Splashing effects and mechanism in water jet-guided laser processing of Cf/SiC composites

Water jet-guided laser (WJGL) processing of ceramic matrix composites offers smooth cutting surfaces and minimizes defects such as delamination, burrs, and recast layers. However, the processing ability of WJGL is limited by the stability of the water jet. Splashing is a critical factor that affects water jet stability. This study investigates the splashing morphology and its impact mechanism during WJGL processing of continuous carbon fiber reinforced silicon carbide (C_f/SiC) composites. High-speed cameras were used to capture splashing morphologies and laser transmission states during drilling and grooving. The results indicate that the splashing morphology was significantly affected by the water jet speed and the micro-hole/groove depth, resulting in behaviors such as water accumulation, droplets falling, rebound droplets, splash impact, water film, and mist, which distorted or even broke the water jet. The laser escaped in the distorted water jet, leading to a reduction in material removal rate. The splashing at the water jet speed of 160 m/s resulted in a 61.1 % reduction in material removal rate during drilling compared to 40 m/s. In addition, a method of placing a porous water-absorbing material on the workpiece surface was proposed, which effectively improved the material removal rate. This paper presents a theoretical basis for comprehending and addressing splashing in WJGL processing.