Electrically Heated Honeycomb Support to Slow Oxide Growth
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Solution Overview
Problem
Existing electrically heating supports experience rapid resistance increase due to oxide film growth in high-temperature environments, leading to prolonged heating times and inefficient temperature rise.
Innovation Solution
The honeycomb structure is made of a ceramic porous body with a specific surface area of 0.01 m²/g to 0.20 m²/g and a volume ratio of silicon metal of 18 vol% or more, reducing the area exposed to air and slowing resistance increase while maintaining efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electrically heating support is used in a high-temperature environment, then the catalyst can be activated to purify exhaust gas, but the resistance increases due to oxide film growth on the conductive path
Solution Approach 1:
The patent applies porous ceramic materials with controlled pore structures to the honeycomb support. The porous structure provides a large surface area for catalyst support while the controlled pore size and distribution minimize oxide film formation on conductive paths. Specifically, the ceramic porous body has porosity of 30-50% with pore diameters of 1-10 μm, which reduces the contact area between oxygen and the conductive path, thereby slowing resistance increase while maintaining high-temperature catalytic activation.
Solution Approach 2:
The patent uses composite materials combining ceramic porous body with conductive components. The ceramic porous body serves as both structural support and catalyst carrier, while conductive additives or coatings are incorporated to maintain electrical conductivity. This composite approach allows the material to simultaneously provide mechanical strength, catalytic activity, and stable electrical conductivity at high temperatures, resolving the contradiction between temperature activation and resistance stability.
2Temperature
If the conductive path is exposed to air in high-temperature environment, then oxidation occurs forming oxide film, but the conductive path narrows and resistance increases
Solution Approach 1:
The patent creates an inert or low-oxygen environment around the conductive path by using ceramic materials with low oxygen permeability. The ceramic porous body acts as a barrier that limits oxygen diffusion to the conductive paths embedded within it. This passive protection mechanism reduces oxide film growth without requiring active atmosphere control, allowing high-temperature operation while minimizing oxidation of the conductive paths.
Solution Approach 2:
The ceramic porous body serves as an intermediary between the conductive path and the external air environment. It provides physical separation and selective permeability, allowing heat and catalyst access while blocking direct oxygen contact with the conductive path. This intermediary structure enables the system to maintain high temperatures for catalysis while protecting the electrical components from oxidative degradation.
3Loss of time
If the resistance increases rapidly, then the heating time extends beyond predetermined period, but the catalyst activation is delayed
Solution Approach 1:
The patent implements preliminary protective measures during manufacturing by embedding the conductive paths deep within the ceramic porous body structure before operation. The ceramic material is formed with controlled porosity and density to pre-establish a protective barrier against oxidation. This preliminary structuring prevents rapid oxide film formation during initial high-temperature operation, ensuring that resistance remains stable within the predetermined time period for catalyst activation.
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 configuration minimizes oxide film growth, ensuring a slower resistance increase and shorter heating times, thus achieving faster and more reliable temperature activation of the catalyst.
Implementation Method 1
heating the honeycomb structure itself by electrical conduction to increase a temperature of a catalyst supported on the honeycomb structure
Implementation Method 2
heating the honeycomb structure itself by electrical conduction
Implementation Method 3
the conductive path coming into contact with the air in the high-temperature environment, thereby causing an oxide film to grow on the surface of the conductive path
Data Source
Figure 1
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AI summary
An electrically heating support includes: a honeycomb structure 1 including a honeycomb structure portion 10 having an outer peripheral wall 100 and a partition wall 101 disposed on an inner side of the outer peripheral wall 100, the partition wall 101 defining a plurality of cells 102 each extending from one end face to other end face to form a flow path; and a pair of electrodes for applying a voltage to the honeycomb structure 1. The outer peripheral wall 100 and the partition wall 101 are made of a ceramic porous body, and the ceramic porous body has a specific surface area of 0.01 m2/g or more and 0.20 m2/g or less.