Ceramic Honeycomb Filter Plug Bonding via Dielectric Heating
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Solution Overview
Problem
Ceramic honeycomb filters face issues with plug detachment due to insufficient bonding strength between plugs and cell walls, especially when used as catalyst-carrying filters, leading to reduced particulate-matter-capturing performance and heat shock resistance.
Innovation Solution
The use of microwave or high-frequency dielectric heating to uniformly dry the plugging material, ensuring consistent colloidal oxide concentration and strong bonding between plugs and cell walls, with a plugging material comprising ceramic particles and an amorphous oxide matrix, and a specific particle size distribution for the ceramic particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plugs are formed by sintering cordierite-forming material at high temperature (1300°C or higher), then complete plugging of flow paths is achieved, but large residual stress is generated causing cracking and plug peeling
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (1300°C or higher) to a lower temperature range (1000-1200°C). This parameter change reduces thermal stress and prevents cracking while maintaining effective plugging through optimized plugging material composition containing cordierite-forming powder, silica powder, and alumina powder in specific ratios
Solution Approach 2:
The patent uses a composite plugging material consisting of cordierite-forming powder (50-80 wt%), silica powder (10-30 wt%), and alumina powder (5-20 wt%). This composite formulation achieves complete plugging at lower sintering temperatures while maintaining bonding strength and reducing residual stress compared to pure cordierite materials
2Ease of manufacture
If plugs are made from material with different thermal expansion coefficient than honeycomb structure, then manufacturing is easier, but thermal expansion difference causes cracking under high-temperature conditions
Solution Approach 1:
The patent achieves homogeneity in thermal expansion characteristics by formulating the plugging material with cordierite-forming powder as the main component (50-80 wt%), which has a thermal expansion coefficient matching the cordierite honeycomb structure. This material composition homogeneity prevents differential thermal expansion cracking while maintaining manufacturing simplicity
Solution Approach 2:
The patent modifies the chemical composition parameters of the plugging material to match the thermal expansion properties of the honeycomb structure. By controlling the ratios of cordierite-forming powder, silica, and alumina, the plugging material achieves thermal expansion compatibility with the cordierite substrate, eliminating cracking under thermal shock
3Strength
If high sintering temperature (1400°C) is used to form plugs, then plug material bonds strongly to structure, but production cost increases and residual stress causes cracking
Solution Approach 1:
The patent reduces the sintering temperature parameter from 1400°C to 1000-1200°C by optimizing the plugging material composition. The inclusion of silica powder and alumina powder alongside cordierite-forming powder enables effective bonding at lower temperatures, reducing energy consumption and production costs while maintaining adequate bonding strength
Solution Approach 2:
The patent employs a composite plugging material formulation that achieves strong bonding at reduced sintering temperatures. The combination of cordierite-forming powder (50-80 wt%), silica powder (10-30 wt%), and alumina powder (5-20 wt%) creates a eutectic system that bonds effectively at 1000-1200°C, significantly lowering production costs compared to conventional 1400°C sintering
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 method achieves high bonding strength between plugs and cell walls, reducing plug detachment and maintaining particulate-matter-capturing performance while providing excellent heat shock resistance and cost-effective production.
Implementation Method 1
The plugging material is subjected to microwave heating or high-frequency dielectric heating
Implementation Method 2
The plugging material is subjected to microwave heating or high-frequency dielectric heating
Implementation Method 3
the plugs comprising ceramic particles and an amorphous oxide matrix existing between the ceramic particles
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 2(c)~4
AI summary
A ceramic honeycomb filter comprising a ceramic honeycomb structure having pluralities of flow paths partitioned by porous cordierite cell walls, and plugs formed in predetermined flow paths of the ceramic honeycomb structure; the plugs being formed by ceramic particles and an amorphous oxide matrix existing between the ceramic particles; in a cross section of the plugs, an area ratio A1 of the amorphous oxide matrix in a longitudinal range of 1/3 x t from one end, and an area ratio A2 of the amorphous oxide matrix in a longitudinal range of 1/3 x t from the other end meeting the relation of 2/3 ≤ A1/A2 ≤ 2, wherein t represents the length of the plug in a direction perpendicular to the longitudinal direction of the plug.