Experimental and mechanism study on surface texture of CMC-SiC/SiC Prepared by Gas-Vibration assisted femtosecond laser processing

Silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (CMC–SiC/SiC), which are key materials for next-generation aero-engine hot-section components, face machining challenges due to the limited quality controllability achieved when using conventional methods. This study proposes and validates a novel gas vibration-assisted femtosecond laser (PHAROS Yb:YAG, 1032 nm) processing (GVA-FSLP) method, which enables the fabrication of high-quality surface textures on CMC–SiC/SiC. First, the influence of key parameters—pulse energy, repetition rate, scan number, and scanning speed—on the surface micromorphology and performance was systematically examined through baseline configuration and single-factor experiments. The results show that the pulse energy significantly affects the microgroove depth, low repetition rates promote the formation of distinct lamellar connections within the grooves, greater scan numbers lead to larger spatter deposition, and high scanning speeds cause sharp depth reductions. Subsequently, the response surface methodology was adopted to establish predictive models for the machining depth and surface roughness (R² > 0.99), enabling process optimization and controllable fabrication. Three bio-inspired surface textures were designed and fabricated: a turtle shell-inspired honeycomb, a biaxially symmetric branched fishbone, and shark skin-inspired structures. These textures achieved a 32-μm depth, 0.8-μm surface roughness, and 3-at.% oxygen content, demonstrating the superiority of GVA-FSLP for engineering high-performance textures. Finally, the microscopic mechanism of material removal during surface texture engineering was elucidated through tolerance analyses and microstructure evolution studies. GVA-FSLP is an effective machining approach that can reveal the underlying mechanisms for creating CMC–SiC/SiC textures without interfacial crack initiation/propagation, offering guidance for hot-section component applications.