Ceramic Honeycomb Bonding Layer for Thermal Stress and Strength
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Solution Overview
Problem
Conventional ceramic honeycomb structures face issues with insufficient bonding material layer strength and thermal stress resistance during regeneration, leading to potential failure due to uneven heating, local heat generation, and rapid temperature changes.
Innovation Solution
A ceramic honeycomb structure with honeycomb segments bonded via a bonding material layer comprising silicon carbide particles and a bonding phase of cordierite and spinel phases, with a specific molar ratio and content, providing enhanced thermal-stress-relaxing function and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding material layer is provided between honeycomb segments to alleviate thermal stress, then thermal stress resistance is improved, but bonding material layer strength becomes insufficient
Solution Approach 1:
The bonding material layer is formed as a composite material comprising inorganic fibers (aluminosilicate fibers), inorganic binder (colloidal silica), inorganic particles (silicon carbide), and water. This composite structure provides both thermal stress resistance through the flexible fiber network and sufficient bonding strength through the binder matrix, resolving the contradiction between these two requirements.
Solution Approach 2:
The bonding material layer is designed with specific local properties: inorganic fibers provide thermal stress relaxation in regions experiencing temperature gradients, while inorganic particles enhance local bonding strength. The heterogeneous composition allows different regions of the bonding material to fulfill different functions, simultaneously achieving thermal stress resistance and bonding strength.
2Stability of the object's composition
If honeycomb segments are integrally bonded to form a ceramic honeycomb structure, then structural integrity is improved, but thermal shock resistance deteriorates due to rapid temperature change
Solution Approach 1:
The bonding material layer changes the thermal parameters of the overall structure by introducing materials with different thermal expansion coefficients and heat conductivity. The inorganic fibers and binder create a gradient structure that gradually transitions thermal stress, allowing the integrally bonded structure to maintain both structural integrity and thermal shock resistance.
Solution Approach 2:
The bonding material layer acts as an intermediary between adjacent honeycomb segments, mediating the transmission of thermal stress. The flexible inorganic fiber network absorbs and distributes thermal shocks, preventing direct stress transmission between rigid ceramic segments while maintaining structural integrity through bonding.
3Ease of manufacture
If conventional bonding materials are used to bond honeycomb segments, then ease of manufacture is improved, but heat conduction and bonding strength become insufficient under severe thermal conditions
Solution Approach 1:
The bonding material layer is designed with a porous structure formed by the network of inorganic fibers and distributed inorganic particles. This porous configuration maintains ease of manufacture through simple slurry application while providing enhanced heat conduction pathways through the silicon carbide particles and improved bonding strength through the fiber-reinforced matrix.
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 structure exhibits excellent thermal-stress-relaxing function and strength, comparable to or exceeding conventional structures, even under severe thermal conditions, with improved bonding strength and heat conduction.
Implementation Method 1
the bonding material layer comprising silicon carbide particles as aggregate and a bonding phase bonding the silicon carbide particles... providing enhanced thermal-stress-relaxing function and strength... with improved bonding strength and heat conduction
Implementation Method 2
a bonding phase bonding the silicon carbide particles... the bonding phase comprising at least a cordierite phase and a spinel phase
Data Source
AI summary
A ceramic honeycomb structure comprising pluralities of honeycomb segments each having pluralities of longitudinally penetrating flow paths partitioned by porous cell walls and plugs formed in the end portions of the flow paths, and a bonding material layer boding the peripheral walls of the honeycomb segments, the bonding material layer comprising silicon carbide particles as aggregate and a bonding phase bonding the silicon carbide particles, the bonding phase comprising at least a cordierite phase and a spinel phase, the molar ratio M1 of the cordierite phase [=cordierite phase/(cordierite phase+spinel phase)] being 0.50 or more and less than 1.0, and the content of (cordierite phase+spinel phase) in the bonding phase being 50% or more by mass.