Honeycomb Structure Joining Material Layer Heat Shock Resistance
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Solution Overview
Problem
There is a growing demand for enhanced heat shock resistance in honeycomb structure bodies used as diesel particulate filters, as increased heat stress during regeneration leads to defects such as cracks and breakdowns, necessitating improved stress relaxing and joining strength in the joining material layers.
Innovation Solution
A honeycomb structure body with joining material layers composed of three layers at a thickness ratio of 1:2:1, with a porosity of 45-75% and containing materials like silicon carbide, cordierite, alumina, zirconia, or yttria, where the ratio of spherical pores is 60% or more, providing a stress relaxing function compatible with joining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the filter size is enlarged to meet increasing demand, then the filtering capacity is improved, but the heat stress during regeneration increases leading to cracks and breakdowns
Solution Approach 1:
The filter is divided into multiple honeycomb segments that are joined together, allowing heat stress to be distributed and relaxed at the joining material layers between segments, preventing cracks while maintaining large filtering capacity
Solution Approach 2:
The joining material layers are designed with controlled porosity (40-80%) and specific pore structures, enabling them to absorb and relax heat stress through the porous network while maintaining structural integrity under thermal conditions
2Object-affected harmful factors
If the joining material layer has high porosity to relax heat stress, then the stress relaxing function is improved, but the joining strength decreases
Solution Approach 1:
The joining material layer has non-uniform pore distribution with different pore sizes and densities at different locations - higher porosity near honeycomb segments for stress relaxation, and optimized density in the middle for maintaining joining strength
Solution Approach 2:
The joining material layer is composed of multiple materials including ceramic particles, binders, and pore-forming agents, creating a composite structure that simultaneously provides stress relaxation through porosity and sufficient joining strength through material composition
3Strength
If the joining material layer has high joining strength to connect segments, then the structural integrity is improved, but the stress relaxing function decreases leading to heat shock resistance problems
Solution Approach 1:
The joining material layer incorporates a controlled porous structure with porosity of 40-80%, allowing the material to flex and relax thermal stresses while maintaining sufficient mechanical strength to join segments together
Solution Approach 2:
The pore size distribution is specifically controlled with average pore diameters of 10-100 μm and aspect ratios of 0.5-2.0, optimizing the balance between stress relaxation capability and structural strength for heat shock resistance
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 honeycomb structure body achieves excellent heat shock resistance, preventing cracks and maintaining performance even under high heat stress, with a compressive Young's modulus of 15-80 MPa and bending strength of 0.8-3.0 MPa, surpassing conventional structures.
Implementation Method 1
a joining material layer which integrally joins a plurality of honeycomb segments and has an excellent stress relaxing function
Implementation Method 2
the exhaust gas passes through the porous partition wall... a large heat stress takes place in the filter
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
There is disclosed a honeycomb structure body having joining material layers of a stress relaxing function and joining strength equivalent to those of joining material layers of a conventional honeycomb structure body, and having an excellent heat shock resistance. A honeycomb structure body 100 includes a plurality of honeycomb segments 4 having porous partition walls with which a plurality of cells extending from one end surface to the other end surface to become through channels of a fluid are formed, and an outer peripheral wall positioned at the outermost periphery and disposed to surround the partition walls, and having plugged portions arranged in one end portion of each of predetermined cells and the other end portion of each of the remaining cells; and joining material layers 13 having a plurality of pores and joining the plurality of honeycomb segments 4 in a state where the honeycomb segments 4 are arranged adjacent to each other so that side surfaces of the honeycomb segments face each other. A ratio of the number of pores having a value of 1.2 or less which is obtained by dividing a maximum diameter of each of the pores by a minimum diameter of the each of the pores is 60% or more of the number of all the pores of each of the joining material layers 13.