Research on hole depth in femtosecond laser deep micropore processing technology based on filament effect

Ceramic-based composites have been applied to turbine components of new-generation aerospace engines due to their excellent properties. Despite the superior high-temperature resistance of SiC/ SiC composites, it is necessary to combine with film cooling technology to guarantee normal function of turbine components. However, SiC/SiC composites are typical difficult-to-process materials,and the depth of film cooling holes have increasingly high requirements, which have become one of the major problems in the manufacturing of aerospace engine turbine parts. In this paper, the spatial energy density distribution based on filament effect of femtosecond laser was theoretically studied, it is revealed that the filament effect of femtosecond laser with high single pulse energy will lead to the peak of energy density shift towards the negative defocus direction. Based on the theoretical research, the experimental study on the processing of deep micropore in SiC/SiC composites by femtosecond laser was carried out, main results show that in equal conditions, the depth of micropore in feed trepanning is deeper than that in trepanning, and that in trepanning is deeper than that in direct punching. This research provides both theoretical and technical support for processing of micropore with high aspect ratio by ultrafast laser on the difficult-to-process materials, which have high practical value in the aerospace field.