Study on the interaction mechanism between laser and rock during perforation

In this paper, we describe the experimental laser perforation of rock. The different depth of laser penetration in the experiment demonstrated that the most important variables affecting perforation were laser power and irradiation time. The interaction mechanism between laser and rock during perforation was investigated. This investigation was conducted using an optical microscope, high-speed video images, X-ray diffractometer and other methodologies. The results indicated that the vapor/plasma of laser perforation was in a mutative process, displaying that complicated physical and chemical reactions were proceeding. A change in the molten pool during laser perforation was dynamic over time, involving heat transfer, heat radiation and instantaneous phase transition. Overheated energy in the molten pool led to material spatter which spilled from the perforation, a result of the recoil pressure of atomic vapor. XRD results revealed that the phases of rock after perforation mainly consisted of SiO2 and Fe2O3. During laser perforation, by employing either a continuous zooming process with a side blow or increasing the number of laser perforation passes with a side blow can significantly increase the depth of laser perforation.