Analysis of fracture surface for sapphire cut by long pulse laser

Fracture surface of sapphire cut by long pulse laser under different shroud gas was investigated. (0001) plane of sapphire was cut by long pulse Nd:YAG laser with same parameters under N₂, Ar, O₂ shroud gas. The phase and morphology of fracture surface were characterized by XRD and SEM, respectively. The results showed that cutting depth of sapphire under Ar gas is the largest, and fracture surface for sapphire is much flat with metallic-colored, and the dominant phase is polycrystaline α-Al₂O₃ with a small quantity of metallic Al phase; fracture surface under N₂ gas is powdered without metallic-colored, and the dominant phase is polycrystaline α-Al₂O₃ with a small quantity of AlN phase; cutting depth of sapphire under O₂ gas is smallest, and powdered seriously with polycrystalline α-Al₂O₃, the directions of three kinds of cutting stripes are all reverse to laser cutting direction.