| AVS 55th International Symposium & Exhibition | |
| Advanced Surface Engineering | Thursday Sessions |
| Session SE-ThP |
| Session: | Advanced Surface Engineering Poster Session |
| Presenter: | N. Apetroaei, Nagoya University, Japan |
| Authors: | N. Apetroaei, Nagoya University, Japan N. Saito, Nagoya University, Japan O. Takai, Nagoya University, Japan |
| Correspondent: | Click to Email |
The aim of this paper is to contribute to a better understanding of the mechanisms, which conducted to the electrode surface modifications using the water plasma, and to correlate these experimental results with the results which we obtained from diagnosis of the plasma. The water pulsed plasma is non-equilibrium highly collisional plasma produced at rather high pressure by high voltage pulse applied to a special system of electrodes. Different electrode materials, shapes and configuration have pronounced effect on liquid discharge. In our case were used to form the electrodes, wire and rod of copper, tungsten, tantalum, molybdenum, nickel and stainless steel (SUS) with different diameter from 1mm up to 3mm for tip to tip electrode configuration and sheet of Cu and SUS for plan to plan and tip to plan electrode configuration. The high voltage power supply (4 kV) generates bipolar pulses in the range of 2 – 10μs and frequency in the range of 1 - 30 kHz. Modification of surface properties of a metallic electrode has been analyzed by contact angle measurement, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Water plasma changes the electrode surface structure. There are few things which conduct to these changes. One is strong local heating and formation of hot spots at the electrode surface. Temperatures above the boiling point of the electrode material can de necessary depending on the work function of the metal. Another is discharge physical sputtering caused by the collision of energetic electrons or other heavy particles with electrode surface. Another is the chemical reaction between water plasma and electrode surface. Water plasma generates very active species such as: chemical aggressive atoms and radicals, charged particles-electron and ions, excited atoms and molecules. After solution plasma we observed that the proprieties (surface tension, adhesion work, roughness, oxidization) of electrode surface have changed, comparing to a new one unused to water plasma. Surface wettability is improved from contact angle measurements and SEM images show an increase of surface roughness.