Femtosecond laser spiral scanning ablation of SiCf/SiC composites

To investigate the single-layer removal process and mechanism during the machining of SiCf/SiC composites, this study utilized femtosecond pulse lasers for spiral scanning single-layer ablation experiments. The study examined the effect of power and scanning speed on the average processing depth, edge protrusion height, and central protrusion height of the boreholes. The results revealed that as average power increased and scanning speed decreased, the hole depth and edge protrusion height increased, with excessively low scanning speeds leading to larger central protrusions. The optimal parameters for spiral scanning single-layer ablation were obtained, with a power of 4 W and a scanning speed of 35.78 mm/s. Furthermore, the change of microstructural within and around the blind holes was analyzed at different energy densities. At an energy density of 55.63 J/cm2, the deposits inside the borehole transited from nanoscale particles and debris to larger clusters, causing the gradual disappearance of periodic structure on the fibers and matrix. The deposits at the hole's edge evolved from dispersed particles to aggregated larger particles. At an energy density of 148.35 J/cm2, the formation of flocculent substances and thicker deposits occurred, which could be readily removed through ultrasonic cleaning. Finally, the ablation results were analyzed by XRD, DXR, XPS, and EDS in terms of stress, elemental and chemical bonding changes. This research provides a theoretical foundation and technical support for the high-quality and efficient hole making of ceramic-based composites.