SiC Honeycomb Electrode Resistivity and Heat Uniformity
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Solution Overview
Problem
Conventional honeycomb structures used as both catalyst carriers and heaters experience temperature unevenness due to high electrical resistivity of electrode sections, leading to inadequate heat distribution during heat generation.
Innovation Solution
A honeycomb structure with a tubular design and band-shaped electrode sections made of silicon carbide with low stacking faults, bound by a metal silicide and silicon binding material, which reduces electrical resistivity and enhances even current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrode sections are used in the honeycomb structure, then the structure can function as a heater, but temperature unevenness occurs due to high electrical resistivity
Solution Approach 1:
The patent changes the electrical resistivity parameter of the electrode sections by using silicon carbide particles with specific characteristics (average particle diameter of 10 to 70 μm, Si/SiC mass ratio of 20/80 to 50/50) to achieve both low resistivity and uniform heat distribution
Solution Approach 2:
The electrode sections are constructed as composite materials containing both silicon and silicon carbide, where silicon acts as the binding material and silicon carbide provides electrical conductivity, creating a material that simultaneously achieves low electrical resistivity and uniform heat generation
2Power
If electrode sections with high electrical resistivity are used, then heat generation is sufficient, but current flow becomes uneven creating temperature unevenness
Solution Approach 1:
The patent optimizes the electrical resistivity parameter of the electrode sections to a specific range (volume electrical resistivity at 400°C of 0.01 to 0.4 Ωcm) to achieve both sufficient heat generation and uniform current distribution throughout the honeycomb structure
3Temperature
If the electrode sections are made thinner to improve current distribution, then temperature unevenness decreases, but the structural integrity may be compromised
Solution Approach 1:
The electrode sections use a composite structure with silicon carbide particles bound by silicon, creating a material that maintains structural integrity even when made thinner, as the silicon binding material provides mechanical strength while the silicon carbide particles provide electrical conductivity
Solution Approach 2:
The electrode sections have a porous structure with controlled porosity that allows for thin profiles while maintaining sufficient mechanical strength, enabling uniform current distribution without compromising 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
The solution effectively lowers the electrical resistivity of the electrode sections, ensuring even heat generation across the honeycomb structure, thereby reducing temperature unevenness and improving heat distribution.
Implementation Method 1
a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto
Implementation Method 2
an electrical resistivity of the electrode sections is from 0.01 to 0.4 Ωcm
Implementation Method 3
the binding material constituting the electrode section contains silicon and a metal silicide
Data Source
AI summary
A honeycomb structure includes a tubular honeycomb structure body having porous partition walls to define and form a plurality of cells, and an outer peripheral wall; and a pair of electrode sections disposed on a side surface of the honeycomb structure body, an electrical resistivity of the honeycomb structure body is from 1 to 200 Ωcm, each of the pair of electrode sections is formed into a band shape extending in an extending direction of the cells, the electrode section is constituted of a porous body in which particles made of silicon carbide as an aggregate are bound by a binding material, silicon carbide as the aggregate constituting the electrode sections contains β-SiC having a stacking fault of 2% or less, and the binding material constituting the electrode sections contains silicon and a metal silicide.