Analysis of laser gas nitrided titanium by X-ray photoelectron spectroscopy

Nitriding is an effective method to improve the surface properties of titanium for many demanding applications such as surgical implants. In this study, a continuous wave Nd-YAG laser was used to conduct laser gas nitriding (LGN) on the substrate of commercial pure titanium. The surface characteristics of the titanium before and after the LGN process were analyzed by X-ray photoelectron spectroscopy. The results showed that most contamination signals were eliminated by sputtering the tested sample for 1 min. The nitrided surface layer created by LGN on titanium was found to be comprised of TiN, TiNxOy, TiO2, and TiC. TiO2 was found only existed at the outmost surface layer and the TiN concentration in the nitrided layer increased with increasing depth. Titanium carbide was not detected on the surface of the mechanical polished Ti, but on the laser gas nitrided sample.