The uniform treatment of carbon fiber surface in three-directional orthogonal fabric by oxygen-plasma

An oxygen-plasma treatment of carbon fibre surface in three-directional orthogonal fabric preforms was investigated in this paper. The effects of this treatment on the surface wettability and chemical components of the fibres in both the interior and surface regions of the fabrics were analyzed by using dynamic capillary method and X-ray photoelectron spectroscopy (XPS), respectively. A microdebonding method was employed to determine the uniformity of interfacial shear strength between the fibre and matrix in different regions of the carbon fabric-phenolic composites, and the flexural strength was also tested to evaluate the effects of the treatment. The results indicated that, the oxygen-plasma significantly improved the interfacial adhesion by etching, activating the surface of the fibres, and generating the oxygenic functional groups. However, for the fibres in different regions of the fabric, the degrees of the treatment were different, and a longer treatment time was needed to get the relative uniform effect through the fabric. Meanwhile, the loss of tensile property of the fibre due to treatment was investigated and found to be small in the range of useful treatments.