Hollow Cathode Plasma Coating for Complex Internal Surfaces
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Solution Overview
Problem
Existing plasma deposition systems are limited in coating internal surfaces, particularly for components with complex shapes or varying sizes, and suffer from anode degradation due to coating exposure.
Innovation Solution
A system with adjustable coupling heads and an articulated arm arrangement allows for flexible attachment to workpieces of different sizes and shapes, incorporating a biasing system, vacuum source, and gas supply, along with removable shields and plasma reflectors to ensure even plasma application and minimize anode exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-size vacuum chamber is used for plasma deposition, then the system structure is simple, but it cannot accommodate workpieces of different sizes or complex shapes
Solution Approach 1:
The patent employs an articulated arm with multiple joints that can be dynamically repositioned to accommodate workpieces of various sizes and shapes. The coupling heads at the end of the articulated arm can be moved to different positions and orientations, transforming the static chamber into a dynamic system that adapts to different workpiece configurations.
Solution Approach 2:
The system is divided into modular components including the articulated arm, coupling heads, biasing system, vacuum source, and gas supply. This segmentation allows each component to be independently adjusted and configured for different workpiece requirements, enhancing overall system versatility without requiring complete system redesign.
2Reliability
If anodes are exposed to treatment gas and plasma, then plasma generation is effective, but the anodes deteriorate with time
Solution Approach 1:
The anodes are extracted from the direct plasma treatment zone by positioning them outside the workpiece interior. The biasing system applies voltage to the workpiece itself rather than to exposed anodes, removing the anodes from the harsh plasma environment while maintaining effective plasma generation within the workpiece.
Solution Approach 2:
The workpiece itself acts as an intermediary, serving as the cathode in the plasma discharge. This eliminates the need for separate anodes exposed to treatment conditions, as the workpiece directly participates in plasma generation through the applied bias voltage.
3Adaptability or versatility
If sealed volumes are created for treating long components, then field treatment is enabled, but the system cannot accommodate complex shapes or varying aperture sizes
Solution Approach 1:
The articulated arm provides dynamic positioning capability that eliminates the need for fixed sealed chambers. The coupling heads can be moved to accommodate different workpiece lengths, shapes, and aperture sizes without requiring complex sealing mechanisms or multiple fixed chambers.
Solution Approach 2:
The articulated arm system serves multiple functions: positioning coupling heads, accommodating various workpiece sizes, and providing flexible access to different geometries. This universal platform replaces the need for specialized sealed volumes for each workpiece type.
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
Enables efficient and uniform treatment of internal surfaces of components with complex shapes and varying sizes, reducing anode degradation and improving coating consistency.
Implementation Method 1
a vacuum source, for evacuating an interior of a workpiece
Implementation Method 2
a biasing system, for connection to a workpiece and anode such as to negatively bias a workpiece relative to an anode
Implementation Method 3
a glow discharge plasma is established from the gas stream or its components
Implementation Method 4
a gas supply, for introducing a gas containing a treatment material to said workpiece
Implementation Method 5
maintaining the interior of the workpiece at a reduced pressure. The treatment gas contains the element to be deposited or implanted and the pressure is low enough to establish and maintain the 'hollow cathode effect' in which the electron mean free path is slightly less than the diameter of the workpiece, thus causing electron oscillation and implantation or deposition of the desired element below or onto the surface of the component itself
Data Source
AI summary
A system (10) for coating surfaces of a workpiece (12) comprises a biasing system (242) for connection to said workpiece (12) and an anode (76) such as to negatively bias the workpiece relative to the anode and a vacuum source (42, 44) for evacuating an interior of the workpiece (12). A gas supply (224, 226, 228) is employed for introducing a gas containing a treatment material to said workpiece and a control system (244) controls the biasing system (242), the vacuum source (42, 44) and the gas supply (224, 226, 228) so as to establish a hollow cathode effect within the workpiece (12). A pair of coupling heads (16, 18) are supported on articulated arms (22, 24, 26) movable in one or more of three axes and include removable shields (78) to protect the heads (16, 18) and an anode mount (74) for receiving an anode (76). The articulated arms allow the system to accommodate a plurality of different shaped and different sized workpieces while the shields protect the coupling heads during a deposition process.