Laser nitriding of titanium surfaces for biomedical applications

In this paper, titanium nitrides were produced on commercially pure titanium samples by laser nitriding processes, with the goal of improving bio-compatibility and corrosion resistance. To identify the critical set of laser nitriding processing parameters (a combination of both laser scanning parameters and the N-2 content processing gas), mouse MLO-Y4 cells were utilized for bio-compatibility evaluation, and simulated body fluid was used for electrochemical behavior examination to characterize corrosion performance. The modified surfaces were also characterized with scanning electron microscope, X-ray diffraction, and nano-indentation techniques to reveal the connections between the bio-compatibility/corrosion resistance performance and the nitrided layer composition, thickness, and surface roughness. For improved bio-compatibility and corrosion resistance performance, a dense and thick titanium-nitride dendritic layer is desirable, which can be formed in a pure N-2 environment, together with a high laser energy density.