Laser processing of small holes with large aspect ratio in SiC_f/SiC composites

SiC fiber reinforced SiC ceramic matrix composites (SiC_f/SiC composites) are characterized by anisotropy, high hardness, and low electrical conductivity, which makes it difficult to process small holes with a large aspect ratio. Femtosecond laser processing and water-guided laser processing are advanced laser processing methods that offer the advantages of controllable processing quality, automated processing, and low processing cost, making them preferred technological solutions for addressing the challenge of small holes with large aspect ratios in SiC_f/SiC composites. The femtosecond laser rotary drilling (FLRD) and the water jet guided laser drilling (WJGLD) are adopted to produce small holes with an aspect ratio of 10 in 3 mm thick SiC_f/SiC composites. The morphology and physical phases of the entrance, exit, and wall of the small holes were analyzed, and the hole diameter, wall roughness, and processing efficiency of the small holes were compared. The results show that the exit quality of the laser-processed holes is better than the entrance quality, and the FLRD has the advantages of a sharp orifice, good roundness, and small taper, while the WJGLD laser has the advantages of smooth and clean orifices, clean hole walls, and high processing efficiency. To address the demand for small holes with large aspect ratios in heat-resistant components of SiC_f/SiC composites, suitable drilling technology should be selected by considering factors such as processing quality, processing efficiency, and processing conditions.