AVS 53rd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA1
Use of Hydrogen or Oxygen Atmospheric Pressure Plasmas for the Surface Treatment of Metals

Wednesday, November 15, 2006, 2:00 pm, Room 2011

Session: Atmospheric and Microplasmas
Presenter: F. Reniers, Unviersité Libre de Bruxelles, Belgium
Authors: E. Michel, Unviersité Libre de Bruxelles, Belgium
E. Silberberg, ARL, Arcelor Group
F. Reniers, Unviersité Libre de Bruxelles, Belgium
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Oxygen or hydrogen-based dielectric barrier discharges were used to remove organic contaminants from steel surfaces or to reduce surface oxides on various metals (copper, iron). Contaminated steel surfaces were treated using atmospheric pressure oxygen based plasmas in a DBD. In our configuration, the hot electrode only is covered with the dielectric, whereas the other electrode being the sample. Voltages between 1 to 4 kV were applied between the electrodes, at a frequency varying between 5 and 30 kHz. The plasma gas consisted in a mixture of He-O@sub2@, at atmospheric pressure, or pure oxygen at a reduced pressure. The plasma chemistry was characterized using optical emission spectrometry (OES). The electrical characteristic of the plasma were recorded as a function of the applied voltage, frequency and gas composition. The kinetics of decontamination was studied by Auger electron spectroscopy (AES) and infrared spectroscopy (IRRAS- FTIR). The effect of the frequency, the applied voltage, the discharge current, the initial amount of contamination and the gas composition on the kinetics of decontamination was studied. The resulting surface state of steel was investigated using AES and X-ray photoelectron spectroscopy. A macroscopic model for the kinetics of decontamination is proposed. Oxidised steel and copper surfaces were then exposed to low pressure hydrogen plasmas and high pressure hydrogen-helium plasmas. Although the DBD configuration was similar to the one developed for oxygen plasmas, the plasma reactor was attached to a XPS-UHV chamber to avoid post oxidation during transfer in air. Complete reduction of iron oxide and copper oxide could be achieved. The relationships between the plasma parameter (pressure, charge density, and frequency), the OES intensity of the hydrogen line, and the efficiency of surface oxide reduction were established for iron oxide.