SiC Honeycomb Structure with Lateral Electrodes
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Solution Overview
Problem
Conventional honeycomb structures with catalysts for exhaust gas purification face challenges such as insufficient initial catalyst temperature, excessive electric current flow with high voltage, and difficulty in loading catalysts due to metal heater limitations, requiring a solution that can function both as a catalyst carrier and heater with improved electrical resistance and structural integrity.
Innovation Solution
A honeycomb structure with a porosity of 30-60%, average pore size of 2-20 μm, and cell density of 50-150 cells/cm², incorporating lateral electrodes and an intermediate layer with materials like aluminum, molybdenum, tin, or zirconium to reduce electric resistance and enhance heat generation, while maintaining structural strength and catalyst loading efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal heater is used to raise exhaust gas temperature, then heating efficiency is improved, but electric resistance is too low causing excessive current flow that damages power source circuits
Solution Approach 1:
The invention changes the electrical parameter (resistance) of the heating element by using ceramic material with inherently higher resistance compared to metal, while maintaining the heating function. This allows the system to operate with high voltage power sources without excessive current flow.
Solution Approach 2:
The invention uses a composite structure combining ceramic heating elements with a honeycomb carrier, creating a unified component that provides both structural support and heating function with appropriate electrical resistance characteristics.
2Temperature
If a metal heater is machined to have a honeycomb structure, then heating function is improved, but catalyst loading becomes difficult and unitary joining is problematic
Solution Approach 1:
The invention merges the heater and catalyst carrier into a single integrated ceramic component, where the honeycomb structure serves both as the mechanical support for catalyst loading and as the heating element, eliminating the need for separate components and complex joining processes.
Solution Approach 2:
The ceramic honeycomb structure performs multiple functions simultaneously: it provides structural support for catalyst loading, generates heat through electrical resistance, and offers a high surface area for catalyst deposition, making it a universal component for both mechanical and thermal functions.
3Area of stationary object
If a honeycomb structure is designed with thin partition walls for high surface area, then catalyst loading capacity is improved, but structural strength decreases
Solution Approach 1:
The invention uses ceramic material with inherent high strength-to-weight ratio, allowing the partition walls to be thin enough to provide high surface area for catalyst loading while maintaining sufficient structural strength to support the catalyst and withstand operating conditions.
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 effectively generates heat uniformly, supports catalyst loading, and manages electric current flow, improving exhaust gas purification efficiency and reducing pressure loss, while being suitable for high voltage applications.
Implementation Method 1
the electric resistance of the interface between the honeycomb structural section and the electrode portion decreases to be able to suppress heat generation right under the electrode portion
Data Source
Figure 1~2
Figure 3~4B
Figure 5~6
AI summary
The aim is to provide a honeycomb structure having an electrode portion capable of being formed easily and functioning not only as a catalyst carrier but also as a heater. The honeycomb structure 100 is provided with a honeycomb structural section 4, a pair of lateral electrodes 23, 23 on the side face of the honeycomb structural section 4, and at least one intermediate layer 15 between the honeycomb structural section 4 and the lateral electrodes 23. The honeycomb structural section 4 has silicon carbide particles having an average particle diameter of 3 to 40 µm and silicon, and the ratio (Si/SiC) of silicon (Si) to silicon carbide (SiC) is 10/90 to 40/60. The lateral electrodes 23 have an average particle diameter of the silicon carbide particles of 20 to 150 µm and a Si/SiC ratio of 20/80 to 50/50. The intermediate layer 15 has an average particle diameter of silicon carbide particles and Si/SiC between those of the honeycomb structural section 4 and those of the lateral electrodes 23. The electric resistance between the lateral electrodes 23 of the honeycomb structural section 100 is 2 to 100Ω.