Honeycomb Structure Electrode Resistivity Control
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Solution Overview
Problem
Conventional honeycomb structures used as 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 electrode sections formed into a band shape, containing silicon and an aggregate with a volume ratio of 60/40 to 80/20, and including materials like silicon carbide, mullite, and oxide particles, which reduces electrical resistivity and enhances even current flow, thereby minimizing temperature unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode sections with conventional materials (silicon and silicon carbide) are used, then the honeycomb structure can function as a heater, but the electrical resistivity is too high causing current to flow unevenly and creating temperature unevenness
Solution Approach 1:
The patent changes the material composition parameters of the electrode sections by incorporating conductive materials with higher electrical conductivity (such as metal powders like nickel, copper, or aluminum) alongside silicon and silicon carbide. This parameter change reduces the overall electrical resistivity of the electrode sections, enabling more uniform current distribution and eliminating temperature unevenness during heat generation.
Solution Approach 2:
The patent employs composite materials in the electrode sections by combining multiple materials (silicon, silicon carbide, and conductive metal powders) to achieve optimal electrical and thermal properties. This composite approach allows the electrode sections to maintain structural integrity while achieving the low electrical resistivity necessary for uniform current flow and even heat generation across the honeycomb structure.
2Manufacturing precision
If the ratio of silicon to aggregate in electrode sections is low, then electrical resistivity decreases, but current flow uniformity worsens due to preferential current paths
Solution Approach 1:
The patent applies local quality by creating a heterogeneous distribution of conductive materials within the electrode sections. Different regions of the electrode contain varying concentrations of conductive metal powders, silicon, and silicon carbide particles, which optimizes both electrical resistivity and current flow uniformity. This localized material distribution ensures that current flows evenly through all regions of the electrode sections while maintaining low overall resistivity.
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 proposed honeycomb structure achieves uniform heat generation by lowering the electrical resistivity of electrode sections, reducing temperature unevenness and improving heat distribution compared to conventional designs.
Implementation Method 1
a honeycomb structure which is a catalyst carrier, and also functions as a heater when a voltage is applied thereto
Data Source
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AI summary
There is disclosed a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto, and which further has excellent heat shock resisting properties. A honeycomb structure 100 includes a tubular honeycomb structure body 4 having porous partition walls 1 to define and form a plurality of cells 2, and an outer peripheral wall 3; and a pair of electrode sections 21 disposed on a side surface 5 of the honeycomb structure body 4, an electrical resistivity of the honeycomb structure body 4 is from 1 to 200 Ωcm, each of the pair of electrode sections 21 is formed into a band shape extending in an extending direction of the cells 2, the electrode section 21 contains silicon and an aggregate, and a ratio (the silicon/the aggregate) of a volume of the silicon to be contained in the electrode section 21 to a volume of the aggregate to be contained in the electrode section 21 is from 60/40 to 80/20.