The ion beams generated from gases, methane-hydrogen, oxygen, and nitr
ogen in a low voltage ion source with kinetic energy 400-1,000 eV, wer
e used to modify the surfaces of commercial carbon fibers. After the i
on treatments, single filament tensile stress as well as fiber-epoxy i
nterfacial adhesive strength was found to increase substantially. The
modification by ion beams results in profound alterations of surface m
orphology and topology. The enhanced mechanical properties of carbon f
ibers are discussed from fiber surface microstructures acid ion beam p
rocessing parameters.