Coated Monolith Spray Deposition Corner Radius Control
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Solution Overview
Problem
In the field of catalysis, particularly for automotive exhaust treatment, existing methods for coating monolithic support members with catalytically active materials result in excessive material accumulation in fillet portions due to large concave radii at the corners of channels, leading to reduced catalytic activity and increased pressure loss.
Innovation Solution
A method involving a suspension with specific viscosity and solid content, dispersed into a gas stream and directed along the axial direction of channels, achieving a coating with minimized material deposition in corners, characterized by a small radius of curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional coating methods (e.g., dip coating) are used to apply catalytically active materials onto monolithic support member walls, then the coating process is simple and efficient, but large concave radii are formed in the fillet portions at channel corners, causing excessive coating material accumulation that reduces catalytic activity and increases pressure loss
Solution Approach 1:
The patent changes the physical parameters of the coating process by using a spray application method with controlled suspension properties (viscosity 0.5-100 mPas, solid content 1-40 wt.-%, particle size d90 ≤ 10 µm) instead of dip coating. This parameter change enables precise control of coating deposition, reducing the fillet radius to R ≤ 0.2 mm while maintaining manufacturing efficiency through automated spray systems.
Solution Approach 2:
The patent employs pneumatic spray technology to apply the coating suspension onto the monolithic support member. A gas stream carries the suspended coating material through spray nozzles that atomize and deposit the coating in a controlled manner, enabling precise fillet radius control and uniform coating thickness that cannot be achieved with conventional dip coating methods.
2Ease of operation
If the concave radius of fillet portions is large, then the coating application is easier and more uniform, but a high amount of catalytically active material is trapped in the fillet portions where it is not accessible to the exhaust gas stream, representing a waste of precious metals
Solution Approach 1:
The spray coating method using gas stream atomization enables precise control of material deposition. The suspended coating material is delivered as a fine aerosol that can be controlled to deposit only where needed, minimizing accumulation in fillet portions while ensuring complete coverage of active surfaces, thus reducing precious metal waste.
Solution Approach 2:
By controlling suspension parameters (particle size d90 ≤ 10 µm, viscosity 0.5-100 mPas, solid content 1-40 wt.-%) and spray parameters, the patent achieves optimal deposition patterns that prevent excessive material accumulation in fillet portions while maintaining ease of application through automated spray systems.
3Device complexity
If large concave radii are present in the fillet portions, then the coating structure is simpler to form, but the accessible surface area for exhaust gas flow is reduced, leading to loss of catalytic activity
Solution Approach 1:
The patent reduces the fillet radius parameter to R ≤ 0.2 mm through controlled spray deposition, which increases the accessible surface area for exhaust gas flow and maintains high catalytic activity. This parameter change is achieved while keeping the coating structure simple through uniform application of suspended materials with controlled rheological properties.
4Ease of manufacture
If large concave radii are formed in the fillet portions, then the coating process is more tolerant to variations, but the pressure loss through the monolithic support member increases undesirably
Solution Approach 1:
By controlling the fillet radius to R ≤ 0.2 mm through spray parameter optimization, the patent reduces flow resistance and pressure loss in the monolithic support member. The controlled suspension parameters (viscosity, solid content, particle size) ensure consistent deposition that maintains smooth flow paths while tolerating normal process variations.
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
This approach minimizes coating material in corners, enhancing catalytic activity and reducing pressure loss, while optimizing the use of precious metal components, thereby improving the efficiency and economic viability of catalytic articles.
Implementation Method 1
said suspension is suitably dispersed into a gas stream, and the resulting gas stream is subsequently directed towards the monolithic support member
Implementation Method 2
dispersing and directing is performed using a device containing at least one spray nozzle
Implementation Method 3
a coating is applied onto the walls of the monolithic support member
Data Source
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AI summary
The invention relates to a monolithic support member comprising channels with walls separating the channels from each other and having a coating deposited thereon, the non-coated channels having a polygonal cross-section profile, wherein the mean thickness dc of the coating in a corner of said cross-section profile is smaller than or equal to the mean thickness dE of the coating on an edge of said cross-section profile plus 85 micrometer; and further relates to a method for the preparation of such coated monolithic support member, the method comprising (i) providing a suspension having a viscosity in the range of from 0.5 to 100 mPas and having a solid content in the range of from 1 to 40 wt.-%, (ii) dispersing the suspension into a gas stream to obtain a gas stream comprising droplets having a droplet size in the range of from d10 greater than or equal to 1 micrometer to d90 smaller than or equal to 100 micrometer; and (iii) directing said gas stream comprising said droplet towards the monolithic support member along the axial direction of the channels of the support; and still further relates to the use of such coated monolithic support member, in particular as catalytic article in the automotive exhaust gas treatment.