EFFECTS OF PLASMA COMPOSITION ELEMENTS ON THE SURFACE MODIFICATION OF CARBON MATERIALS BY NITROGEN PLASMA

抄録

This investigation was conducted on the surface modification of Glassy carbon(GC) material by R.F. glow discharge plasmas with the aim of investigating the surface nitriding for the GC materials with the nitrogen plasma. The contact angles for water to GC surface after the plasma treatment was measured. And their surfaces were analyzed by using Raman spectroscopy and ESCA. Nitrogen-plasma treatment makes the GC surface hydrophilic. The difference Δθ of the contact angles between those before the treatment (80°) and those at 30minutes after the treatment was investigated. Δθ is considered the effects of plasma treatment. As input power increased from 10W to 70W, the difference Δθ increased (on power electrode : from 46° to 63°, on earth electrode: from 32° to 58°). The composition ratios, O/C and N/C on the untreated GC surfaces were 0.0 and 0.0, respectively. Upon treatment with N₂ plasma, this ratio increased to 0.12(O/C) and 0.18(N/C) for the GC surface. Nitrogen atoms and oxygen atoms, namely, were introduced to the GC surface. Introduction of nitrogen atoms was caused by the nitrogen radicals and nitrogen ions. The oxygen atoms were introduced by nitrogen ions. Nitrogen ions were accelerated by the sheath voltage and bombarded the GC surface at high energy. As the result, the active and long life-time radicals were generated. The reaction between these radicals and the oxygen in the air took place when they were taken out from the treatment chamber to the air after plasma treatment.
The contact angle decreased by introducing the functional groups having nitrogen atoms and oxygen atoms onto the GC surface with nitrogen plasma. The surface nitriding of the carbon materials can be made easily with the short-time treatment of nitrogen plasma.