Ceramic Honeycomb Skin Coating for Catalyst Absorption Resistance
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Solution Overview
Problem
Ceramic honeycomb structures used in catalytic converters and diesel particulate filters face challenges in achieving high mechanical strength, low heat capacity, and minimizing pressure loss while maintaining porosity and low wall thickness, which are compromised by exposure to acidic catalytic substances and vibration.
Innovation Solution
A ceramic honeycomb structure skin coating formulation incorporating refractory ceramic fibers, viscosity modifiers, colloidal inorganic oxides, and secondary inorganic fibers, which forms a hard, acid- and alkali-resistant surface to prevent catalyst absorption and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high porosity and low wall thickness are used to achieve low heat capacity and minimized pressure loss, then thermal performance improves, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of a ceramic honeycomb structure with controlled porosity (40-60%) combined with a specifically formulated skin coating containing refractory ceramic fibers, inorganic binders, and viscosity modifiers. This composite approach allows the base structure to maintain low heat capacity through high porosity while the skin coating provides the necessary mechanical strength and surface integrity.
2Strength
If ceramic paste skin coating is applied to enhance mechanical strength and protect from vibration, then structural integrity improves, but cracking and degradation by acidic catalytic substances occurs
Solution Approach 1:
The patent modifies the skin coating formulation by carefully controlling the water-to-ceramic ratio (0.3-0.5), using specific inorganic binders with appropriate bonding characteristics, and incorporating viscosity modifiers to achieve optimal green strength and firing behavior. These parameter changes prevent cracking during drying and firing while maintaining resistance to acidic catalytic substances.
Solution Approach 2:
The patent uses a disposable organic binder that is completely burned out during the firing process, leaving no residue that could interfere with catalyst performance. This temporary organic component provides green strength during handling and drying but is intentionally designed to be consumed during manufacturing.
3Stability of the object's composition
If multiple smaller honeycomb structures are bonded together to support their own weight, then structural stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent divides the honeycomb structure into multiple smaller monoliths that are bonded together using a ceramic adhesive material. This segmentation allows each individual monolith to support its own weight effectively while the adhesive bonds create a unified structure. The skin coating is then applied to the exterior surface of the assembled structure to provide uniform protection and surface finish.
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 skin coating provides increased mechanical strength, resistance to cracking and degradation, and reduces catalyst usage, thereby improving the structural integrity and durability of ceramic honeycomb structures while minimizing production costs.
Implementation Method 1
during the drying stage, a non-absorbent, hard, dense, eggshell-like surface forms on the surface of the skin coating
Implementation Method 2
a mixture is formed of: ceramic fibers or biosoluble inorganic fibers; an inorganic binder
Implementation Method 3
a mixture is formed of: ceramic fibers or biosoluble inorganic fibers; an inorganic binder
Implementation Method 4
a viscosity modifier
Implementation Method 5
addition of a secondary fiber can minimize cracking of the skin coating during the drying and firing stages
Data Source
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AI summary
A porous ceramic (honeycomb) structure skin coating and a method of producing a porous ceramic structure skin coating which provides a hardshell, strong, acid- and alkali-resistant, chip-resistant ceramic honeycomb structure coating which resists pollution control catalyst from being absorbed into the skin coating.