(1. College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306, China) (2. Shanghai Engineering Research Center of Marine Renewable Energy, Shanghai 201306, China)
Surface graphitization behavior of diamond reduces the machining difficulty of diamond materials, thus, research on the factors that induce graphitization of diamond is expected to provide new clues for the technological innovation and development of diamond processing methods. The induction mechanism of laser parameters and stress on diamond graphitization is summarized. Laser induced graphitization mainly refers to the heating induction of short pulse laser during diamond processing, that is, the short pulse laser leads to a sharp raise of temperature, breaks the carbon-carbon bonds of diamond and reconnects them to form graphite structure. In addition, laser energy density, pulse width, number of pulses, laser power and laser pulse repetition frequency are related to each other during laser processing, which together affect the process of diamond graphitization.Stress induction mainly refers to polishing or indentation process, by increasing the pressure to change the bond length and bond angle of the diamond structure to make the diamond structure unstable, and the subsequent decompression process makes its compressed unstable diamond phase change to a stable graphite phase. Moreover, transitional metals such as iron, chromium, cobalt, nickel, platinum, and titanium have catalytic effects on the graphitization phase transition of diamond, which are mainly manifested as: the unpaired electrons in the metal valence layer structure pair with the electrons on the diamond surface to form a chemical bond to further reconstruct the graphite structure. Based on the diamond graphitization induction mechanism, it is proposed how to improve the processing efficiency in the processing of diamond materials and improve the surface properties of diamond materials according to the characteristics of graphitization.