Study on Microstructure and Properties of the Coating Layer on Titanium by Laser Gas Nitriding

The process of laser gas nitriding on the surface of commercial pure titanium TA2 was carried out and the compact coating layer without crack defects was obtained by 5 kW continuous wave CO₂ laser under N₂ environment.The microstructure of nitriding coating layer was analyzed by scanning electron mi-croscopy (SEM) and energy dispersive spectrometer (EDS),and the microhardness of the nitriding layer was measured by microhardness meter.The results show that TiN is formed on the surface of TA2 which serves as a reinforcing phase by laser gas nitriding.The nitriding layer mainly consists of TiN with fine and dendritic structures.The surface color and feature of the TiN coating layer change with the increase of laser power.The microhardness and properties of TA2 are improved obviously.