Nanosecond laser ablation behavior of C/SiC composites under water layer protection: Experiments and theoretical investigation

•The nanosecond laser ablation behavior of the C/SiC composites in the air and water environments was investigated.•The mechanism of material removal in two processing environments was systematically analyzed and compared from the perspective of experiments and thermodynamic theory.•The energy balance equation of the laser processing material surface in two environments is established.•The existence of a water layer effectively avoids the redeposition of SiO2 on the processing surface and alleviates heat accumulation, and the processing quality is better.