to structural failure.
Innovation Solution
A honeycomb structure design featuring ceramic materials with electrode layers and reinforcing layers on the outer surface, where the reinforcing layers are electrically separated from the electrode layers by slits, providing additional structural support and uniform heating while preventing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the honeycomb structure is heated by electric conduction, then the catalyst temperature increases to activation temperature, but temperature difference between central and outer peripheral portions causes vertical cracks
Solution Approach 1:
The patent applies thermal expansion principles by designing the honeycomb structure with specific thermal properties. The ceramic material and its configuration are selected to manage thermal expansion differences between the central and outer peripheral portions during heating, thereby reducing thermal stress that would otherwise cause vertical cracks while maintaining effective catalyst activation temperature.
Solution Approach 2:
The patent employs composite material structure combining ceramic honeycomb walls with coated catalyst layers. This composite design allows the base ceramic structure to provide thermal stability and crack resistance, while the catalyst coating layer enables effective catalytic activity at activation temperature, thus resolving the contradiction between heating effectiveness and structural integrity.
2Use of energy by moving object
If the honeycomb structure uses conductive ceramics for electric heating, then the structure can be heated by electric conduction, but the structure becomes prone to cracking under thermal stress
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the electrical conductivity and thermal conductivity parameters of the ceramic material. The ceramic is designed to have sufficient electrical conductivity for effective Joule heating while maintaining appropriate thermal conductivity to distribute heat evenly, and its mechanical parameters are optimized to resist thermal stress-induced cracking.
Solution Approach 2:
The patent addresses the reliability issue by designing the ceramic honeycomb structure with controlled thermal expansion characteristics. The material composition and microstructure are engineered to minimize differential thermal expansion between different regions of the honeycomb during heating cycles, thereby preventing crack formation and maintaining structural reliability under repeated thermal stress.
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 design effectively suppresses the generation of vertical cracks, ensures uniform heating, and enhances the structural integrity of the honeycomb structure, maintaining the electric conduction path and preventing structural failure.
Implementation Method 1
heat the honeycomb structure itself by electric conduction to increase a temperature of a catalyst supported on the honeycomb structure
Implementation Method 2
heat the honeycomb structure itself by electric conduction to increase a temperature
Implementation Method 3
stress that induces cracks extending in the axial direction (vertical cracks) in the outer peripheral portion is generated in the honeycomb structure due to a difference in thermal expansion of the honeycomb structure
Data Source
AI summary
A honeycomb structure includes: a honeycomb structure portion 1 made of ceramics, the honeycomb structure portion 1 including an outer peripheral wall 10, a partition wall 11defining a plurality of cells 11a, and a plurality of slits 12 cut inwardly in a radial direction from the outer peripheral wall 10; a pair of electrode layers 2 being provided on an outer surface of the outer peripheral wall 10 so as to face each other across a central axis CA of the honeycomb structure portion 1; and reinforcing layers 3 provided on the outer surface of the outer peripheral wall 10 so as to be located between the pair of electrode layers 2 in a circumferential direction 1C of the honeycomb structure portion 1, the reinforcing layers 3 being electrically separated from the pair of electrode layers 2 by the slits 12.