Multilayer Ceramic Substrate Micro-Channel Fabrication
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Solution Overview
Problem
Existing methods for manufacturing ceramic substrates for catalytic converters and filters, such as those used in vehicle exhaust systems, are limited by the geometrical surface area and flow characteristics, which can lead to inefficiencies in pollutant reduction and gas flow.
Innovation Solution
A method involving the formation of multilayer structures using specific polymer compositions and solvents, followed by precipitation to create green bodies with micro-channels that enhance surface area and allow for fusing of multiple green bodies into a substrate, improving both geometric surface area and flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional ceramic substrates with numerous channels are used, then geometric surface area is increased, but back pressure increases which is detrimental to engine performance
Solution Approach 1:
The substrate is divided into multiple layers (first layer, second layer, third layer) with different functions. The first layer provides mechanical strength, the second layer contains the micro-channel structure for catalytic activity, and the third layer protects the micro-channels. This segmentation allows optimization of each layer independently to achieve high surface area while controlling back pressure.
Solution Approach 2:
Different regions of the substrate have different properties. The micro-channels are strategically positioned and sized to provide high surface area in specific zones while maintaining open flow paths in other regions. The washcoat is applied selectively to enhance catalytic activity where needed without blocking flow paths.
2Area of stationary object
If micro-channels are extended all the way through the substrate, then surface area is maximized, but the surface layer must be removed requiring additional processing steps
Solution Approach 1:
The micro-channel structure is pre-formed within the green body during the extrusion process, before sintering. The extrusion die is designed with specific geometries that create the desired micro-channel patterns and wall thicknesses directly during manufacturing, eliminating the need for subsequent surface layer removal or complex post-processing steps.
3Strength
If multiple green bodies are fused together, then substrate strength is improved, but fusing difficulty increases
Solution Approach 1:
The fusing process utilizes controlled parameter changes including temperature, pressure, and atmosphere. Green bodies are fused at elevated temperatures (typically 500-1500°C) under controlled atmospheric conditions to promote sintering and bonding between particles. Pressure may be applied to enhance contact and bonding. These parameter changes facilitate strong bonding while maintaining manufacturing feasibility.
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 method results in substrates with increased geometric surface area and improved gas flow, enabling more effective pollutant reduction and efficient operation of internal combustion engine exhaust systems.
Implementation Method 1
contacting the third layer with a fourth solvent in which the third polymer is insoluble to precipitate said polymer, thereby forming a green body
Data Source
AI summary
A method of manufacturing a green body, the method comprising:providing:a third composition comprising a second substrate material, a third polymer, a fusing agent, and a third solvent;forming the third composition into a structure wherein the third composition forms a third layer; andcontacting the third layer with a fourth solvent in which the third polymer is insoluble to precipitate said polymer, thereby forming a green body.A substrate is further manufactured by:arranging a plurality of green bodies to form an assembly of green bodies;fusing the green bodies in the assembly together, thereby forming a precursor substrate; andsintering the precursor substrate, thereby forming a substrate.