Kinetics of titanium nitriding under CW CO2 laser radiation

Solid-phase nitriding of titanium by a CO2 laser was carried out in order to investigate the growth of nitrided layers under CO2 laser irradiation. The results show that the nitriding kinetics obey parabolic laws, and are therefore controlled by species diffusion. Direct irradiation of the substrate with CO2 photons does not produce any specific assisted nitride growth. From the evolution of the thickness of the nitrided layers with time, the nitrogen diffusion coefficients are estimated. The nitrogen concentration depth profiles calculated using Fick's equation are compared to experimental nitrogen depth profiles. (C) 1997 Elsevier Science S.A.