Accumulative effect in femtosecond laser ablation of SiCf/SiC ceramic matrix composites

Silicon carbide fiber reinforced silicon carbide ceramic matrix composites (CMC-SiC_f/SiC) have been widely used in aerospace and other fields due to their excellent properties such as high hardness, oxidation resistance and high temperature resistance. Different from the traditional machining methods, laser processing technology has great application prospects in CMC-SiC_f/SiC. In this paper, the single-pulse ablation test and multi-pulse cumulative ablation test of CMC-SiC_f/SiC were carried out by femtosecond laser at different powers with a wavelength of 1035 nm. A series of experiments were designed to process the ablation pits on the material surface. The diameter of the ablation pits was observed by laser confocal microscope. The variations of the ablation threshold of CMC-SiC_f/SiC surface under different pulse energies and pulse numbers were studied. The results show that the multi-pulse ablation threshold of CMC-SiC_f/SiC decreases with the increase of pulse number, and there is a significant cumulative effect. The multi-pulse ablation threshold of CMC-SiC_f/SiC is mainly related to the number of pulses, which is determined by two parameters: accumulation factor and single-pulse ablation threshold. The single-pulse ablation threshold of CMC-SiC_f/SiC is 1.1914 J/cm², and the accumulation factor is 0.6245. In femtosecond laser processing, the pulse accumulation effect has a significant influence on the ablation of hard and brittle material CMC-SiC_f/SiC. This study can provide technical guidance for process optimization.