Honeycomb Monolith Coating via Dynamic Piston Velocity Control
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Solution Overview
Problem
Existing methods for catalytically coating honeycomb monoliths often result in inhomogeneous coatings due to bubble formation in the coating slurry, leading to uneven deposition of the catalytic layer, especially when high viscosity slurries are used, which can cause defects and non-uniform coatings.
Innovation Solution
The method involves controlling the velocity of the piston's backstroke movement in the coating apparatus to prevent bubble formation by setting a threshold velocity based on the slurry's characteristics, using a Gaussian profile for the backstroke movement, and employing in-process-control with sensors to adjust the piston's velocity in real-time to minimize gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the piston velocity is increased to accelerate the coating process, then productivity is improved, but bubble formation occurs leading to inhomogeneous coating
Solution Approach 1:
The piston velocity is made dynamic rather than constant. The control unit adjusts the piston velocity during the coating process based on real-time feedback from sensors that detect coating progress and bubble formation, allowing the system to maintain high productivity while preventing defects when conditions require it.
Solution Approach 2:
A feedback control system is implemented where sensors monitor the coating process continuously and provide information to the control unit, which then adjusts the piston velocity accordingly. This closed-loop control ensures that productivity is maximized while coating uniformity is maintained by preventing bubble formation.
2Manufacturing precision
If high viscosity slurry is used to improve coating quality, then coating evenness is improved, but bubble formation is enhanced leading to defects
Solution Approach 1:
The system dynamically changes the velocity parameter of the piston based on slurry viscosity and coating conditions. By adjusting the piston velocity according to the specific slurry properties and real-time coating state, the system achieves even coating with high viscosity slurry while minimizing bubble formation through optimized flow conditions.
3Productivity
If fast coating speeds are applied to reduce processing time, then productivity is improved, but turbulent slurry flow occurs causing uneven slurry surface
Solution Approach 1:
The piston velocity is dynamically adjusted during the coating process. At the beginning of coating, lower velocities are used to maintain stable slurry flow and even surface. As coating progresses and productivity requirements increase, the velocity can be increased while the control system monitors for turbulence and adjusts accordingly to prevent surface instability.
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 significantly reduces the risk of gas bubbles in the coating medium, ensuring a uniform and even coating across all channels, thereby achieving a high-quality, uniformly coated substrate with minimal defects and improved exhaust gas purification performance.
Implementation Method 1
a cylinder (102) filled with liquid (103) and having a piston (101), wherein the liquid-filled cylinder (102) communicates with a tank (112), in the interior of which a displacement body (111) is arranged in such a way that, when the piston (101) is moved, the displacement body (111) is moved proportionally by the liquid (103)
Implementation Method 2
bring the openings on one side thereof into contact with the coating medium and to draw the liquid coating medium through the openings, e.g. channels, of the substrate by applying a vacuum to the opposite side of the substrate
Implementation Method 3
if fast coating speeds are applied and coating slurry tends to get turbulent while being pumped into the coating chamber within a short timeframe
Data Source
AI summary
A method of catalytically coating a honeycomb monolith, in particular a so-called flow-through monolith, is featured. The process involves quite precisely coating the monolith with a method that uses an indirect coating via a displacement body. The method included controlling the process by monitoring certain measures and controlling the liquid coating medium feed as to limit bubble formation in the liquid coating medium.