Zsolt Szalay

Wood Surface Modification in Diffuse Coplanar Surface Barrier Discharge for Creating Water Repellent Films from N2/HMDSO and N2/HMDS Mixtures.

Diffuse Coplanar Surface Barrier Discharge was successfully tested for creating a water-repellent surface from HMDSO and HMDS compounds on samples of spruce wood (Picea abies, Karst). The best results were achieved when the treated sample was in continuous motion during the course of film deposition. Best hydrophobic coating was achieved for 29% of total gas flow through the HMDSO and HMDS liquid. The surface free energy of modified surface was 30 mJ/m2 for HMDSO and 24 mJ/m2 for HMDS mixtures. The 50 μl water droplet required (180±30) min to penetrate into the modified spruce in HMDSO mixture and (213±30) min in HMDS mixture. This is more than 20 fold increase compared to the unmodified spruce. The chemical composition of deposited layer was analyzed by ATR-FTIR. The presence of Si-O-Si and Si(CH3) functional groups was confirmed.

Coplanar Dielectric Barrier Discharge on a High-Permittivity Dielectric Surface

Coplanar barrier discharge with concentric electrode configuration was used to study the processes affecting the mutual interactions of individual discharge microfilaments. To elucidate the role of surface charge on the dielectrics, discharge characteristics on various coatings with different permittivity have been investigated. Owing to the thermo-chemical erosion of the coating with particularly high-permittivity (εr = 12000) a novel regime of discharge appearance is observed, consisting of micro-plasma spots filling the pores in high-ε dielectric created by the action of initial microfilaments and bright, extended length plasma channels arching over the interelectrode space. A visual record of this phenomenon is presented.