Removal mechanism of 2.5-dimensional carbon fiber reinforced ceramic matrix composites processed by nanosecond laser

C/SiC composite material is widely used in aerospace fields because of its excellent properties; however, it is difficult to be removed and processed. In this paper, the 2.5-dimensional C/SiC composite material was ablated by nanosecond laser to explore the laser removal mechanism. Firstly, the laser ablation experiment was carried out to investigate the gradual process of ablation morphology with the increasing laser power density. Secondly, the characteristics of ablation holes were analyzed, and the effects of laser processing parameters and fiber orientation on the ablation morphology and size were studied. In addition, the ablation morphology of needle-punched fiber area was analyzed to expound the unique ablation removal characteristics of 2.5-dimensional C/SiC composites. At last, ablation removal mechanism of 2.5-dimensional C/SiC composites was summarized, and the model of ablation removal process was established. The results indicated that ablation morphology was evolved from nothing to ablation mark, to fiber expansion, to fiber shrinkage and tension, to resolidification, to removal holes, and to increasing holes with laser power density. Besides, the ablation morphology in needle-punched fiber area was different from elliptic ablation morphology in the 0° or 90° fiber area, the ablation holes in the needle-punched fiber area were smaller and deeper, and the ablation holes were approximately circular. The results would provide theoretical basis and technical support for processing functionalized structure of 2.5-dimensional C/SiC composites by nanosecond laser, such as blind holes, grooves, and square holes.