Surface nitridation of titanium by pulsed Nd:YAG laser irradiation

Surface nitridation of titanium is an adequate method to improve the hardness and wear resistance of the material. We report experimental results concerning the surface treatment of titanium by pulsed Nd:YAG (λ=1.064 μm) laser irradiation in nitrogen atmosphere. Titanium foils were scanned with constant velocity by high repetition rate (1 kHz) laser beam pulses, and the most appropriate irradiation conditions were determined to obtain titanium nitride surface layers without defects or corrugations. The best results were obtained at laser intensities just under the transition from surface melting to ablation. The obtained layers were characterised by surface profilometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and spectrophotometry. In the XRD spectra of the films the positions of the (h k l) reflections reproduce the standard data of the tetragonal δ′-Ti2N phase. In the literature films containing tetragonal Ti2N phases are described as having better mechanical properties, corrosion and wear resistance in comparison with cubic TiN.