Micro-Arc Nitriding of Titanium Surface
When a surface of a titanium disk was melted in an atmosphere of pure nitrogen using a 3D Micro Welder which was designed by the present authors, the surface was nitrided to a depth of 90 to 260μm depending on the arc current of 6 to 24 A. The concentration of nitrogen in the nitrided layer was approximately 50 mol% at the surface, and the concentration decreased as the distance from the surface increased. A TiN layer was formed at the surface, and beneath the TiN layer, a dual phase layer of TiN and α-Ti was formed. Vickers hardness was approximately 1800 in the TiN layer and it varied from 900 to 200 in the dual phase layer as the distance from the surface increased.
Omer Van der Biest, Michael Gasik, Jozef Vleugels
K. Matsuura et al., "Micro-Arc Nitriding of Titanium Surface", Materials Science Forum, Vols. 492-493, pp. 225-228, 2005