Effect of energy density and feeding speed on micro-hole drilling in C/SiC composites by picosecond laser

The effect of energy density and feeding speed on micro-holes was investigated, which were machined in C/SiC composites by picosecond laser. Morphologies and elemental compositions of the machined holes in 2 mm and 3 mm thickness specimens were analyzed. The results indicated that both energy density and feeding speed had remarkable effect on the quality of micro-holes, especially on the exit side and cross-section of micro-holes. While the circularity of drilling holes on the entry side was affected by the energy density and feeding speed slightly. Additionally, the machining debris also played an important role in the quality of micro-holes. The micro-holes were consisted with three elements C, Si, and O, and those predominantly attributed to CC (sp²), CC (sp³) and SiO bonds. Moreover, the laser machining process was discussed, which was responsible for the formation of the debris.