The main focus of the Optimized Wire Treatment (OWIT) project is to develop and evaluate a new deposition method to achieve uniform coatings with excellent physical properties on fibers and wires. The major limitation of the standard sputtering technique, which uses point sources or planar targets, is the inability to introduce the majority of the sputtered species to the substrate.
Researchers have now proposed a magnetron sputter system (Figure 1) operating in High Power Impulse (HIPIMS) mode that stores metal ions in significant quantities. These ions can be found at the chamber walls, and can be continuously used for the deposition process.
This helps in maintaining a high level of self-sputtering at comparatively low power inputs. This technique provides new coatings with distinct physical, chemical and electrical properties including long chemical and mechanical lifetime, high ageing quality, and good mechanical strength.
Figure 1. The experimental setup with four essentially balanced planar magnetrons (2” Ti targets), Langmuir probe, and the system of capillaries used to introduce wires from atmospheric pressure
Objectives of New Deposition Technique
The following major objectives were taken into account to evaluate the new method and deposition technique:
- Using experimental data acquired through plasma diagnostic tools, plasma modeling can be performed with the particle-in-cell (PIC) and Monte Carlo methods. The optimum properties of the bulk plasma, including field distribution, density, geometry and so on can be determined through extensive plasma modeling and calculations.
- New technological advancements were achieved in the field of smart processing of wires. The main difficulty in this project involves concentrating high-density plasma in a small cylindrical volume with a comparatively large length.
The researchers aim at producing a suitable plasma shield around wires to simultaneously deposit and implant the constitutive coating species. The new plasma configuration facilitates high deposition rates and hence high treatment speeds. The future work will focus on obtaining perfect cylindrical plasma geometry to ensure homogeneous treatment throughout the wire surface.
- Using the Hiden Analytical ESPion Advanced Langmuir Probe, plasma diagnostics were performed. The probe was inserted into the middle of the discharge volume between four essentially balanced magnetrons to analyze various power modes at the active phase of HIPIMS plasma generation.
A counting device was used to convert the triggering waveform into a single pulse under the conditions where the cycle consists of over one pulse. Triggering was induced 5µs prior to the first edge level of the discharge voltage at the start of each cycle. Under this circumstance, the probe can deliver 125ns resolution to determine key plasma parameters including plasma and floating potentials, electron temperature and ion and electron densities.
This information has been sourced, reviewed and adapted from materials provided by Hiden Analytical.
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