Summary

Laser treatment of a carbon/carbon reinforced composite was studied. The composite was produced initially using plane weave carbon fiber and phenolic resin. The carbonization of the phenolic resin was carried out at 1000 degreesC in an argon environment for several hours. A Nd:YAG pulsed laser with 10 Hz repetition rate was used to irradiate the workpiece. The laser output power intensity could be changed between two levels: low and high power intensity. SEM and EDS were carried out to examine the surface of the composite and quantify the elemental composition in the region irradiated by the laser beam. It was found that at low power intensities, high temperature oxidation reactions result in the decomposition of carbon fibers and globules-like particles form on the surface. In the case of high power intensities, surface ablation and no resolidification of carbon is observed after the ablation process. This, in turn, results in a deep cavity with almost no taper