Femtosecond Laser Two-Step Rotary Drilling Method for SiCf/SiC Composites

Abstract A femtosecond laser method for high-quality and high-efficiency micro-hole fabrication of SiCf/SiC composites is proposed for this difficult-to-machine material. The influence of optical wedge parameters in the femtosecond laser rotary optical system on the size of the generated annular beam spot and the beam deflection angle was investigated. And the processing parameters of femtosecond laser drilling were obtained by single-layer ablation considering efficiency and quality. By implementing two-step rotary drilling, micro-holes with an entrance diameter of 501.4 μm, an exit diameter of 499.6 μm, a taper of 0.02 deg, and good quality at both ends were achieved. The evolution process and mechanism of hole formation in two-step rotary drilling have been demonstrated. Material removal and the phase changes of elements were studied, and no significant processing damage was observed in the cross-sections of SiC fibers and SiC matrix. By employing the two-step rotary drilling method, micro-holes with an aspect ratio of 6 were fabricated within a processing time of 145 s. This work provides technical support for high-quality and high-efficiency processing of SiCf/SiC composites using femtosecond laser technology.