Surface modification and submicron structure of carbon fibers through high current pulse

This paper investigated the behavior of carbon fibers subjected to a ∼20 kA, ∼5 μs high current pulse. It was found that the broken fibers and submicron particles were generated by electrical explosion process. After high current pulsed discharge, the fiber diameter increased significantly, from 5-7 μm to ∼13 μm. Also, the surface rupture of carbon fibers with valleys of hundreds of nanometers was observed. Most notably, the submicron particles appeared with two typical shapes (near-sphere and square). The high current pulsed discharge of carbon fibers can be divided into three stages, namely, heating stage, phase change stage, and explosion stage. Indeed, the electrical explosion process occurred in the last stage of ∼200 ns. The nature behind these results is closely related to the plasma development during the explosion process. The plasma expansion due to a large plasma thermal stress leads to the incomplete explosion. In the explosion stage, the current passing through the fibers exhibited a huge fluctuation, indicating plasma instabilities. Finally, the physical mechanisms, how to affect the surface morphology of carbon fibers, are presented.