Effect of laser incidence angle on the femtosecond laser ablation characteristics of silicon carbide ceramics

•The ablation threshold of silicon carbide ceramics at different incidence angles was calculated.•The energy density distribution function for the tilted incident laser was derived and established.•The surface morphologies and element distributions of silicon carbide ceramics under different incident angles and powers were systematically discussed and analyzed. Due to their excellent physical and chemical properties, silicon carbide ceramics have become representative high-performance materials in aerospace, energy power, biomedical, and other fields. However, as a typical hard and brittle material, silicon carbide ceramics possess incredibly high hardness and brittleness, which pose challenges to traditional mechanical processing methods. Laser processing, as a non-contact method, offers a wide processing range and high processing efficiency and has broad application prospects in the field of hard and brittle material processing. In this paper, laser ablations of silicon carbide ceramics with various combinations of process parameters were carried out by using a five-axis infrared femtosecond laser processing system. The changes in the ablation morphology with different incidence angles and laser power were discussed. The results demonstrate that the ablation threshold of silicon carbide ceramics initially increases, then decreases, and finally increases with the increase of laser incident angle. This trend may be attributed to the effect of the incidence angle on the laser absorption rate of silicon carbide ceramics. The ablation morphology of silicon carbide ceramics can be divided into three zones based on color and oxygen distribution: the ablation removal zone, ablation edge zone, and ablation affected zone. At the same laser incidence angle, the ablation range and depth gradually increase with the increase in laser power, but the growth rate gradually decreases. Furthermore, at the same laser power, as the incident angle increases, the laser energy density gradually decreases, and the long axis of the actual ablation area gradually lengthens while the short axis gradually shortens. This work could provides technical and theoretical support for laser surface processing at multiple incidence angles, which is conducive to multi-axis processing of complex curved parts.