Ceramic Honeycomb Outer Wall Gradient Hardness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large ceramic honeycomb structures used in diesel engines and construction machines face issues with deformation, insufficient strength, and poor heat shock resistance due to deformation of cell walls near the outer peripheral wall, and existing coatings provide either insufficient hardness or heat shock resistance when subjected to vibration and shock.
Innovation Solution
A ceramic honeycomb structure with an outer peripheral wall formed by coating longitudinally extending grooves on the honeycomb body with a material containing cordierite particles and colloidal silica, where the hardness decreases from the outer peripheral portion to the inside portion, providing balanced hardness and heat shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer peripheral wall is made with high hardness coating material, then the hardness and damage resistance are improved, but the heat shock resistance deteriorates
Solution Approach 1:
The patent applies different hardness characteristics to different regions of the outer peripheral wall. The coating material is designed to have higher hardness in the outer peripheral portion (near the outer surface) and lower hardness in the inside portion (near the groove), creating a gradient structure that provides both damage resistance and heat shock resistance appropriate for each location.
Solution Approach 2:
The patent changes the physical parameters of the coating material by controlling the particle size distribution of ceramic particles. By using a mixture of fine particles (0.1-10 μm) and coarse particles (10-50 μm) in specific proportions, and controlling the colloidal silica content (5-25 parts by mass per 100 parts cordierite particles), the material achieves different hardness levels in different regions during the drying process.
2Ease of manufacture
If the outer peripheral wall is made with uniform hardness, then the manufacturing simplicity is improved, but the heat shock resistance deteriorates
Solution Approach 1:
The patent creates non-uniform hardness distribution within the coating material composition itself, rather than applying different coatings to different regions. The coating material comprises ceramic particles with specific particle size distribution (fine particles 0.1-10 μm and coarse particles 10-50 μm) and colloidal silica in controlled amounts, which naturally creates the hardness gradient during drying without complex multi-step coating processes.
3Strength
If a dense surface layer is formed on the outer peripheral wall, then the wear resistance is improved, but the heat shock resistance deteriorates
Solution Approach 1:
The patent creates a hardness gradient within the coating material itself through particle size distribution and colloidal silica content control. The outer peripheral portion contains higher proportions of fine particles and colloidal silica for hardness and wear resistance, while the inside portion contains more coarse particles for lower hardness and heat shock resistance, eliminating the need for separate dense surface layers.
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 achieves high hardness and heat shock resistance, preventing damage from large vibrations and shocks while acting as a cushion to relax heat shock, making it suitable for heavy-duty applications like diesel engines and construction machines.
Implementation Method 1
the migration of colloidal silica or alumina toward outer periphery is suppressed
Implementation Method 2
water in the coated material comprising ceramic particles having an average particle size of 20-50 μm is easily absorbed by the honeycomb structure, resulting in densification in the inner side of the outer peripheral wall
Data Source
Figure 1(a)~2
AI summary
A ceramic honeycomb structure comprising a ceramic honeycomb body having cell walls defined by a large number of longitudinally extending cells, and an outer peripheral wall formed on an outer peripheral surface of the ceramic honeycomb body, the outer peripheral wall being formed by coating longitudinally extending grooves defined by cell walls on the outer peripheral surface of the ceramic honeycomb body with a coating material, and the outer peripheral wall having higher hardness in its outer peripheral portion than in its inside portion in a thickness direction.