Atmospheric Pressure Plasma Treatment of Thick Insulating Workpieces
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Solution Overview
Problem
Existing methods for atmospheric pressure plasma treatment are limited in treating materials thicker than 6 mm due to non-uniform discharge channel formation and subsequent surface activation, restricting the effective range of treatment.
Innovation Solution
The method employs at least two barrier electrodes with capacitive coupling, where high voltage is applied to the electrode surfaces facing the workpiece, enabling a uniform plasma discharge over the entire workpiece surface through plasma species expelled from the gap, allowing for precise and energy-efficient treatment regardless of workpiece dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrode gap is increased to treat thicker materials, then the treatment thickness range is improved, but the discharge channel formation becomes non-uniform resulting in non-uniform surface activation
Solution Approach 1:
The electrode is divided into multiple segments (first electrode segment and second electrode segment) arranged one behind the other in the direction of movement. Each segment creates a discharge channel that contributes to uniform surface activation across the entire workpiece surface, allowing treatment of thicker materials while maintaining uniformity.
Solution Approach 2:
The discharge channels are extended in the direction of movement (third dimension) by arranging electrode segments sequentially. This dimensional extension allows the plasma discharge to uniformly activate the entire workpiece surface area without requiring an increased electrode gap, thus enabling treatment of thicker materials while maintaining activation uniformity.
2Reliability
If barrier electrodes are used to create discharge channels, then plasma discharge is ignited, but the plasma acts on the surface only along a narrow strip corresponding to the gap width
Solution Approach 1:
Multiple discharge channels from different electrode segments are merged to cover the entire workpiece surface. The plasma discharges from each segment combine to activate the full surface area, transforming the narrow strip limitation into comprehensive surface treatment capability.
Solution Approach 2:
The treatment area is expanded by extending the discharge channels in the direction of movement through multiple electrode segments. This dimensional extension transforms the narrow strip discharge into a broad area treatment system covering the entire workpiece surface.
3Manufacturing precision
If high voltage is applied to ignite plasma discharge, then surface activation is achieved, but energy consumption increases
Solution Approach 1:
The plasma discharge is maintained continuously as the workpiece moves through the electrode segments. The continuous plasma action ensures consistent surface activation quality while optimizing energy utilization through sustained discharge rather than intermittent high-voltage pulses.
Solution Approach 2:
The voltage parameters are optimized across multiple electrode segments to achieve efficient plasma ignition and maintenance. By distributing the voltage application across segments rather than requiring extremely high voltage from a single electrode, energy consumption is reduced while maintaining activation quality.
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 ensures uniform surface activation across larger areas, improving adhesion properties and energy efficiency by adapting the discharge to the workpiece dimensions, while also allowing for double-sided treatment and precise control over plasma ignition.
Implementation Method 1
A high voltage in the form of an alternating voltage is applied to the barrier electrodes in order to ignite a plasma discharge in the gap
Implementation Method 2
capacitive coupling occurs when the workpiece approaches the electrode at an adapted distance and with a suitable selection of the other parameters (high voltage, atmosphere) through the dielectric mass of the workpiece
Implementation Method 3
Depending on the type of gas, the surface of the workpiece is oxidized by the discharge, or other chemical groups such as amines, amides or imides are incorporated. This increases the surface energy of the workpiece and thus enables or improves adhesion to paints, varnishes, adhesives or other coatings.
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
The invention relates to a method for treating plasma under continuous atmospheric pressure of, in particular, electrically insulating workpieces, in particular material plates or strips. According to said method, the workpiece which is to be machined, is arranged at a distance below at least one electrode which is made of two barrier electrodes, which are arranged in a successive manner in the direction of displacement with a gap, and which extends in a manner which is transversal to the direction of displacement at least over the width of the surface of the workpiece which is to be machined. The electrode and the workpiece are mutually offset in the direction of displacement. High voltage, which is in the form of an alternating voltage, is applied to the barrier electrodes, in order to provoke at least plasma discharge in the gap. The plasma discharge is driven by the gas flow from the gap in the direction of the surface of the workpiece which is to be machined. The invention is characterised in that the surfaces of the barrier electrodes which are oriented towards the surface of the workpiece which is to be machined are impinged upon with high pressure.