SURFACE FREE-ENERGY OF CARBON-FIBERS WITH CIRCULAR AND NONCIRCULAR CROSS-SECTIONS COATED WITH SILICON-CARBIDE

Mesophase pitch-based carbon fibers with circular and non-circular (ribbon, C-shaped) cross sections were coated with a thin, approximately 100-150 nm SiC-layer, using a CVD technique. The sur face free energy of the uncoated and SiC-coated carbon fibers was determined by measuring the contact angle of a variety of liquids with known polar and dispersive components of their total surface free energy. It was shown that the polar and dispersive components of the total surface free energy of the carbon fibers depends strongly on both the SiC-layer as well as on the shape of the cross section.