Outer Periphery Coating Material for Honeycomb Structure
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Solution Overview
Problem
The existing honeycomb structures used for catalyst supports and filters face mechanical strength issues due to wall thinning and increased porosity, leading to cracking and breakage, especially when exposed to high temperatures, and have dimensional accuracy problems during manufacturing.
Innovation Solution
A ceramic outer periphery coating material comprising a mixture of cordierite particles, amorphous silica particles, and crystalline inorganic fibers, applied in a specific mass ratio and particle size distribution, to form a coated layer with improved mechanical strength and thermal expansion matching that of the honeycomb structure, reducing the likelihood of cracking at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If wall thinning and porosity increase are applied to reduce honeycomb structure weight, then temperature rising rate and catalyst activation improve, but mechanical strength decreases causing cracking and breakage
Solution Approach 1:
The patent applies composite materials by combining the honeycomb structure with an outer periphery coated layer comprising cordierite particles, amorphous silica particles, and crystalline inorganic fibers. This composite structure allows the base honeycomb to maintain thin walls and high porosity for weight reduction, while the coated layer provides enhanced mechanical strength and impact resistance to prevent cracking and breakage.
Solution Approach 2:
The patent applies local quality by providing reinforcement only in the outer peripheral portion of the honeycomb structure where it is most needed for impact resistance and handling strength. The outer periphery coated layer is applied specifically to this region rather than uniformly across the entire structure, allowing the central partition walls to remain thin and lightweight while the perimeter gains enhanced mechanical properties.
2Area of stationary object
If larger honeycomb diameter is manufactured for industrial applications, then application range expands, but shape stability and dimensional accuracy of partition walls deteriorate
Solution Approach 1:
The patent applies local quality by providing the outer periphery coated layer specifically on the outer peripheral surface of the honeycomb structure. This localized coating reinforces the outer edges and corners which are most susceptible to deformation during manufacturing and handling of large-diameter structures, thereby improving shape stability and dimensional accuracy without affecting the overall manufacturing process.
Solution Approach 2:
The patent applies preliminary action by forming the outer periphery coated layer before the honeycomb structure undergoes high-temperature firing or during the firing process itself. This pre-reinforcement ensures that the outer peripheral portion maintains its shape and dimensional accuracy throughout subsequent manufacturing steps and handling operations.
3Manufacturing precision
If conventional outer periphery coating is applied to improve shape accuracy and mechanical strength, then product quality improves, but thermal expansion mismatch causes cracking during heating/cooling cycles
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the composition parameters of the outer periphery coated layer, specifically the types and proportions of cordierite particles, amorphous silica particles, and crystalline inorganic fibers. These compositional adjustments enable the coated layer to achieve a coefficient of thermal expansion that closely matches the underlying honeycomb structure, thereby preventing cracking during thermal cycles while maintaining shape accuracy.
Solution Approach 2:
The patent applies composite materials by creating a multi-component coated layer system consisting of cordierite particles, amorphous silica particles, and crystalline inorganic fibers. This composite coating formulation allows for fine-tuning of thermal expansion properties to match the honeycomb substrate, while simultaneously providing the mechanical strength and shape stability needed for large-diameter structures.
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 solution effectively enhances the mechanical strength and thermal shock resistance of the honeycomb structure, preventing cracking at temperatures up to 800°C and maintaining dimensional accuracy, thus ensuring reliable performance in high-temperature applications.
Implementation Method 1
a thermal expansion behavior of the coated layer is different from that of the honeycomb structure
Data Source
AI summary
An outer periphery coating material being coated onto an outer peripheral surface of a ceramic honeycomb structure to form an outer periphery coated layer. The outer periphery coating material comprises: a particle mixture containing cordierite particles and amorphous silica particles in a mass ratio of from 40:60 to 80:20; and from 10 to 30% by mass of crystalline inorganic fibers in an outer percentage relative to the particle mixture. An average particle diameter of the cordierite particles is different from an average particle diameter of the amorphous silica particles.