As a typical ceramic matrix composite (CMC)

carbon fiber-reinforced silicon carbide matrix composites (C/SiC) exhibit outstanding properties

including high specific strength

high specific stiffness

and high-temperature resistance

making them widely applicable in aviation

aerospace

automotive

and other advanced engineering fields. To investigate the surface damage forms of C/SiC composites under different energy fields

this study conducted conventional scratching (CS)

laser-assisted scratching (LAS)

and laser-ultrasonic hybrid scratching (L-UHS) on three typical fiber orientations. The scratching forces and surface morphologies under these three scratching methods were systematically compared to analyze the influence of laser-ultrasonic hybrid energy fields on surface damage of the material. The results show that

compared with CS and LAS

L-UHS can effectively reduce scratching forces and improve machinability. L-UHS demonstrates distinct fracture mode transitions across different fiber orientations: In the parallel orientation

fiber bending fracture is significantly reduced

and the primary failure mode is interlaminar fracture; In the inclined and perpendicular orientations

the fiber failure mode transitions from bending fracture to shear fracture. This study provides theoretical guidance for laser-ultrasonic hybrid machining of C/SiC composites.