Study on Picosecond Laser Ablation Behavior and Mechanism of 2.5D C _f /SiC Composites Based on Multichannel Scanning

ABSTRACT

Carbon fiber‐reinforced silicon carbide (C _f /SiC) composites have attracted considerable attention for aerospace engine applications because of their outstanding high‐temperature stability and mechanical performance. Nevertheless, the pronounced anisotropy, elevated hardness, and brittle nature of these composites pose considerable difficulties for achieving high‐quality machining. This work focuses on elucidating the ablation characteristics and associated mechanisms under picosecond laser multichannel irradiation through numerical simulations and experiments. A temperature field simulation model was established to analyze the thermal evolution. The effects of laser parameters on groove morphology and ablation characteristics were further evaluated. The results indicate that thermal accumulation in the convex planar region decreased with increasing scanning interval and scanning speed. Increasing the laser power from 9 to 15 W led to a significant enlargement of the ablation groove, with the average width and depth increasing by 42.87% and 62.41%, respectively. Conversely, raising the scanning speed from 200 to 1000 mm/s led to substantial reductions of 47.99% in groove width and 59.90% in groove depth. SEM observations revealed recast layers, microcracks, and oxidation products in the ablated region. EDS and XPS analyses confirmed that the dominant ablation product was SiO ₂ generated by high‐temperature oxidation reactions. Microhardness measurements indicated that the hardness of the laser‐ablated region decreased by approximately 46.96% compared with the original region. In addition, laser‐assisted milling improves surface quality, reducing surface roughness by 21.90% compared with conventional milling.