Influence of surface morphology on processing of C/SiC composites via femtosecond laser

Carbon fiber reinforced silicon carbide (C/SiC) was processed with an 800 nm femtosecond laser, and the results were analyzed through theoretical calculations and wave optics simulations. In the ablation experiment, C/SiC morphologies for different parameters such as laser power, defocus distance, and scanning speed were compared. It was found that the roughness prior to processing of the C/SiC surface noticeably affects the ablation effect. Beam waist radius, curvature radius, and electric field intensity of the femtosecond laser were calculated theoretically and the wave optics module was simulated in finite element software. Causes for the different morphologies can be explained directly through the simulation results from the perspective of the electromagnetic field. It was found that the microgroove quality of C/SiC processed subject to the femtosecond laser with high fluence is relatively higher and that the edge oxidation of the processing area can be effectively controlled through argon protection. The comparison between the simulation and the experiment results deepens the understanding of the ablation mechanism, which can provide references for the improvement in processing quality of ceramic matrix composites (CMC) by laser treatment.