THE EFFECT OF CF4 PLASMA TREATMENT ON THE WETTABILITY OF CARBON FIBER-REINFORCED PLASTIC SURFACE

10.25712/ASTU.1811-1416.2025.04.001

Abstract

The article investigates the effect of inductively coupled CF₄ plasma on the wettability of carbon fiber-reinforced plastic surfaces. Plasma treatment was performed using a plasma power of 200 W and a CF₄ gas flow rate of 100 cm³/min. The treatment duration ranged from 5 to 40 minutes. The surface elemental composition was analyzed using X-ray energy-dispersive spectroscopy. The surface morphology was examined using electron microscopy and atomic force microscopy. Raman spectra, photoluminescence intensity, and contact wetting angles were also studied.  After 20 minutes of treatment, the fluorine content on the surface reached 27 at.%, with only a slight increase observed when the treatment time was extended to 40 minutes. A change in the state of the carbon fiber surface from hydrophilic to hydrophobic was detected as a result of plasma exposure. Contact angle measurements following plasma treatment showed an increase of 60–65° compared to the initial values. A direct relationship between the duration of plasma exposure and the wetting angle is shown. The maximum contact angle of 135° was achieved after 40 minutes of treatment. The observed effect is attributed to a reduction in surface energy due to the formation of C–F bonds during plasma fluorination. An additional contribution to the enhanced hydrophobicity is provided by changes in surface morphology caused by plasma etching. In this case, the hydrophobic behavior of the surface can be theoretically described by the Cassie–Baxter model and/or its modification proposed by Marmur.